worldradiohistory.com...Head-end through drop materials, it performs the way we say, or we'll correct it — immediately. Satisfaction guaranteed. - • Head-end Moll** ,* In • •

** ,x*,x4.4**********-.. 530 COU74294

. FR ED MCCURMACK DES ENG S TAU E:NG

BOX 5221 ST UNIV FARGO ND

Head-end through drop materials, it performs the way we say, or we'll correct it — immediately.

Satisfaction guaranteed.

Head-end - • -

Moll** ,*

In • • • -

i ment we sell.

All items carry the manufacturer's full warranty.

We'll also compete with any distributor on price, selection, delivery, and service.

We stock all major brands, and can tailor packages to your needs.

Cable Services Company Inc.

Items arrive when you need them, not sooner or later.

And our engineers and technicians can answer any questions you have about design, installation, or field performance.

Call Cable Services with your next order, or for a free catalog: 1-800-233-8452. (In PA, call 1-800-332-8545)

2113 Marydale Avenue, Williamsport, PA 17701 Reader Service Number 2.

ALL GUTS= SUPERIOR ATTENUATION

Center conductor totally bonded to polyethylene.

100% bonded construction increases mechanical strength and minimizes

possibility of suck-out.

Polyethylene enclosed air "THE PERFECT" dielectric

- 93% velocity of propagation.

Medium density jacketing.

Aluminum sheath totally bonded to polyethylene structure.

NO FOAM TO DAMPEN YOUR SIGNAL

Anyway you slice it, manufacturers of foamed cables have been scrambling to attain the superior attenuation characteris-tics of MC? The attempt means increasing our familiar MC' diameter of .500" to .565" or .625 "; and our .750" must become .840" or .860" or .875" You may still use MC' in one size smaller

than the old foamed diameters. Even more MC' per duct, and easier handling. In aerial

installations, the effects of wind and ice-loading are reduced even further. And with the superior attenuation of MC

you don't have to clutter your lines with as many amplifiers - about 20% fewer than with foamed cables.

Low-loss MC' is your gain in many ways.

TRILOGY LEADS IN TECHNOLOGY

See

Call or write for a free sample and brochure:

TRILOGY COMMUNICATIONS INC., 2910 Highway 80 East, Pearl, Mississippi 39208

Reader Service Number 3.

us at the NCTA Show at the CATV Fremont, Booth 1309.

COMMUNICATIONS INC.

800-874-5649 601-932-4461

CONTENTS IIHIIIIIIIfflhIIHhIIHIHIHIIIIIIfflhIIIIIIIHlHIIIHIHHfflHHHHHHH

Departments

Publisher's Letter 6

News 10 Cable '87: The National Show agenda, WIC endorses BCT/E program, and more.

Blonder's View 16 The first in a series on patents and other intellectual property.

Product News 106

The O.K. Bull Corral 106

System Economy 108 Practical considerations for upgrading a cable system are discussed.

Preventive Maintenance 110

Building a system history now can help offset problems later

Construction Techniques 114 The advantages of recycling coaxial cable are examined.

Keeping Track 116

Tech Book Applying Ohm's law formulas to CAN situations is explained.

117

Calendar 120

Ad Index 121

Ciciora's Forum 122 In the battle for signal quality, there is competition.

SCTE Interval 57 This month's issue contains the updated national bylaws.

Cover "Interfacing" by Geri Save; Convention Center courtesy Las Vegas News Bureau.

Fiber-optic links 94

TEs7 Loc•rioN No

AND

Tech Book 117

Preventive Maintenance

TEST ROINT

LINE EXTENDER$ LOCATED AT

110

Features

The electronics interface mess 18 Walt Ciciora of ATC outlines the hype, hysteria and hope in creating an interface standard.

Consumer friendliness Approaches in interfacing VCRs and other electronics are illustrated by Jerrold's Dave Wachob.

26

Interfacing with the VCR 42

Zenith's Michael Long details interface alternatives.

Implementing BTSC stereo 52 Steve Fox of Wegener provides considerations for stereo in thelleadend.

Stereo signals over microwave 76 Adding stereo on FM links is described by Luis Rovira of Scientific-Atlanta.

A multifaceted problem: Leakage 78 Were CATV leakage problems different 10 years ago? A view from Robert Dickinson.

Accumulating leakage data 92 Jones Intercable's Bruce Catter reveals the latest results and observations of ground-based testing for CLI.

Transmission via fiber optics 94 Applications in sending multiple video signals over fiber-optic links are explained by Jack Koscinski of General Optronics.

1987 by Commurkcakons Technology Pubhcations Corp All nghts reserved Communecahons Technology"' (ISSN 0884.2272) IS published monthly by Communications Technology PubIcafions Corp , 12200 E Briarwood Ave Sude 250. Englewood. Colo 80112 -- or — P 0 Box 3208. Englewood. Coto 80155. (303)792-0023 May 1987. Volume 4. Number 3 Office ot publication is 12200 E Brerwood Aye . Suite 250. Englewood. Colo 80112 Change of address nofices should be sent promptly, provide old (or coped) malIng label as well as new address. Inducing ZIP code. allow 6108 weeks for change Second-class postage pad at Englewood and Denver. Colo POSTMASTER Please send address changes to Communicatens Technology, Box 3208, Englewood. Colo 80155

4 MAY 1987 COMMUNICATIONS TECHNOLOGY

THE WORLD'S FIRST 550 MHz, FREQUENCY AGILE, MODULATOR IS READY

Finally . . . a full-featured, high performance modulator that simplifies headend opera-tion. Jerrold's COMMANDER 5 modulator does so many things so well, it will change the way you think about your headend.

With frequency agility up to 550 MHz, COMMANDER 5 can provide any channel in your headend. That flexibility means peace of mind because it reduces your channel down-time and your investment in spares. Since it also simplifies Jerrold's inventory, rapid

delivery. .. usually within 15 days. .. is a simple matter.

High quality and reliability come standard with COM-MANDER 5. Jerrold uses state-of-the-art design and manufacturing techniques to reduce the number of inter-connections in COMMANDER 5 by 88 percent over its prede-cessor while offering such other features as .. .

• Front Panel Metering

• IF Automatic Gain Control

• Auxiliary IF Switching

• RF and Baseband Scram-bling Compatibility

• BTSC Stereo Compatibility

• FCC Compliance . . . and More!

COMMANDER 5 provides everything you want in a mod-ulator; it reduces your channel downtime, simplifies ordering and is ready now.

For more information, contact your Jerrold Account Execu-tive or call or write Jerrold Division, General Instrument Corporation, 2200 Byberry Road, Hatboro, PA 19040. (215) 674-4800.

JERROLD . . . where innovation is a tradition.

See us at the NCTA Show. Booth 2100.


GENERAL INSTRUMENT

General Instrument 1987

Beast 11 A artment Box

Cable

Affordable Security

Security Systems, Inc. Reader Service Number 5.

PO. Box 2066 Auburn, Alabama 36830 205 821-0745

See us at the NCTA - Booth 1740

PUBLISHER'S LETTER 111111111111111

Serving your country I'm no gambler, but I'm putting my money on

a terrific NCTA Show May 17-20 at the Conven-tion Center in Las Vegas, Nev. This year's theme is "Cable television serving America," which sums up what this industry is all about. This is the show everyone goes to (or would like to), not just because it's the biggest, but it's where everything comes together. New technologies are demonstrated on the exhibit floor and discussed in seminars, FCC policy issues are debated in question-and-answer sessions, and a myriad of other topics for all facets of the in-dustry are offered. A complete listing of technical seminars and

other events appears in the "News," beginning on page 10. We'll be there in force, as usual, with our CT Daily, bringing you up to date on the various technical sessions and exhibit floor ac-tion. If your company has something of interest to include in the daily, just stop one of our staff at the show.

It won't be all work and no play. Baby boomers (like me) can enjoy the Welcome Party in the rotunda Sunday, May 17, with entertainment pro-vided by Papa Doo Run Run. Also, the System Awards for Cable Excellence (ACE) will be presented Monday evening at the Hilton. And the gala dinner dance and national awards ceremony will occur Wednesday evening. (But if you're still looking for fun, think "Vegas.")

Overwhelming success Last month's SCTE Cable-Tec Expo was an

overwhelming success. Everything—from the technical sessions to the exhibits to the Expo Evening at Medieval Times—contributed to the excitement and feeling of sensory overload. Con-gratulations to Bill Riker, the SCTE staff and the Florida Chapter for putting together the best ex-po to date. The expo is another indication that the SCTE

has been right on target in its direction to pro-vide educational experiences for the industry's engineering community. As the Society's official trade journal, CTis proud to be a part of that direc-tion. We'll be providing the expo wrapup in our June issue. The SCTE's BCT/E Certification Program

picked up yet another endorsement last month, from Women In Cable (WIC). On April 1, the WIC national board unanimously voted to endorse the program and stated that it provides valuable pro-fessional development for cable technicians and engineers. Meanwhile, the SCTE board of direc-tors gave high praise and an endorsement to WIC's Certificate in Cable Management Pro-gram. Three individuals behind the scenes dur-ing this chain of events should take a bow: SCTE's Ron Hranac, WIC's Priscilla Walker and CTs Rikki Lee. Congratulations also go out to the SCTE's

Technical Scholarship Program winners Charles Hutchens of Freedom Cablevision in Sanford, NO., and David Soldan of Lincoln Cablevision

in Lincoln, Neb. Both will receive tuition assistance for a technical correspondence course of their choice selected from the National Cable Television Institute (NCTI).

In this month's Interval are the official bylaws of the SCTE, including changes proposed by the national board of directors. SCTE members, please read them carefully and send in your ballot. Mark your calendars: Next month isthe North-

east Cable Television Technical Seminar, to be held at the Roaring Brook Ranch Resort in Lake George, N.Y., June 15-17. The event is co-sponsored by the SCTE and the New York State Cable Television Commission. Topics will include improving customer satisfaction, Ku-band technology and 550 MHz systems. For more in-formation, contact Robert Levy at (518)474-4992.

I'd personally like to welcome Jim Farmer to our advisory board. Jim is a product develop-ment engineer with Scientific-Atlanta and has been in product design at S-A for 18 years.

Finally, we've been busy lately gearing up for our new publication. That's right: We've acquired CATJ, the standard for the small independent operator, and Cable Tech, NCTI's journal. The two will be combined into one monthly magazine, with its focus directed at the cable technician and installer. Beyond that, folks, our lips are sealed. Except: LOOK FOR IT!

6 MAY 1 9Ei7 COMMUNICATIONS TECHNOLOGY

THE STEREO ENCODER SO ADVANCED, IT SOUNDS GOOD EVEN IN PRINT.

• Frequency response goes to 15 KHz: +1 - 0.5 dB, 50Hz to 14 KHz: - 3 dB at 15 KHz.

Compact single-rack unit saves space.

tee

• Encodes discrete left and right channel baseband inputs into BTSC format.

Front-panel access to all audio input level controls.

Optional dual subcarrier demod-ulator and SAP

tor.

You couldn't pick a better time to offer stereo TV. Because there's never been a better BTSC stereo encoder than the Scientific-Atlanta 6380. And the more you hear about it, the better it sounds.

Everything about the 6380 was designed to make your life easier. For example, a built-in cal-ibration test tone allows you to adjust for maximum stereo sepa-ration without a lot of expensive test equipment.

All major controls and indica-tors are located on the front

,o ,ce

,fre e

e

Optional internal 4.5 MHz modulator.

Front-panel LED bar graphs for left, right and SAP input levels.

dek. complete operat-

'. ing temperature

Built-in calibra-tion test tone.

LED indicators for SAP carrier, override, video lock and over-modulation status.

panel for easy monitoring. And every unit is factory tuned and tested to ensure precise, consis-tent performance.

But don't let all these features fool you. The 6380 only sounds expensive. It's actually an econom-ical way of enhancing your service without adding channels. And in the bargain, you get the same Scientific-Atlanta quality that goes into the rest of our full line of headend equipment.

If you think our 6380 stereo encoder sounds good in this ad,

• Typical stereo separation is better than 34 dB from 50 Hz to 14 KHz, and always better than 26 dB over the

you haven't heard anything yet. Call us for more information at 1-800-722-2009 or write to Scientific-Atlanta, PO. Box 105027, Dept. AR, Atlanta, GA 30348.

Scientific Atlanta

See us at the NCTA Show, Booth 2142. Reader Service Number 6.

Analysts Service Specialists

CONVERTERS Expanded Repair Service includes Oak addressables and Jerrold addressables.

Manufacturers' Authorization

4Eppou, img

Including all factory authorized modifications.

Servicing single channel and multichannel,. unscrambled and addressable units by many manufacturers.

LINE EQUIPMENT • HEADEND GEAR • TEST EQUIPMENT Servicing most manufacturers - Emergency service available

SATELLITE EQUIPMENT Receivers, LNAs and block downconverters

PROOF-OF-PERFORMANCE Vans equipped with computerized test equipment

COMPUTER AIDED TESTING SYSTEM

Monitors your system operation (frequency, levels and trends) local or remote

Fully computerized - including reports

Innovation in Services and Products for Cable

Analysts k)

Corporate Office: 112 E Ellen Street

Fenton. MI 48430

(3131 750-9341

Eastern Facility: A.e

W Columbia. SC 29169

'04.3910


Western Facility: 2245 Camino Vida Roble

Carlsbad. CA 92008

(619) 438-4405

RF /Superior: 2010 Pine Terrace

Sarasota FL 33581

(813) 9221551

COMMUNICATIONS TECHNOLOGY

Paul R. Levine 'resident/Publisher .

Geneva Hobza `-ssistant to the Publisher

Rob Stuehrk '..11,onal Sales Manager

Jim Dickson • ,eutive

Steve Shriver • , utive

Greg Packer arketIng

Mary L Sharkey

Toni I. Barnett VP ol Edarir

Wayne H. Lesley Mar- vpng Editor

Rikki T. Lee ee Editor

Lawrence W. Lockwood East Coast Correspondent

Marla Sullivan Production Coordinator

Sharon F. Lesley Art Director

Brad Hamilton Artist

Office: L;OfnrrIUnealons Technology PublicationsCorp 12200 ir .vooci Ave Slide 250. Englewood Colo 80112. (303) • Mailing Address: P 0 Box 3208 Englewood. Colo

Advisory Board Austin Cory& l .‘rrierican T, and Communications Corp

Richard Covell ';eneral Instrument/Jerrold Division

Len Ecker .aant to CATV Industry

James Farmer àcentric Atlanta Inc

James M. Golden listed Cable Television Corp

Ron Hranac .ones Intercable

Robert Luff

Clifford H. Paul • r ,pneer to RTK Corp

Dan Pike

William Riker u'y of Cable Television Engineers

Clifford Schrock .r:onsultant to CATV Industry

A.H. Sonnenscheln -1ughesA,rcratt Co /Microwave Communrcations Products

Raleigh B. Stella Ill American Television and Communications Corp

David L. Willis

SCTE Board of Directors At-Large Directors

Richard Covell General i` •• • 'art/Jerrold DIVISIOU

Len Ecker Consultant

John Kurpinski Consultant

Robert Lull Jones lntercable

David L. Willis Tele Communications Inc

Regional Directors

Robert Vogel Rego,' 1 Director Ha: , • : Cablevision

Ron Hranac Ri': Director Jo` , •"'cable Inc

Bill Kohrt Re,; Director Ge ,, -• ,-strumenl/CommScope

Gerald Mamell Perpon 4 Director • pas Cornmuricallons Corp

Michael Aloha 5 Director

.virme/The Movie Channel

Gary Selwitz Region 6 Director Warner Amer Cable Communications

WA. Devereaux Region 7 Director American Cablesystems

TBPA

SCTE

See us at the NCTA Show . Booth 3542.

EFFICIENCY EXPERT New SUPER SENTRY Standby Power is 92% Efficient

If an inefficient power supply has been robbing you of profits, it's time to call in the efficiency experts, LECTRO. The new SUPER SENTRY standby power supply operates at 92% efficiency in normal full load mode. And that can mean significant savings on your electric bill. As

much as 10°. over other power supplies. The SUPER SENTRY is the newest innovation in Lectro's Super Line. To get all the facts about the Super Sentry, the Super Ferro, and the Super

Brute, call 1-800-551-3790. Ask for the efficiency expert.

RO A Burnup Sims Cable ducts Group Company

Le ctro BURNUP SIAM CABLE PAODUC TS GROUP

SUPER SENTRY




Free Catalog of CATV/Telcom Equipment and Hard-to-Find Tools Jensen's new catalog is your source for hard-to-find precision tools and test equipment used by electronic, telecommunication, and cable TV technicians, computer service bureaus, and government agencies. This popular catalog also contains Jensen's world-famous line of more than 40 tool kits. Call or write for your free copy today.

JENSEN TOOLS INC.

1

Dept. CT 7815 S. 46th St. Phoenix, Arizona, 85044-5339 (602) 968-6231

GROUNDHOG'S FINEST...

TRENCHER PROFESSIONALLY DESIGNED

WITH THE USER IN MIND Z ID- 1 ar

Portable Trencher with Automatic Clutch quickly digs 3-112" trench to depth of

12". Professional type Model T-4 is powerful,

e - . lightweight and •L equippped with

pneumatic flotation mr Pe 74

. 1., . tires, and 5 HP engine.

\, •

• 3. " .,..,.,, •,--

lb

. ...t..

. •4 . -1 1•-'''''''7,• .•

Designed for sprinkler installation it is also suited for underground cables and gas lines. It is built with the professional in mind, but because of its simplicity of controls, ease of operation and compact size it is well suited to the homeowner as well. The Ground Hog Trencher features oversize pneumatic tires, heavy duty steel fabrication, ball and timken bearings through-out, easily replaced hardfaced blades and a screw conveyor to deposit cuttings at the side of the trench.

Carbide Tipped Blades Also Available

0 GROUND NOG um. e For further information write or call. . .

25010 E. 5th Street, RO. Box 290, San Bernardino, CA 92410

(714) 888-2818 or 14800) 922-4680

See us at the NCTA Show, Booth 1108.

/

optic links' '; Mircho Davidov (Cateo, "Fiber-optic broadband systems—Present and future"; Her-mann Gysel (Synchronous), "Properties and systems calculations of optical supertrunks for multichannel TV transmission using analog in-tensity modulation, single-mode fibers and high-deviation FM"; and R. Scott Stevens (Siecor), "Fiber-optic cable in CATV applications."

• Cable television distribution—Performance and cost solutions

Moderator: Ed Milner (Arlington Cable Part-ners). Speakers: Patrick McDonough (United Cable), "High-frequency/high-density design criteria"; Daniel Smart (British Cable Services), ''Innovative aspects of a switched star-cabled distribution system"; Mark Adams (Scientific-Atlanta), -Field experience with feedforward amplifiers"; and Tom Osterman (Alpha Technologies), -Improving power supply efficiency."

3:30-5 p.m. • '. New-tech" signal prospects Moderator: R. Brian James (NCTA). Speakers:

William Glenn (New York Institute of Technology), "Compatible high-definition cable transmission technique"; Ben Crutchfield (NAB), "Broad-casting high-definition television"; Craig Todd (Dolby Laboratories), "A compatible in-band digital audio/data delivery system"; and Joseph Roizen (Telegen), "Improving NTSC in a cable television facility."

• Improved plant design and construction: Methods and materials

Moderator: Norman Santos (Oceanic Cablevi-sion). Speakers: Steven Biro (Biro Engineering), "Computer assisted design of CATV antenna tower/antenna arrays"; Randall Crenshaw (General Instrument-Comm/Scope Division), "The development of a new super-tough cable jacket"; Jack Gieck (Arnco), "Percol: A polyurethane system to simplify laying of buried cable"; and Thomas Straus (Hughes Aircraft), "Advances in AML transmitter and receiver technology."

Tuesday, May 19 10-11:30 a.m. • Security considerations: Locking the door to the candy store

Moderator: Ted Hartson (Post-Newsweek Cable). Speakers: Anthony Wechselberger (Oak Communications Inc.), -Encryption-based security systems—What makes them different and how well are they working?"; Michael Long (Zenith), "An enhanced RF television scrambling system using phase modulation"; Vito Brugliera (Zenith), "Security considerations for impulse pay-per-view"; and Mark Medress(VideoCipher Division of General Instrument), "VideoCipher II satellite scrambling system."

• Stereo television and cable—One year later Moderator: Karl Poirier (Triple Crown Elec-

tronics). Speakers: Kenneth Leffingwell (Wegener Communications), "Mutual effects of BTSC stereo and RF sync-suppression scram-bling": Bill Arnold (Warner Cable), "BTSC stereo—Implementation on normal and scram-


s't

1019»;¡;;jetee -'-

We're all under a Lot of Pressure! YOU'RE UNDER A LOT OF PRESSURE. Operating a cable TV system places you under a lot of pressure... the pressure to perform and to grow profitably. Especially since a minor equipment failure can cause a signal outage for many subscribers who remember only your mistakes.

WE'RE UNDER A LOT OF PRESSURE TOO. We have to perform under pressure too, in order to make sure that our products will perform for you year in and year out. So we design for performance and endurance, use heavy-duty parts, manufacture with care, and test our equipment every step of the way. This means that nobody makes longer-lasting equipment than Magnavox!

SERVICE WHEN YOU NEED IT. When you purchase equipment from Magnavox, you also receive the best warranty and repair service available... from Magnavox Factory Service. And when you need field service, troubleshooting, and technician training, our Field Engineering Team and Mobile Training Center will be there to help you.

A TRADITION OF RESEARCH & DEVELOPMENT. As a subsidiary of North American Philips, we carry its strong tradition of R&D into cable TV systems, with PowerdoublingTM, Feedforward, and DSS Status Monitoring Systems. And our advanced modular design gives existing systems the cost-effective flexibility to upgrade and add features.

WE HELP RELIEVE THE PRESSURE. An unhappy subscriber never forgets. So don't lose profits and customers to unnecessary service calls. Install Magnavox equipment. Your system will operate smoothly and profitably, year after year!

A NORTH AMERICAN PHILIPS COMPANY 100 FAIRGROUNDS DR MANLIUS, N Y 13104

FOR MORE INFORMATION CALL: (800) 448-5171 In N.Y. State (800) 522-7464 Telex 937-329 Fax (315) 682-9006



bled channels": James Holzgrafe (Oak), "MIS compatibility in encrypted baseband scrambling systems"; Joe Vittorio (General Instrument/Jer-rold), "BTSC performance measurement in the lab and field"; and David Sedacca (Scientific-Atlanta), "Practical considerations for BTSC stereo in the CATV plant."

12:30-2 p.m. • Implementing pay-per-view Moderator: Nick Hamilton-Piercy (Rogers

Cablesystems). Speakers: Larry Lehman (Cen-corn Cable Associates Inc.), "Technical con-siderations when implementing pay-per-view": Andrew Ferraro (Request Television), "Satellite delivered tag change system"; David Woodcock (Centel Cable Television Co. of Michigan), "Launching an ANI passing impulse PPV

system"; and Nancy Kowalski (General Instru-ment/Jerrold), "Using impulse technology to im-plement home shopping."

• Mid-term report card on consumer electronics interface

Moderator: Walter Ciciora (ATC). Speakers: Richard Merrell (Zenith), "Multi-control remote transmitter"; James Farmer (Scientific-Atlanta), "A new option in subscriber control"; Wajahat Husain (Scientific-Atlanta), " EIA IS-15 interface compatibility with RF sync-suppressed scram-bling"; and Christopher Lewis (Scientific-Atlanta), "Report on the coaxial portion of the EIA homebus standard effort."

3:30-5 p.m. • Interactive paths and progress

117MRCEPT

Traps Mean Rock Solid Security

With Intercept traps your pay TV penetration is not going to fizzle away, thanks to steady per-formance year after year.

.1111011ffl

Our traps are skillfully engineered, efficient ly manufactured, and tuned with pride in our craftsmanship, 100% quality check for lo. adj sound, hi video and pay video rejection.

Other state of the art products are: Encoders, decoders, band reject filters, multi channels traps, 100 db RFI passive, A/B switches, block converters etc. For further information or catalog write or call.

117TERCEPT

INTERCEPT COMMUNICATION PRODUCTS, INC 85 Fifth Avenue, Building 16

Paterson, New Jersey 07524


201 -279-2544 800-526-0623

Moderator: Graham Stubbs (Linear Corp.). Speakers: Dominick Stasi (Telaction), "Selective electronic home shopping"; Robert Bridge (Alpha Technologies), "A remote status monitor-ing system for one-way cable plant"; Anthony Aukstikalnis (General Instrument/Jerrold), "The interactive evolution"; and Richard Citta (Zenith), "Performance history in two-way cable plants utilizing a PSK communication system."

• Satellite delivery systems Moderator: Norman Weinhouse (Norman

Weinhouse Associates). Speakers: Paul Heim-bach (HBO), "Ku-band distribution of television programming for the cable industry"; Andrew Setos, "Cable TV satellite distribution: C- or Ku-Band?"; James McKinney, "FCC's overview on U.S. and international satellite issues."

BCT/E Program endorsed by WIC CHICAGO—At its April 1 meeting in Washington, D.C., Women In Cable's (WIC) national board unanimously voted to endorse the Broadband Cable Technician/Engineer Certification Pro-gram, developed by the Society of Cable Televi-sion Engineers. The program was designed to raise the professional status of technicians and engineers by providing standards of com-petence in broadband communications engineering.

In a prepared statement, WIC said the BCT/E program "provides valuable professional development for (technicians and engi-neers) . . . in the cable industry. We welcome the opportunity of working with another cable pro-fessional society to attain our mutual goal of pro-viding quality educational programs and oppor-tunities for the industry." On the same day, the SCIE national board

voted to endorse WIC's Certificate in Cable Management Program, developed in conjunc-tion with the University of Denver Center for Management Development.

For more information on the BCT/E program, contact (215) 363-6888; for details on the Cer-tificate in Cable Management, contact (303) 871-2927.

FCC releases leakage memo WASHINGTON, D.C.—The Federal Communica-tions Commission recently issued a public notice on "the excessive levels of radio frequency (RF) energy leaking from cable television systems." According to the statement, the amount and level of leaks found during FCC inspections indicated that "many monitoring and maintenance pro-grams are either inadequate or nonexistent."

Excessive leaks that are detected are required to be documented and repaired by the cable system. Failure to provide an adequate program of regular leakage monitoring and repair may result in a "monetary forfeiture"; leakage detected during an inspection also may result in such a penalty.

Illiiillilláliiiiiiiiigillitilliiiiiellià611111ig611111111 111111111111111111111111111111111111111111111111111111111111111111111111111111111111111131111M11111111

-IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII .11111111111111111111111111111.111111111111111111r7r7-11-771-711-=Irrill11111 IMIIIIIIIIIIIIIIIIIIIIIIIIIMIIIIIIIIIIII I I I i 1 ' I "I 11 .J '9 I I Mr» 1111111111111111111111111111111111111111111111 .dl I II I 1 ill II "1 MI I I 11111111111111 MIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIILIIILALLA-1.L.1.26.-4.-111111111111 ::.11111111111111t111111111111111111111111111111111-717.I7T27:7E-J-7:7-inam Immummuummum • I "I II II 161 11 I I I 'I 11111111111 IIIIIIIMIIIIIMIIIIIIIMIIIIIIMIIII I I Ill II MI UM II I I I 1 MUM IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIL.À.à L.h.gdlLà.lb.4J6J11111111 .IIIIIIIIIIIIINIMIIIIIIII Wog 71-1FM211111111111111111111111 11111 0" i I All I $11111111111111111111111111 :U miziaLl.Lipiammummul .I , I 11 it II II I 111111111111111111111111, I% I ri _ I III 111111111M11111111111111 in lirsgtàwrqi-iuieIMIIIIIIIIIIIIIIII III 1111'4111 1.111111111111111 la A 1 1 Ill Loll J I 111111M1111 Ill 4i..- 1111111111111111•111- III I I 11 I I 1111111111111111111111- a IIIIIIIMIIIIIIIIIIIIII II , Now there's an in xP ns. 2M111111111111 111 age cletectlieni-clevtce

III Proeezl,r installer wiineHMINIIII

I elfi aaFÑlnai l ' Mevzientillin II• ed detection device ° ttem, ....mmmium a sy to use, leakage o ito

'II become secondm inglinnill a lmostimm •i• tely Eli Z112111111111111111

z the ng entry tOinst :fdffie BB llININI

MI nd cAli)1 e culY egaM1111.111111

MI arAiramme -mum fid,if a' / I/ omunie a Inomerui/M111111111 II 1111111111111111111111111111111111111111111 IllJi , MI

111111111111111111111111111111111111111 „ ,„ 111111111110e "MPH!' ' . linial

•MI 11111111111111111111111111111111111111161 MANI NE L.VE g4 44 . INC. 3. Tr BEM

• IIIMMIMIUMMEMEMI 0 C ea .2gelgal 1.1111.

IIIMMIN111111111111111111111111111111111111111.1111111.111Millnia

•1111111111111111111111111111111111111.11111111111111111111.1111111111111•111111

IIIIIIIIIIIIIIIIIIIIMIMIIII=:=E=11MMIMIIIIIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIMIIIIIIIIIIIIIMIIIIIIAM!!E!!M!!1!1111111MMIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII 111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 immumummulummumi 11111111111111111111111111•11111111111111111111111111111P

The consumer electronics interface mess By Walter S. Ciciora

ArneIrcdf kelevlbrun arid u,i.CatrOrIS CL r1

The consumer electronics interface with cable 'sa mess. How did we get into this situation? What are the options? And is there any hope?

In the past, there was a lot of finger pointing over who was to blame. The cable industry felt that consumer electronics manufacturers created the cable-ready TV just to increase prof-its without regard for subscribers' needs. They saw cable as uncoordinated and lacking stand-ards; e.g.. a product that works fine in one system is a disaster in another. There were areas where the two industries

were in genuine conflict. Some cable operators introduced remote controls as a means of generating new revenue streams. But this prac-tice interfered with the subscribers' ability to use

purchased remote controls and with the salability of high-end TV receivers. For the consumer elec-tronics industry, this was a serious matter. To manufacturers, only high-end products have ac-ceptable profit margins; a business could not sur-vive if only low-end products are purchased. The greatest burden fell on the subscriber.

Confusion, frustration and anger were common reactions. The situation appeared hopeless un-til both industries came to the realization that our subscriber and their customer were one and the same person. If we worked together, both in-dustries and the consumer could benefit. That work has a good beginning but a long way to go before the installed base of problems are resolved.

Loss of convenience The problem seems to have two fundamental

aspects. First, the subscriber often experiences a significant loss of convenience in the use of con-sumer electronics equipment when connected to cable. Second. the installation and recon-figuration of these products and cable have become very complicated. The loss of convenience is evident every time

cable is used and manifests itself primarily through the remote control. Prior to the cable in-stallation, a remote control was a handy conve-nience. But when a cable converter is installed, the subscriber has to deal with multiple remotes: one, to turn on the television and tune it to Chan-nel 3; another, to select cable channels. And back to the TV remote to adjust volume or mute the sound. The VCR in a scrambled cable environment

provides the most frustration. With a converter ahead of the VCR, the VCR timer no longer can select the channels to be recorded. Only the channel originally selected on the converter can be recorded without further intervention. A potential solution is the introduction of converters with timers or converter remote controls with built-in timers. As a practical matter, this approach in-

troduces another seres 01 steps that must be ex-ecuted flawlessly if a successful recording is to be made. Subscribers are not looking for a challenge to their mental abilities as they try to set up their equipment to record a program just before rushing out the door to an unexpected event. The complication of installation occurs only oc-

casionally. It is first noticed after the initial in-troduction of cable and then appears each time a new product is added to the home entertain-ment center or after moving the equipment for cleaning or painting. The complicated installa-tion increases the likelihood of implementation errors that deprive the subscriber of the full func-tionality of the cable service or the consumer electronics products. This further contributes to the loss of convenience of use. One of the main problems with the cable-ready

TV is that nothing in life is ever really ready. Just as things appear to be almost ready. something changes and the readiness is jeopardized. Recognizing the negative implications of cable-ready, some manufacturers have chosen the term "cable-compatible" instead. But "compati-ble" is a rubber word that often is stretched to meet the needs of the moment. In the strict sense, "compatible" means that two things—like a cable system and a cable-compatible TV—work together perfectly without loss of functionality on the part of either. Loosely, it means they both run on electricity. Unfortunately, it is used loosely more often than strictly.

Initially, being cable-ready added little cost to a television. As an inexpensive feature on a premium electronic tuner, it only required memory space in the microcomputer that con-trolled the tuner. The tuner was a big improve-ment over the old-fashioned mechanical clunker. The extra cost was for the improved tuner, not for the cable-ready feature. Later, as more and more channels were added, a small increment in cost was incurred as another set of tuning diodes was added and more memory was re-quired for the microcomputer. Note that elec-tronically controlled tuning is mandatory for prac-tical tuning of cable channels. (Can you imagine a 105-channel mechanical tuner? An automobile steering wheel would be needed to turn the dial!) There are only two requirements for a televi-

sion or VCR to be cable-compatible: First, the channels the subscriber is interested in receiv-ing must be available without the need of hav-ing another tuner ahead of the TV set. Second. the TV signals must not be directly picked up off-air by the television's internal circuits. This is called DPU for direct pickup; DPU results in ghosts in the picture. In cable systems with an HRC (har-monically related carrier) frequency plan, objec-tionable diagonal bars mar the picture. DPU is not a new phenomena. In fact it is the

reason why converters were invented in the first place. The original converters only tuned the 12

off-air channels. They were not intended to ex-tend tuning range, but only offered protection against DPU. The first requirement for compatibility can be

met in several ways. If the cable system uses traps for signal security or if the subscriber simply is not interested in the scrambled channels, a descrambler will not be needed in front of the TV set. Likewise, if a form of descrambler that plugs into the back of the TV set is used, a set-top descrambler will not be required. The second requirement is met if the

subscriber does not live near a TV transmitter, or has a well-shielded receiver. Otherwise, a con-verter/descram bler is needed ahead of the TV tuner. The remote control becomes almost useless and the subscriber is frustrated.

This definition of cable-compatible is situa-tional. If a subscriber who only had basic now upgrades to HBO in a scrambled system, the formerly cable-ready TV will lose functionality when a set-top descrambler is added. Likewise, if the subscriber moves closer to a TV transmit-ter. a TV receiver that previously worked satisfac-torily may start to exhibit ghosts. A converter may be required to eliminate this problem.

What caused this mess? Originally there was very little difficulty between

cable and consumer electronics products. Both were relatively unsophisticated from a technical perspective. There was little need for the two in-dustries to communicate with each other. Things worked well. But as the technology of the two in-dustries evolved separately, numerous options became available to the designers of both in-dustries. Without standards and vigorous com-munications between the two industries, designers in both made a variety of choices that were perfectly valid, taken one at a time. The trou-ble arose when these choices were expected to function together.

Cable's contribution to the mess includes a variety of frequency plans in different cable systems and the use of scrambling. Scrambling is a fundamental technique for restricting access to cable programming and thereby ensuring that it can be sold. It is likely that scrambling will be part of the cable tool kit for the foreseeable future. Nonetheless, it must be recognized that, more than any other factor, scrambling as done in the past contributes to the interface mess. The electronics industry's principal contribu-

tion to the problem is the failure to adequately shield the internal circuits of receivers from strong off-air signals. The retail segment of the business added to the difficulties with less than clear adver-tising. Certain other actions, such as the addi-tion of new features that coincidentally place ad-ditional demands on cable systems, are a pro-per business practice, which for the most part benefit the consumers. These actions are necessary for survival in this


Beat the traffic. M/A-COM opens up a new lane for cable

operators with our new 18 GHz microwave system.

If you've been looking for an open frequency at 6 or 12 GHz, you're not alone. In many areas, they simply aren't available: there's too much traffic and not enough spectrum. M/A-COM's new 18 GHz micro-

wave system gives you another option: a wide-open band which the FCC has assigned to cable oper-ators. It gives you 50% better link availability (or 40% longer range) than 23 GHz, and none of the con-gestion of the lower frequencies. The MA-18CC is a fully-featured

microwave system, designed to meet or exceed all RS-250B short-haul performance specifications. It is field tunable, and a single gunn

oscillator covers a wide selection of fre-quencies so spare parts can be kept to a minimum.

For over 20 years M/A-COM MAC has specialized in providing microwave radio equipment to cable operators and broad-casters. Every unit with our name on it is built

in our own factory, so we not only control the quality, but we know how to service it.

For more information on how you can streamline your microwave needs, contact M/A-COM MAC, Inc., 5 Omni Way, Chelmsford, MA 01824, (617) 272-3100.

Reader Service Number /8. See us at the NCTA Show, Booth 3019.

highly competitive business. Examples include the "picture-in-picture" (PIP) feature, which places a small second image on the screen along with the main picture. It is offered in many of the new digital televisions and VCRs. PIP re-quires two descram biers when the subscriber wants both the large and the small image to come from scrambled channels. Manufacturers will continue such innovation in the pursuit of a viable market share. Cable will have to be nimble on its feet and accommodate these technical advances.

Perhaps the most important consumer elec-tonics trend has no technical component: It is simply proliferation. As prices continue to erode, more and more televisions and VCRs will be

found in the home. If cable service is to maintain its value to subscribers, it must be available on most of the homes' receivers. Otherwise. subscribers will have the sense that, in most cases, they can do without cable. It is not prac-tical to have full converter/descramblers on top of each receiver. Acknowledging that the root of the problem

is the separate evolution of the technologies of the two industries, an important step toward a solution is to build bridges between the in-dustries' engineers. This will facilitate a con-vergence of the technologies. That is the motiva-tion behind the EIA/NCTA joint engineering com-mittee. The EIA (Electronic Industries Associa-tion) represents the manufacturers, while the Na-

plooking into the1000series_

IS LIKE LOOKING INTO

THE FUTURE! WITH THE LINDSAY 1000 SERIES TRUNK, YOU CAN START WITH AN

OPEN RETURN SYSTEM & MULTIPLEX WHEN YOUR SUBSCRIBER BASE HAS EXPANDED. BY SIMPLY ADDING MODULES. BY MULTIPLEXING, THE LINDSAY 1000 SERIES CAN ACCOMMODATE UP TO 400 CONTINUOUSLY TRANSMITTING HOME TERMINAL UNITS, PER BRIDGER STATION. THE SYSTEM ALSO FEATURES FAILSAFE FORWARD & REVERSE STATION BYPASS, POWER DOUBLING & FEED FORWARD, AS WELL AS DIAGNOSTIC CAPABILITIES.


COL. ADVANCED COMM. 303-596-4464 OH: THE HEAD END 614-766-0874 PA: TONER CABLE EQUIP 215-675-2053

SPECIALTY PRODUCTS LIMITED

50 MARY ST W LINDSAY. ONTARIO CANADA K9V 4S7 TEL 705-324-2196


tional Cable Television Association's Engineer-ing Committee represents the technical elements of cable. This joint committee was formed five years ago to provide a forum for engineers who design consumer electronics and engineers who design and operate cable systems. These technologists communicate on important technical issues and increase their understand-ing of each other's problems and constraints. A secondary purpose is to arrive at technical stand-ards for the design of consumer electronics prod-ucts and cable systems that will facilitate satisfac-tory performance.

It must be recognized that these are relatively long-term efforts. The uncoupled technical evolu-tion of the two industries has gone on for quite a number of years. Over 200 million TV sets have been placed in U.S. homes and thousands of cable systems have been built without the benefit of adequate communications. There is no escap-ing the fact that it will take time to overcome in-compatibilities built up over such a long period in such a large installed base of products and cable systems. The NCTA Engineering Committee recognizes

the importance of these long-term efforts. But it is not satisfied that they are adequate. To alleviate (eliminate is not likely) the problems in the shorter term, two subcommittees have been formed. The first, under David Large of Gill Cable, has com-piled and analyzed a set of connection diagrams to aid cable technicians and subscribers in ob-taining the best results from their collection of equipment. This set of diagrams is available froin the NCTA Science and Technology department in Washington, D.C. The second subcommittee was formed under Mat Miller of Viacom to take yet another look for potential near-term solutions. This work, which has just begun, is intended to be a creative, brainstorming effort leaving no stone unturned in the search for approaches that may be helpful.

Standards efforts There are three levels of applicable standards.

The most mature standards are in the RS series. RS means "recommended standard." Perhaps the most familiar example is the RS232 standard used with computers and data communications devices. A step along the way to "RS" is "IS," which stands for "interim standard." An IS des-ignation is issued on a trial basis for a year or two. During this period, manufacturers attempt designs in order to more fully understand the consequences of the standard's details. After the trial period, the standard is amended to include learning from the past year and voted upon by the EIA for promotion to RS status. The least mature phase in the development of a standard is the "recommended practice." It is intended to indicate a direction for manufacturers to choose where there may be many reasonable approaches.

It is important to realize that these standards are voluntary; neither the NCTA nor the EIA have enforcement powers. Adherence to the stand-ards depends on the good faith of the companies involved. The channelization standard exemplifies the

process of standards creation. Engineers from the two organizations met and educated each


CONNECTORS

BNC, TNC, F, N AND

PATCHING

ALSO — TRIAX, QUADRAX

TROMPETER ELECTRONICS, INC

186 La Baya Dr Westlake Vlg Ca 91362 81 707 2020 TW* 910.494 1210


DATA CABLE DISTRIBUTION SYSTEMS

TROMPETER ELECTRONICS manufactures the widest selection of CONNECTORS, CABLE DISTRIBUTION PANELS PATCHFIELDS & CABLE ASSEMBLIES available. Choose from over 30 families of connectors for UL approved Coax, Twinax and Triax EMI/RFI applications. Our all new T-15 catalog includes guidelines for select-ing and installing these connectors as well as an ex-tended list of various manufacturers' cable and their specifications. Send for your copy NOW.

Company

Name

Address

CitylState/Zip

Bus. Phone I

PHONE (818) 707-2020 TWX: 910-494-1210

MIS or _ Dept.

FREE CATALOG

e -11 tie 6, lifts bite

de 4ssewe exii,4

FAX (818) 706-1040 coy, CT 5/87

CALL NOW

TOLL FREE: 800-645-2300

For CATV

Component Specials

' e ad conic. Id

YOUR FULL SERVICE SUPPLIER

—f

Let's See the Temtron CATV Advantage! • Lowest Prices • All Major Manufacturers U Huge Stock in Next Day Delivery

I AM PARTICULARLY INTERESTED IN THE FOLLOWING: EJ Hybrids/RF Transistors

10 IC's: Linear, C-Mos

Ill Diodes, Transistors, Capacitors

Ell Other

EJ Circuit Breakers/Surge Protectors

0 Fuses/Fuse Holders

0 Amplifiers, Line Equipment

El Converters (Programmable and addressable)

Urgent I need quotes now! (Specify items and Quantity)

El I make purchasing decisions. Add my to your mailing list.

Name

name

POS Phone

Firm

Address

City State Zip

CT 5/87

F--ILM CI NCI WE ARE YOUR FULL SERVICE SUPPLIER

WE SERVE:

CATV - SMATV - MATV - LAN

Check the following items that you would like to know more about and send us this card.

IN A RUSH? CALL: (614) 766-0874

_ _ Triple Crown Electronics: Modulators, processors, satellrte receivers, fully racked headends, distributton arrplifiers. Lindsay: Oft-ar antennas. microwave anter nas, satellite dishes, CATV amplifiers, taps, splitters, DC's. PicoiMacom: Complete catalog of installatice materials, modulators, processors, KB switches, arrplrfiers. and more. Video Interconnect Products, Inc.: VCR hookup tuts, FCC kB switch kits. headend channel switches, character generators. Belden Cable and Wire Jerrold Electronics Scientific Atlanta

_ Corrm/Scope Trilogy Cable LAC Connectors Gibert Connectors

CT 5/87

CONNECTORS

BUSINESS REPLY MAIL FIRST CLASS PERMIT NO 21 CHATSWORTH CA

POSTAGE WILL BE PAID BY ADDRESSEE

ROM PETER ELECTRONICS 31186 LA BAYA DR

P.O. BOX 5069

WESTLAKE VILLAGE, CA 91359-9972

NO POSTAGE NECESSARY IF MAILED IN THE

UNITED STATES

BNC, TNC, F, N AND PATCHING

ALSO—TRIAX, OUADRA:

TROMPETER ELECTRONICS,

31186 La Baya D, Westlake Vig Ca 913E= (818, 707 2020 71NX 910 494 '210


111111 BUSINESS REPLY MAIL FIRST CLASS PERMIT 184 EAST ROCKAWAY, N.Y.


Ir Et„fri,„ricosind e

15 MAIN STREET EAST ROCKAWAY, NEW YORK 11518


UNITED STATES

From:

Phone #

Contact:

PLACE STAMP HERE

HEAD END COMPANY 2690 Sawbury Blvd.

Worthington, OH 43085-1821

t:13

11dd

fIS 301Abi3S lif

ld 1

:1110A

17L80-99L (

171.

9)


other on the various methods used to allocate frequencies in the cable spectrum to channel designations. A debate ensued over the pros and cons. Some questions were deferred until more experience was gathered. The interim standard was issued in May 1983. Manufacturers then evolved their product designs towards com-pliance with IS-6. In late 1986, the committee took up the issue of finalizing IS-6 into a proposal to the EIA for promotion to RS status. The principal issues remaining were the chan-

nelization of the FM band, the order for expand-ing channel capacity and the method of count-ing channel capacity. The FM issue centers on the fact that receivers generally have traps (frequency-selective filters) in the FM band to pre-vent interference with Channel 6 reception when strong FM signals exist in the reception area. This trapping practice is essential for off-air perfor-mance; therefore, cable operators must use channels in the FM band accordingly. TV receiver manufacturers likely will strive to develop switchable filters for future products. While not technically practical at present, the need has been highlighted and the consumer electronics industry is now aware. The order in which channels are added when

capacity is expanded and a fair method of in-dicating capacity to the consumer have been agreed upon. Before the channelization stand-ard, cable companies used numbers and letters to designate channels in a variety of ways. There were a number of equally logical ways of doing this and no mechanism to coordinate between those making the choices. A serious conse-quence of this situation was that it became im-possible for product manufacturers to make receivers that complied to multiple channeliza-tion methods. Now, with IS-6, cable practice and consumer electronics design can converge over time to the benefit of the subscriber. As mentioned previously, there are two re-

quirements for true cable compatibility: 1) the television or VCR must be able to be connected directly to the cable without a converter or descrambler ahead of it, and 2) the internal cir-cuits of the television or VCR must not pick up off-air signals directly. The IS-23 standard is in-tended to set technical specifications that define what is required for a product to avoid DPU prob-lems in the majority of cable installations. Addi-tionally. IS-23 deals with signal levels, connec-tor types and the allowable level of signals back fed into the cable. The standard went up for vote at the end of

1986. TV manufacturers found its direct-pickup requirement difficult to achieve. They have asked for further clarification and compelling evidence of the need for such a severe standard. The com-mittee went on hold while this issue received fur-ther investigation. The committee will resume its deliberations in the third quarter of this year.

EIA multiport Perhaps the standard that has the most poten-

tial to solve interface problems is the IS-15 decoder interface standard, which also is known as the EIA multipart. The standard is embodied as a 20-pin plug on the back of a TV receiver or VCR that accepts a set-back descrambler. It has been adopted and endorsed at the IS level by

Nee f rom

PICO MACOM

Step Up to Guaranteed Quality at Attractive Low Prices.

UP100,,,

Features • Low cost

• High gain: 70 dB

• High output: 62 dB

• SAW filtered

• Spurious outputs down 60 dB

• High adjacent channel rejection 60 dB

• Superior low noise circuitry (6 dB NF)

• Sync tip AGC for precise signal regulation

• Stereo signal compatible

• 45 MHz IF loop-thru

• Assured reliability with 100% burn-in of all processors

Model SP-60

HETERODYNE PROCESSOR

The Pico Macom SP-60 uses the latest low noise, PLL, SAW filter and AGC techniques to provide superior processor quality and performance.

Frequency Range Low, mid, high, super bands

Max. Output 62 dB

Min. Output (for 46 dB C/N) — 7 dBmv

Output Adjust Range 46 - 62 dB

Gain 70 dB

AGC Range — 10 dBmv to + 25 dBmv input

AGC Type Keyed sync tip

AGC Stability 0.5 dB

Frequency Response ± 1 dB

Noise Figure 8 dB

Selectivity 60 dB (adjacent channel)

Spurious Outputs — 60 dB (at 62 dB output)

Aural Carrier Adjust Range — 15 dB

Two Year Warranty—Guaranteed!

incg. " PICO !VIACOM, INC. A Subsidiary of Pico Products, Inc.

12500 Foothill Blvd., Lakeview Terrace, CA 91342 (800) 421-6511 / (818) 897-0028

both the EIA and the NCTA. The principal advantage of the multipart is that

it makes a truly cable-ready receiver possible in a scrambled environment. Because descram-bling is accomplished after the receiver's tuner, the consumer product can be directly connected to cable. The subscriber regains use of the remote control. In the case of a VCR, the timer again becomes useful. It can control channel selection and turn the VCR on and off. An im-portant secondary advantage is a significant reduction in cost to the cable operator. Set-back descramblers will be 40 percent to 60 percent of the cost of set-top units. It becomes practical to provide two units, one for the television and another for the VCR. For the first time, it's possi-ble to watch one scrambled channel while recording a different scrambled channel at an affordable price. A practical limitation of the EIA multipart is that

it requires the subscriber to purchase a new multiport-equipped TV receiver or VCR. This won't happen overnight. Unfortunately, televi-sions last too long; the typical life is 12 to 14 years.

New receivers are bought every seven years, with the old unit put in the basement or donated to one of the kids who grew up with it. Significant penetration will take time. However, subscribers who feel they need a solution can contribute to it by making a purchase. Even that was unavailable just a few years ago. The situation is dramatically different with

VCRs. Since they wear out, VCRs are replaced every three or four years by heavy users. The rotating heads are a critical mechanical element in an otherwise electronic system. They clog and wear, causing expensive repair bills. In many cases, the cost of repair rivals the cost of a new unit. Since the purchase of a VCR more than doubles the trouble with the consumer elec-tronics interface, it is particularly appearing to find that the EIA multipart can bring relief when taken as an option on a new VCR. The first televisions and VCRs with multipart

are expected on the market this year. Descrambler vendors have promised evaluation samples in the beginning of the third quarter of this year, with volume delivery a few months later.

COMMUNICATIONS TECHNOLOGY MAY 1987 23


They All Fold Up For Carrying & Storage

BCC-2 Cable Caddy BCC-4 Cable Caddy BWC-16 Wire Caddy BWC-66 Wire Caddy RG-6 3 ft. Jumpers BCP-100 Cable Clip 7mm 7/16 Mini-Wrench "F" Fitting

BCC-1 BwC-1xs $27.97 $33.97

M&B SALES & MFG. BOX 206 PLEASANTON, CA 94566 (415) 443-8619

Guaranteed... An Unwatchable Picture!

But more revenue for you with the Security Trap from VITE K.

Traps are the least expensive way to turn non-pay pirates into revenue producers for your system. Traps effectively eliminate video signal. The Vitek Security

Shield and strain relief are standard with the Security Trap. Both are manufactured of high impact, U.V. resistant plastic. Strain reliefs are available in seven colors for coding your traps. The security shield and strain relief combination are avail-

MAT VITEK (JuoIlly and Innotatron

able at no additional cost when you purchase high-performance Vitek Electronics traps.

Security Traps can be made to fit any channel line-up, or customized to remove the audio or video carrier. Also avail-able without Security Shield and strain relief. To get complete infor-mation on Vitek Security Traps for your system, call or write today.

VITEK Electronics, Inc. 901 South Avenue Box 111, Horseheads, NY 14845 (607) 796-2611


The NCTA Engineering Committee has formed a subcommittee to promote and stimulate the multiport among the MS0s. While there still is a lot of work to be done, progress on this impor-tant standard is heartening.

Other interface approaches If we think further about the previously men-

tioned requirements for compatibility in the con-sumer electronics interface, we realize that there are other methods of avoiding another tuner ahead of the television or VCR. These are based on providing a broadband feed into the subscriber's home. Interdiction is applied to the channels the subscriber has not chosen. All other channels are "in the clear" Two methods are cur-rently being pursued actively in the cable industry—a jamming and a trapping method.

Scientific-Atlanta and Paragon Communica-tions, an MS0 encompassing many of the former Group W systems, are developing an off-premises technology that jams the channels the subscriber does not want. In addition, the en-tire service may be turned off at the tap. It is a fully addressable technology. From an interface perspective, its virtue is that no tuners are put in front of the television or VCR. The subscribers' purchased remote controls do their intended jobs and the VCR timer is fully functional. While there are some technical hurdles, they do not seem overwhelming. The principal challenge with this approach is economic. Since the hard-ware must be installed outside the home of every subscriber, the up-front cost is a serious consideration. The trapping method is featured by Tele-

Communications Inc. in its on-premises ap-proach, which also is being developed in part-nership with S-A. Special high-tech positive traps are installed in a tamper-evident cabinet on the side of the house. The positive traps remove jam-ming carriers inserted at the headend. Addi-tionally, some channels may be negatively trapped. Initially, the approach is not ad-dressable. However. the "hooks" have been in-stalled in the design to allow future upgrading to addressability if the business needs dictate. As with the off-premises approach, the subscriber gets a broadband feed, with author-ized channels in the clear. Interfacing is served well by this approach.

In both the on- and off-premises approaches, the consumer-friendly purpose can be frustrated if the consumer electronics product is suscepti-ble to direct pickup. DPU can become a spoiler that requires a converter ahead of the television or VCR in strong signal environments.

Is there any hope? There is a great deal of hope for alleviation of

the consumer electronics interface problem in the reasonably short term and eventual solution in the long term. Greater understanding and communication between the consumer elec-tronics industry and cable will ensure that future designs are much more compatible. More atten-tion to the issues will minimize cable practices that fail to accommodate the realities of the huge installed base of televisions and VCRs.

Yes, there is hope! E_43

24 MAY 1987



deserves Watchmanell. Superior stand-by pOwer battery.

Watchman® 11 is the technological leader in stand-by battery power, de-signed especially for CATV and other stand-by power applications. Watch-man II is madeofDuratree. This smile tough material is used in GNB heavy-duty batteries which virtually eliminates breakage in the field. The bottom line is, it's the top of the. line.

Watchman II and Absolyte are regstered trademarks and Duratrex Is a trademark of

GNB Incorporated

No maintenance.

Watchman 11's Absolyte® sealed lead acid technology means no maintenance, . and no maintenance cost. Watchman IT never needs watering, there's no acid spillage or corrosive fumes to damage expensive electronics. And because Watchman II is sealed, you can use it in - any position, no matter how remote, • even freezing will not damage it. •

/ Reader Service Number 23.

•

Premium performance..

• Compatible with float service, .and unlike most stand-by batteries, Watch-• man II can be cycled over 250 times. • Give your Hi-tech equipment all the power it deserves. Watchman 11 stand-by power battery. For more information, contact Jim

Trenter, Technical Applications Man-.. àier, GNB Incorporated, P.O. Box 64140, St. Paul, MN. 55164.: (612) 681-5000.

GNB Incorporated

Retaining consumer friendliness with CATV By Dave Wachob Manager. Pr, Jerrold Subsc, • ,,,,ns Division, General Instrument Corp

Anyone who has attempted to interface cable television equipment with today's myriad of con-sumer electronics understands the frustration associated with this task. What once was a straightforward connection between a descram-bring converter and a conventional television now has become a significant challenge—even to those familiar with the technology.

With the rapid growth and acceptance of VCRs and other cable-ready devices the problems must be dealt with effectively if the cable business is to survive and grow. •

Subscriber's dilemma The subscriber who purchases a new cable-

ready, stereo-capable, consumer-friendly VCR or television is faced with the immediate problem of how best to interface the device with the cable system for optimum performance. Among the

Figure 1: Hookup with VCR in front of converter

Cable in

Converter

Any TV

Any VCR

Figure 2: Hookup with converter in front of VCR Converter

Cable in

Any VCR

Any TV

• •

• •

• •

• •

Figure 3: Expanded setup with two-way splitter and A/B switch

Cable in

Two-way splitter

TV

Any VCR

Converter


ELIIVIIMR79R Finally, a powerful tool that eliminates remote control

inconvenience. Introducing the Pioneer SmartRemote '" — one remote that

can learn eight different functions of virtually any home enter-tainment system.

So tell your subscribers to fastforward their Fisher" VCR. Change the volume on a Sony" television. And still operate all the features of Pioneer's BA-5000 addressable or BC-4000 series standard converters.

But don't be intimidated by its power: The SmartRemote -arrives individually packaged with its own instruction manual and a full bar code for accurate tracking. We'll even provide training

for your sales reps or CSRs and promotional assistance through preprinted bill stuffers*.

Teach your subscribers the art of elimination. For more infor-mation on the most affordable learning remote in the industry call Pioneer today at 1-800-421-6450.

PIONEER' PIONEER COMMUNICATIONS OF AMERICA, INC.

600 East Crescent Ave. • Upper Saddle River, NJ 07458 • (201) 327-6400

Outside New Jersey (800) 421-6450

Fisher and Sony are registered trademarks of Fisher Corp, and Sony Corporation of America, respectively . "Minimum purchase quantity required

See us at the NCIA Show. Booth 2134. Reader Service Number 24.

Figure 4: Expanded setup using two converters

Two-way splitter

Cable in --soli

Converter el

Converter #2

Any VCR

B A4 -ai

A/B Li I switch

Any TV

items to be considered at this time are personal viewing/recording preferences; the specific hardware to be configured; ease of operation; remote control capabilities; performance trade-offs; and any inherent costs associated with "making it all work together." In addition, whether the system's premium services are trapped or scrambled also has an immediate impact on how the hardware is to be configured. A wide variety of possibilities exists for connect-

ing subscriber equipment to the existing cable

system. In fact, a recent NCTA Engineering Sub-committee on Consumer Interconnection developed 27 possible configurations, without even taking into account baseband or stereo capabilities.

In the interest of time and space, four of the more common basic configurations in use today will be described and critiqued, although many of the same benefits and limitations also are ap-plicable to similar configurations. In addition, some improvements to the basic configurations

'The subscriber who purchases a new cable-ready, stereo-capable, consumer-friendly VCR or TV is faced with (an) immediate problem'

will be proposed for an "interim solution" in an effort to increase overall consumer friendliness. Finally, some longer-term solutions will be discussed.

Today's solutions In its most basic form, the addition of a VCR

to a subscriber's cable system can be ac-complished in two straightforward approaches, illustrated in Figures 1 and 2.

In Figure 1, the VCR is inserted in front of the converter, which is connected directly to the subscriber's television. This configuration allows the subscriber to independently record a clear channel while viewing a descrambled or different clear channel. This is made possible through the VCR's internal RF splitter, when the VCR is in the "TV" mode. In addition, if the VCR is cable-ready all clear channels selectable by the unit can be recorded. Otherwise, the user is limited to Chan-nels 2 to 13.

Trackmolding, Riser Guard & Accessories

PIC is architecturally more attractive for apartment & commercial post wiring.

a Sample

Kit for evaluation, prices & complete

catalog, call or write our Distributor

Representatives or

MuItilink

7M

Engineered to Make the Difference

P.O. Box 955, Elyria, Oh, 44035 Phone (216) 324-4941

N Are You Ready To

UPGRADE? or REBUILD? • Excess Inventory Sales • Complete Bill of

Materials • Large Inventory

• ORE Upgrade Modules

• High Quality Test Equipment. DIX/Hill Matrix Generator

• Guaranteed to meet or exceed factory specs

We Specialize in BUYING, REBUILDING & SELLING

CATV EQUIPMENT

cAri SERVICES

Outside California

800/227-1200

Inside California

800/223-3152

FAST DELIVERY 40 DAY UNCONDITIONAL WARRANTY. PARTS & LABOR

\,2211 Warm Springs Court, Fremont CA 945390,

Reader Service Number 25. See us at the NCTA Show. Booth 1556. Reader Service Number 26.

All Call 1-800-843-3338 To Learn How To Thoroughly Analyze And Pinpoint Any RF Video Trouble, In Any Video Distribution System, Automatically To FCC Specifications In Half The Time!

.1:rj FI <

IV 514.114. ANAL en.

'

e e

o

At last, a TV-RF Signal Analyzer designed the way you've always wanted it . . . Meet the world's first 100% automatic FCC accurate field strength analyzer. It's exclusively designed and guaranteed to help you analyze and pinpoint any RF video trouble, in any video distribution system in one-half the time. At long last you can accurately check your signal "quantity" and • 'quality"—all automatically. Here's why . . .

Meet the All New FS74 "CHANNELIZER SR. 'Tm—the TV-RF Signal Analyzer you've been dreaming of. You'll find the pesky, time-robbing, frustrating problems all other analyzers miss with these exclusive features:

Exclusive "frequency offset" feature automatically retunes for cable HRC and ICC frequency offsets: 100% error proof so you don't have to remember all those offset channels and frequencies.

Cm•F111.1.0 W..

1— IC: I-1 DC 1-1 1_1 1_11_ _ILI

Oà.0

111,

(DF= 1 woo.. sal]

•••••••.. .•

PER•011.11ANCE nATtA

10 MO44.

FS73 CHANNELIZER JR. —S-1,995 Patents Pending

CHANNELIZER SR. AND CHANNELIZER JR. are trademarks of Sencore Inc

',V 1,1•1• FYI.. • 11111ft,

FS74 CHANNELIZER SR.—S2,995 Patents Pending

Exclusive on-channel automatic signal-to-noise ratio test. Eliminates time-consuming signal comparison and chart reading.

Exclusive audio to video ratio test measures directly in dB for easy comparison to FCC specifications.

Exclusive automatic FCC accurate Hum level test. Eliminates customer down time, speeds your testing, instantly on any channel.

Exclusive signal quality check. Built-in 4 MHz wideband CRT monitor analyzes and pinpoints RF video troubles fast.

Exclusive built-in autoranging AC/DC volt and ohmmeter now measures trunkline voltage through RF input—hassle free.

Exclusive all weather design holds tighter than FCC specifications from —4° to 104°F.

Battery operated for true portability, field tested tough for dependable ease of use and IEEE 488 Bus compatible for non-attended and remote testing.

Or Choose: The All New FS73 "CHANNELIZER JR."TM

If you're looking for the perfect FCC accurate performance tester—the FS73 "CHANNELIZER JR." is your ticket to success. It incorporates all the same exclusive automatic "Signal Quantity" checks as the FS74. It's the perfect performance tester for your van, etc.

Call 1-800-843-3338 for your 15 day free trial. Call us today for a full color brochure or better yet let us put an FS74 or FS73 at your site for 15 days FREE! Discover just what 100% automatic, FCC accurate RF analysis will mean for you—Call today!!

>

Means Success In Electronic Servicing 3200 Sencore Drive, Sioux Falls, South Dakota 57107


Figure 5: RF bypass option block diagram

Cable in

50-550 MHz

RF in RF out r--7 Converter in

•

Relay L

To converter

Playback of a prerecorded VCR tape is ac-complished by tuning the converter to the out-put channel of the VCR and tuning the television to the output channel of the converter. For all other

recording/viewing scenarios, the appropriate channel is tuned on either the VCR or the con-verter with the television tuned to the output chan-nel of the converter. Unattended program record-

ing also is possible on all the clear channels that can be selected with the VCR tuner. Remote control features associated with both

the converter and VCR remain functional for both channel tuning and mode selections. For the television, remote channel tuning is no longer applicable, although volume control is still usable if available. The biggest limitation of this particular con-

figuration is the inability to record a descram bled channel through the converter. This can be over-come, however, by using a baseband converter to loop the converter's baseband outputs back into the VCR's baseband inputs. This approach, in addition to requiring a baseband converter, also requires selecting baseband inputs as the VCR recording source, instead of the usual in-ternal tuner source. Depending on the VCR model, this input is selectable either manually at the VCR or through the remote unit.

In order to record a descram bled channel us-ing a non-baseband converter, the setup in Figure 2 is proposed. Here, the converter is placed in front of the VCR, which in turn is con-nected to the television. In this approach, all channel tuning is performed through the con-verter, since only a single channel is output to the VCR or television. As such, only remote tun-ing through the converter is meaningful. This approach allows the recording of

descrambled and clear channels. The limitation is that only one channel at a time can be record-ed or viewed. This also applies to unattended program recording, because no one is present to change the converter channel.

325 South El Dorado Mesa, Arizona 85202 (602) 966-2931 1 800 528 8224


laqwnN aoptias Jape%

"900L tiloog 'moi4S D'ION ay; le sn aoS

There are exceptions, however. Some of the more advanced converters feature "time-controlled programmability." With this feature subscribers can program converters to change channels in their absence, allowing the VCR ac-cess to record any of the converter's authorized channels. Typically, programming is accom-plished in a manner similar to VCR programming, by specifying the required time, channel and day information necessary to select the desired pro-gram. System "reference time" is supplied either automatically through the headend or input manually to the converter, depending on the par-ticular converter model. This feature greatly enhances the effectiveness of the converter in

situations where unattended channel changing is desired. The configuration shown in Figure 3 expands

upon the basic elements illustrated by the first two figures in order to increase and combine the capabilities of the two. In this setup, the incom-ing cable signal is first split and then fed to both a converter input and one of the inputs of an A/B RF switch. The output of the converter is con-nected to the input of the VCR, with its output con-nected to the other input of the A/B switch. The A/B switch output is connected directly to the in-put of the television. The net effect of this approach is to allow the

subscriber to independently record either a clear

CABLE CONTRACTORS, INC.

851 W. LAKETON AVE

MUSKEGON, MICHIGAN 49441

TELEPHONE 616-759-4594 ,

111

14 ,1 .• .• MI .--% MI

. .ne, '... .

g

- .....,-,4,.. ,

Aerial & Underground Construction ,- . e 4 qW

..4,

..• —..--,--

;Ili; 71 Rai

_

«.

- ....:

Strand Map & Design

,• ,

--- ..-,.ii.im.e:-ito:„: ......-,. e ,... & MDUs

, 1

,fr. , ,-. Installation, Audit

Lakeshore's principal philosophy is that we prosper "because of, and not at the expense of others." When all decisions meet this test, everyone wins.

Aerial 8 Underground Construction • Splicing • Balancing • Activation • Sweep • Installation • Audit


or a descrambled channel, while at the same time viewing a clear channel. In the case of a cable-ready TV, the subscriber can view all clear channels tunable on the television, while record-ing through the converter. For a conventional TV, the subscriber is limited to Channels 2-13. Addi-tionally, the subscriber can view the same descrambled channel that is being recorded through the converter. The limitation for unattended VCR recording

also applies here. Only one converter channel at a time can be recorded unless the converter has the ability to automatically switch channels. Moreover, a new limitation occurs in the case of remote control operation, where the user may have to manually set the A/B switch to the cor-rect viewing position. The extent of this problem is determined by the recording/viewing habits of the subscriber and the desire for truly remote operation. Additionally, there is no remote visual feedback as to the A/B switch position. Chan-nel tuning now is accomplished either via the converter or the television, depending on the selected mode. While providing more capabilities to the

subscriber, there is additional cost associated with the RF splitter and A/B switch required to support these features. There also is an inherent 3 dB minimum loss in the signal level and noise figure associated with the splitter losses. This could become an issue in an area of the distribu-tion network with a marginal signal-to-noise ratio, resulting in degraded picture quality. The approach in Figure 4 overcomes one of

the last remaining obstacles associated with that of Figure 3: the ability to record and watch dif-ferent descrambled (or clear) channels simultaneously. This is accomplished by using an additional converter connected in the alter-nate signal path, whose output is connected to the TV through the A/B switch. Now tuning is con-trolled by individual converters, with the TV stay-

ing on one channel (or possibly two, depending on the VCR/converter output channel compatibility). The same limitations of true remote capabili-

ty, single unattended channel recording, in-creased cost and possible signal degradation apply here. Also, the cost increase is substan-tial because of the second converter. Moreover, the wiring maze can become unsightly and con-fusing as the number of system components grows. In addition, possible interactions could exist between the remote controls of the two con-verters. However, the benefits of this fourth ap-proach are substantial due to the complete pro-gramming and viewing flexibility that is intro-duced with a second converter.

Further complicating all of the previously men-tioned configurations would be the addition of a separate A/B switch in front of the TV to allow for off-air broadcast reception. What is a com-plicated problem now could become even worse with the additional hardware and potential misuse by subscribers resulting in increased signal leakage.

In addition, the high signal levels associated with off-air stations increases the A/B switch isola-tion requirements such that 80 dB minimum would be required in order to prevent local co-channel interference.


The Panasonic PC-200 Addressable Converter.

PAY- PER -VIEW LISTIN GS

MOVIE - II10111Y TO Lic:In

SPORTS - VS Keen

MOVIE NEE IN TOWN

MOVIE - VIO1ITS

Offer more than just the basics...

The Panasonic PC-200 Addressable Converter lets you provide more than just basic cable services to your subscribers. It gives you the tools necessary to deliver a '"11•111111111111111111.11.1Pr.,

new and profitable service to your consumers — pay-per-view television. Naturally, the more services you offer — the more subscribers you'll maintain. Not to mention the additional revenue you'll be generating for your own business. The PC-200 Converter offers you the convenience of instantanèous control of every channel in your system. Plus, an independent Panasonic scrambling system which helps increase system security. What's more, the PC-200 is compatible with gated 6 and 10 dB sync suppression scrambling which means you can hook it up to your present Jerrold system. And, it allows

SAN 30,195 7

mammas

purchase of converters from more than one source. In addition, you also get a host of downloadable parameters. Like channel map, barker channel number, IR enable/disable, and force tune of the converter just to mention a few.

Put the Panasonic PC-200 Addressable Converter to work in your system — we're ready to help you deliver entertainment that's a phone call away. And, address your bottom line, of course.

For more information call: East Coast: (201) 392-4109 West Coast: (415) 672-2592

Panasonic Industrial Company

Reader Service Number 30. See us at the NCTA Show. Booth 2800.

• . •

44

6 •

6

or • • • •

• . 0 , • •

• • . às r • • • ip

• • • •. • 6

o • $ •

Sq O.

1P

•

•

Let's get one thing straight. The C-COR you may have known in the past is history

In its place we've built a new organi-zation. With new management. New ideas. And a new sense of mission.

You might say we're the only new com-pany in the industry with 34 years' worth of

e

• • 11)

• • .... • •

•

experience. A reputation for reliable pro-ducts. And a track record in technological innovation as long as your shirt sleeve.

Appropriately enough, C-COR is a shirt sleeve operation, with dedicated, deter-mined people from the president on down eager to roll up their sleeves and work with

••••-••

you on any size build, rebuild or upgrade project you can name.

Customer service? We're flat-out fanatic about it. This means having a C-COR engineer on your job site, training your own people at your location, so they know the system as well as you do.

• 1 • . le lit.

I • ‘. ' •

• de be

• ••

• 1 e

\ ---y •

' • de• . 4„.

• •

et. • • •

• •

•

.,*

• 1' 11111 • • • • •

' ., '. • 111111• Ie e • • a„ Ilio • . .

• . ,._. 1. d. INV Alit * . ' . • Ii i•

Ill 1

• • • .• • v.

• • % Ilk ..ee .04:1 111 e, .• • • • . / j •• 4 1 t • : e

. ..\i • (ii‘ 6.0. 0* • . ••• 6 -- e . •4" .° • ̀•!1. 6 * ( r .. 2,

•• i .' '*, • • . e • , •

• . .... le

• ' '• • • \3,.. e,

. r • ••• •• e e

' . 0,- . .

r • • • e. -,,, a. te • • -• 60

' 1 *

la * •

114 f •

1

e e • o

Ilk e • •

.

a • 116 :4 4/4. lb

• •

•

aq,

•

• • e . •.\ ; • . • . \ . . .. • • 41 ' •••%.

„ t•'•• ..,. d• .. • • . 4!.. e' . r. • '' ••\. et qi% .... .. ..., •- • %, : s J -% • " \'

, \ , • . .0 o ... r . • 4 "

. • 64 • ll • • . • ,,,• e 4, --% ' I ...... . •

• v. • %.,.. ' .ii ., ,,,,.. • . 1, • ,e

rill' iti:• 111è alti 11‘,04, 1,`', ae 1.. . v• Iwo 4 e :14--.1. r .1.- 44 : • • 4 a • d e 4 P. I/ ' 1 • • e 41 • — 11. Ale 6 t ' •• 0. .'•1* . ' .6" 0 - p' 4 !...„

•‘ • .1.- 0/ •ele" Airs • . • 119 'es go. ' • eill • •

— . s. e 4184 • . •14'•

0 '

. , •••'.• if; P. • - % at . e ' • :It • - •—, •

IIP

91. .

•

•

• • 5

• d

•

••••

•

• • • •

•

•

•

• •

• ... II e

•

• •

•

•

I

•

e•

•

•

-

• • • •

•

.4,

s-

• ,

dos. •

•

•••••. 1/4.

•

You Bylbe Kind Of ReceptionYou Get It means an array of unique,

computer-aided design services that let you test a new system before it's even built, or generate more revenue by squeez-ing as many channels as possible out of your current plant.

And it means a 24-hour hotline, so

you don't have to wait a week for the answers you need today.

It comes down to this. The industry is starting to shake out. When it does, we intend to come out on top.

So from now on, whatever your needs, call us at 1-800-233-2267.0r

write us at 60 Decibel Road, State College, Pennsylvania 16801.We're out to giveym the best reception in the business.

aC011ELECTRONICS INC We're Out lb Givekki

•

Tile Best Reception In The Industry

Reader Service Number 32

TUBES* FAST, LOW COST, 41, ALWIILS,,IcEOCK

8elvd-ïoïNie:glitil2 ALPHA ELECTRONICS

More than 50,000 different types of electron tubes are always in stock...Eimac, Sylvania, General Electric, Amperex, RCA, and all the other major brands. Just a toll tree call away.

Send for a FREE Tube/ID Source Guide am, To: ALPHA ELECTRONICS, INC. Box C

, 136E 39th STREET, BROOKLYN, NY 11218 I PHONE: (718) 633-2800 TELEX: 232463 , FAX: 718-633-4375 I CABLE: ALPHATRANS New York

ICOMPANY. NAME:

CT 5/87

ADDRESS:

The Star of our family ?orabs

much attention... Pat. #4,451,803

"MR BM" COMTRONICS INC.

L- STATE ZIP J EAGLE COMTRONICS, INC. 4562 Waterhouse Rd., Clay, N.Y. 13041

Figure 6: Possible RF bypass option configurations

Cable in

Cable in

1 RF bypass

Cable To in TV

Converter

Cable in

RF bypass

Cable To

in Converter TV

Cable in

•••

Cible -ready Tv

•• •• ••

ffl

Comments: Restores cable-ready capabilities to TV.

Cable-ready VCR

Any TV

• •

• •

• •

URI

Comments: Restores cable-ready capabilities to VCR/TV.

rl, RF bypass

•••

Cable To in Converter TV

Any VCR

Converter #2

Cable. ready TV

•• •• ••

IIIMI

Comments: Res ores cable-ready capabilities to TV (while independently recording any channel).

1 RF bypass

Cable To

in Converter TV

•••

Any VCR

Any TV

URI

Comments: Allows for simultaneous viewing/recording of separate descrambled channels.

The interim solution Building on the capabilities and limitations of

the four basic configurations, and the latter two in particular, some improvements can be made to increase consumer friendliness. These enhancements use the A/B control signal built into most of today's converters to handle dual-cable systems. While actual dual systems are in a minority, this control signal and its inherent capabilities can be used to benefit the majority of subscribers and minimize their interface frustration. The majority of the A/B control signals on to-

day's converters are present either as logical con-trol signals on the RF input connector for an ex-ternally powered electronic relay or complete converter-powered A/B relay drives. In the latter instance, no additional relay powering is required and the A/B switch attaches directly to the con-verter. This is controllable via the converter (or remote unit) A/B control button. In the former, a wall-mounted transformer also may be required to provide the drive capability from the converter control signal. Using this inherent control and drive capability presents two possibilities to resolve the consumer interface issue. The first, illustrated in Figure 5, combines the

splitter, switch and capabilities of the configura-tion in Figure 3 into a self-contained unit for at-tachment and powering directly off the converter This approach, or so-called "RF bypass," allows the converter to be electronically switched in an out of the signal path via the converter or its

...the rest of us joined together to get the attention we deserve.

The Eagle trap is the biggest selling and best known product manufactured by Eagle Comtronics. In fact, since the advent of cable television, it has constantly held the spotlight as the most popular CATV security device in the industry

But Eagle Comtronics manufactures an entire family of superior CATV security devices and distribution pro-ducts. And though they may not be as well known to you as the trap, they are all cast from the same proven mold.

Programmable and Addressable Descramblers, Headend Scramblers,

Remote Computer Slave Control, Test Equipment. MADE IN USA.

Traps, Decoding Filters, Multiple Channel Traps, High & Low Pass Filters, Brass & Plastic Shields, Security Tools, IF & RF Encoders and Lower Adjacent Sound Oscilla-

tors. MADE IN USA.

Jel „taw, Batch Descramblers, Band Pass Filters

and Video Amplitude Controller. MADE IN USA.

2, 4, and 8-way Brass "F" Port Directional Taps'-100% Pressure Tested & Polyurethane coated. MADE IN USA. Splitters. • Pat. #4,311,974

COMTRONICS INC.

Meet the Family EAGLE COMTRONICS, INC. 4562 Waterhouse Road, Clay, New York 13041.

TO ORDER, CALL TOLL-FREE: 800-448-7474 In New York, call 315-622-3402 In Canada, call Deskin Sales, 416-475-1412 In Europe, call Electro Service, Brussels, Belgium, 011-32-15-209575.


Figure 7: Output A/B switch option block diagram Cable in 50-550 MHz

Antenna in

RF in 1- 1

To TV From

r---1 converter

Relay

To converter

Figure 8: Possible output A/B switch option configurations

Cable in

Cable in

yAntenna

Cable in

Converter

To TV

Splitter

Cable in

Cable

in Converter

To TV

Splitter

Cable in

•••

Any

TV

Comments: Allows reception of off-air channels

Cable-ready VCR

Any

TV

•• •• ••

E

ffl

Comments: Restores cable-ready capabilities to VCR/TV.

A

• • •

Cable To

in Converter TV

Any VCR

Converter #2

I II

Cable-

ready TV

• •

• •

• • • •

E-ffl ffl

Comments: Restores cable-ready capabilities to TV (while independently recording any channel).

Output A/B ,e,tcn rL

Cable To in TV Converter

•••

Any VCR

Any

TV

•• •• •• ••

Comments: Allows for simultaneous viewing/recording of separate descrambled channels.

remote control using the A/B switch button. This then returns full use of a television's cable-ready capabilities by making the converter transparent to the system when scrambled channels are not involved. Several potential uses are illustrated in Figure 6. The second potential use for the A/B drive cir-

cuitry is shown in Figure 7 and functions as an output A/B switch. This concept builds upon the capabilities described in Figure 4, where a separate input to the television is required for the second converter. Use is not limited to a second converter, however, as illustrated in Figure 8, where several alternate uses are described. Most notable is the first, which would meet the newly adopted FCC A/B switch option requirement.

Both concepts help minimize the wiring maze by reducing the number of necessary device in-terconnections. Remote control operation also is returned to the subscriber through remote switching of the converter A/B remote control unit. Similarly, a visual indication of the subscriber-selected mode is now available through the converter's A/B mode indicator. For those converters with a built-in A/B drive, either of these devices are field upgradable without opening the converter and can be installed by the subscriber on an as-required basis.

Going forward In the longer term several approaches to the

ultimate solution are under investigation. The primary focus is to remove most, if not all, of the converter electronics from the home and rely on the cable-ready VCR/TV tuning capabilities for channel selection. Two major efforts now under way attack the problem from different directions. From the front end, several off-premises

technologies are undergoing development and evaluation. Pay service authorization is controlled either via external jammers, traps or decoders employing passive, non-addressable technology or active addressable methods. Although the costs have now been removed from the home, penalties associated with outdoor environments have to be considered as well as flexibility for add-ing impulse capability as the need arises. In ad-dition, as with any new technology, field per-fomance has yet to be established under actual operating conditions. For subscribers without full CATV tuning capabilities in the VCRs or televi-sions, plain converters also would have to be pro-vided to accommodate necessary tuning. Coming at the problem from the other direc-

tion is the IS-15 standardized multiport interface to be included in future VCR and TV products. This interface provides the necessary baseband signals for premium channel descrambling and relies on the VCR or TV tuning capabilities for channel selection. This could ultimately result in a lower cost decoder by removing the necessary tuning hardware. Although several VCR/TV manufacturers have announced that they will have IS-15 hardware available shortly, it may be some time before its acceptance is widespread.

Undeniably VCRs and other cable-ready con-sumer electronics are a force that must be dealt with in today's cable marketplace. How effective we are at interfacing our systems to the subscriber's electronics may ultimately deter-mine our success or failure as a business.

3E3 MAY 1987 COMMUNICATIONS TECHNOLOGY

• •

0 ffffff

S ANCIARD

STAN1pARD

SATELLITE VIDEO RECEIVER AGILE 24S

e • • AL0.0

SATELLITE RECEIVER

•

e AGILE 24M

e ef moat •

rowz of

Cu MH,

7'fff

Cu MHz

GROWING BIGGER SHOULDN'T MAKE YOUR SIGNAL GROW WEAKER

With Standard's Agile 24 receiv-ers' loop-thru IF circuitry, upgrading your system doesn't have to mean degrading your signal, blowing your budget, or accumulating lots of downtime.

Instead of replacing your present 4-way splitter with an 8-way splitter, thus attenuating your 4 GHz signal output by half, Standard's loop-thru feature allows you to maintain full power as your system expands.

All your need is a one-port jumper from your splitter to our Agile 24M master receiver.

Our loop-thru feature lets you drive up to 12 Agile 24SB slave units from the master without expensive power dividers, and without losing signal strength.

4 WAY POWER DIVIDER

TO AGILE 24M

BRAND X RECEIVER

BRAND X RECEIVER

STANDARD AGILE 2458

STANDARD AGILE 2488

Our most relied-upon receiver Known industry-wide for depend-

able operation, the Agile 24M is a dual-conversion 4 GHz receiver that

block downconverts to 760-1260 MHz. Its active loop-thru design sup-

plies the entire 500 MHz wide block of frequencies to Agile 24SBs.

The Agile 24M's phase-locked loop synthesizer and effective AFC circuit combines with a temperature-stabilized dielectric resonator oscil-lator (DRO) to ensure rock stable operation. In areas where microwave interference is a problem, optional 60 MHz and 80 MHz filters can be easily installed.

Simple installation, testing and maintenance

The Agile 24 MISB Series fea-tures a low-profile 1314" chassis that occupies a single rack space. The front panel includes a three function meter that displays signal strength, C/N, and center tune; as well as convenient test connections and performance adjustment controls. It is Video-Cipher Ir tested and approved for all programs being scrambled.

Backed with the industry's strongest warranty/replacement program

Our satellite receivers are built to last, and our warranty program shows it.

If a unit fails, call us and an immediate replacement will be shipped within 24 hours.

If it's within our one-year war-ranty, the replacement is free. Within years two through five, the replace-ment is only $100.

For more information on improv-ing your system, and on the full line of Standard Communications TVRO products, call us toll free at 8001243-1357 (in Calif. call direct, 2131532-5300, ext. 275), or mail in the coupon below.

Standard -1 Communications SATCOM Division P.O. Box 92151 Los Angeles, CA 90009-2151

Engineered to a new standard

I'm planning to add satellite channels E Please send me a detailed brochure E Have a sales representative call

Name

Title

Company

Phone

Street

Lty

CT 5 87

State Zip

See us at the NCTA Show . Booth 1626. Reader Service Number 36.

The VCR interface By Michael E. Long

C"AI Zenth Electrorucs Corp

Industry sources estimated that at the begin-ning of 1986, 28 percent to 30 percent of American homes would have VCRs. This represented a 10 percent increase in VCR market penetration from 1984 to 1985. It also has been reported by some MSOs that nearly 60 percent of their subscribers own VCRs. An A.C. Nielsen study similarly showed that pay-cable subscribers are most likely to own VCRs. Clear-ly, the home video recorder is an important ele-ment to be dealt with in the design and marketing of a cable system Whether the VCR is a friend

or a foe, an opportunity or a problem, depends on how the cable operator reacts.

For existing or potential subscribers, cable TV is regarded as a service for which they pay depending upon its desirability, quality and usefulness. The perceived usefulness of cable is largely based upon its economy, convenience and ease of use. Its desirability stems from pro-viding a greater variety of programming than is available from off-air TV or other alternate enter-tainment sources Since cable does provide such programming on various and sometimes con-flicting schedules, the subscriber often wishes to record programs on the VCR for later view-ing. Here begins the problem.

Figure 1: VCR connected before decoder

CATV in

• • •

VCR

Ch. 3

Decoder

1

TV receiver

Figure 2: VCR connected after decoder

CATV in

Ch 3

V Decoder

Ch 3

I 1 • • •

VCR

TV receiver

'The cable operator now must consider the VCR as one of the system parameters and deal with it'

Faced with the various interconnection possibilities of cable, converter/decoder, VCR and TV receiver, consumers often become frustrated and intimidated by the seemingly com-plicated arrangement. Once connected, subscribers find that they either cannot record premium (scrambled) programming or are on-ly able to view the program being recorded. It has greatly reduced the usefulness of the VCR's features.

In order to maintain subscriber service satisfaction, the cable operator now must con-sider the VCR as one of the system parameters and deal with it. A low-cost, easy-to-use VCR in-terface device must be provided to help subscribers solve their problems. For maximum utility, the ideal device should provide the follow-ing functions:

1) simple, easy-to-understand operation 2) maintain MIS stereo compatibility 3) maintain performance quality 4) maintain unattended VCR programmability 5) allow ability to:

a) view recorded tape b) record premium while viewing the same premium channel c) record basic while viewing the same basic channel d) record basic while viewing other basic channel e) record premium while viewing basic channel f) record basic while viewing premium channel

Common approaches It seems that every technically minded in-

dividual in the cable industry has thought of a different answer to the CATV/VCR interconnect problem. Some solutions appear simple and


WE'R HER

E E

TO STAY

Miner cable equipment, inc.

969 Horsham Rd. • Horsham, Pa. 19044 Call Toll-free 800-523-5947

in Pa. 800-492-2512



Figure 3: External splitter/switch

others very sophisticated. A common problem is that these devices sometimes are considered from an engineer's point of view and not from the end-user's. RF switching systems designed to provide for

every possibility may be technically elegant and have great appeal to the cable operator's engineering staff but they can be a "headache" for the consumer in installation and use. Even after the device is correctly installed, the

subscriber must learn what switch to turn to what position, and what channel to be tuned on both the VCR and TV set for each seemingly simple desired function. Beyond this, the prospect of teaching the use of the device to other family members or an occasional babysitter becomes a monumental task. Up until now, the two major approaches to the

VCR/CATV interconnect problem have been hard-wire interconnect and RF switching. Hard-wire interconnect:

Figures 1 and 2 show the two possible methods to interconnect a CATV cable, con-verter/decoder, VCR and TV receiver without ex-tra devices. In Figure 1, the CATV decoder is con-nected between the VCR and the TV set. This arrangement allows the full use of the VCR's features to record any basic program while view-ing any program, basic or premium. The VCR's programmability for unattended channel change is retained but premium programs cannot be recorded, since the signal does not pass through the decoder until after it has passed through the VCR.

In order to record premium programs, the VCR must follow the decoder as shown in Figure 2. This arrangement renders most of the VCR's tuner features useless, however, since the VCR only can receive the output channel of the CATV decoder. RF switching: An alternate approach, designed to recover

some of the VCR features lost in the hard-wire interconnection, is shown in Figure 3. This system uses an external splitter and RF A/B switch ar-

LOOK NO FUR'THER...

WE'VE GOT ALL YOUR CATV REPLACEMENT PARTS IN STOCK AT LOW, LOW PRICES!

ALL MAJOR MANUFACTURER'S EQUIPMENT & ACCESSORIES

Specials

MHW1342's Only $265° CA 2301's Only $250° CG 145L's (Clip-ons, too)

Only $ 125

ORDER TODAY! Call Glen Haimes, Nat'l Sales Mgr.

TOLL FREE: 800-645-2300 In NY: 516-599-6400/Fax: 516-599-6495

Save with

Mk am-J....Ca Tenrrtrian 15 MAIN STREET EAST ROCKAWAY, NY 11518


* :•:.

$ Reader Service Number 39. $ :•:. e. ...

e

... •:.

:!›.»5›:•:•:•:•:•:•:•••...,eeeee«:?:•:•:•:•:•:•:•:•:•:•:•:•:•:•:-...-.-e.w.w.w.we.yee.w.m:e

S"We are not selling, We are buying."

«Zio

r ril-4 k k ,

RESOURCE RECOVERY SYSTEMS

Nationwide purchasers of scrap, wreckout and clean coax.

TOM WOOD, Sr., Marketing Mgr. 11373 Southton Rd.

San Antonio, Texas 78223 (512)633-0630

TOM WOOD, Jr., Accounts Mgr. 14127 Langbourne

Houston, Texas 77077 (713)493-5158


GET HOOKED ON OUR HOOKUPS

VIEWSONICS FM STEREO TV and VCR HOOK UP KITS

are "SUBSCRIBER FRIENDLY"...and will save you installation costs.

VSMTV-1 for one way 550MHz systems

VSMTV-2 for addressable one-way 550MHz systems

Includes (1) FM Stereo TV, 550 MHz splitter or coupler, (1) 1 foot and (1) 12 foot highly shielded coaxial cable with connectors, (1) matching transformer and (1) A/B switch.

VSVCR-2 Includes (1) AB Switch, (1) 550MHz Splitter, (3) highly shielded coaxial

cables with connectors.

Each kit contains an easy-

to-use, pictorial instruction

booklet.

We can customize kits with

your own name, logo and

price on the header card

and instruction booklet or any variation in components.

1011 Viewsonics "PROFIT FROM OUR EXPERIENCE"

Inc P.O. Box 36 • Jericho, N.Y. 11753 Call Toll Free: 800-645-7600 In New York Call: 516-921-7080

Se • us at the NCTA Show. Booth 2912. Reader Service Number 40.

Figure 4: View/record switching

CATV in

Decoder

Premium

CATV (!) VCR

View

CATV

Record P,

TV receiver • • •

VCR

Figure 6: Video/audio—RF switching

CATV in

Decoder

ranged in such a way that while any program (basic or premium) is being recorded, any basic program can be viewed. The VCR. however, still Is only capable of receiving the CATV decoder's output channel and is incapable of program-mable channel change. Operation of the system now begins to become complicated due to the addition of the manually operated A/B switch. As an attempt to recover more of the func-

tionality of the VCR, an RF switching product in-corporating multiple ports, switches and splitters can be used. Figure 4 describes a typical prod-uct incorporating two separate switches, one for viewing (three positions: CATV, premium, VCR) and one for recording (two positions: CATV, premium). Although this approach does seem to provide for all of the most desired options, it does not allow a programmable unattended VCR to record a premium program followed sequen-tially by recording a basic program since the VCR has no control over the switching. Additionally, the manual switching is more complicated and might tend to intimidate many high tech-shy subscribers.

In an effort to simplify the switching device operation, the RF switches could be ganged together as shown in Figure 5. This arrangement Is designed to reduce the possible switch posi-tions, and consequently the number of decisions the user must make.

This example shows a product with only two positions. Position A allows the viewing of any basic or premium program through the use of the CATV decoder tuner, while recording any basic program through the VCR tuner. Position B allows the viewing of the VCR output or any basic or premium channel tuned by the CATV decoder tuner, while recording the same pro-gram being viewed. A third switch position could be added, with only a small increase in complex-ity of operation to further allow the recording of a premium program while viewing a basic program. Even though these solutions appear to simplify

operation, switch position and channel selection decisions still have to be made depending upon what the subscriber desires to do. In some switch positions, checking what the VCR is recording is impossible, since switching to the "VCR view" mode disconnects the desired signal from the VCR input. Similarly, care must be taken not to change switch positions for viewing alternate pro-gramming while VCR recording is in progress.

Figure 6 shows a novel approach using both a two-position RF switch device and the video/audio outputs of a baseband CATV decoder through the VCR's built-in tuner/auxiliary input selector. Some new VCRs even allow the unattended selection of tuner or auxiliary inputs as part of the multi-event programming. With such a VCR, this system allows for all of the desired functions. In operation, however, it is not as simple as it looks. Although there is apparently only one two-position RF switch to be concern-ed with, there are two more two-position switches in the VCR (TV/VCR switch and tuner/auxiliary switch) that must be manipulated.

Alternate approaches RF switching systems have one common

drawback—the complicated installation and


solves the pay-per-view

puzzle. Pay-Per-View is here and growing

fast. Last year alone, the number of homes able to receive PPV service doubled and PPV revenues soared.

If you're considering Pay-Per-View but are puzzled about which technology is right for you, consider the benefits of Impulse Pay-Per-View with General Instrument's TOCOM 5503-VIP converter •1DCOM 5503-VIP addressable converters are impulse-ready NOW, eliminating converter obsolescence. • Instant access to PPV programming via the TOCOM 5503-VIP remote gives subscribers the convenience of arm chair ordering, generating higher buy rates. • The TOCOM 5503-VIP uses field-proven store-and-forward technology, providing last minute ordering capability without peak load constraints. • TOCOM's fully integrated software and system support is compatible with most major billing systems, PPV programming services and PPV ordering methods.

Get in on PPV * profits now with the TOCOM 5503-VIP — the Impulse converter that easily solves the Pay-Nr-View puzzle.

TDCOM Impulse can be implemented in your system today! To find out how, contact your Jerrold Account Executive or call the General InstrumentrIDCOM Marketing Department at 214/438-7691.

GENERAL INSTRUMENT Reader Service Number 41.

various switch positions make them difficult to use. What really is necessary is a system that does not require the subscribers to think about what they are trying to do.

In an effort to provide the most user-utility, while providing simplicity of operation, two alternate approaches to the VCR/CATV interconnection problem are suggested: the VCR "afterburner" baseband decoder and RF frequency multiplexing.

The afterburner approach is so named because the premium program descrambling is performed after the subscriber receiving equipment's tuner-IF and demodulation stages. The system depends upon baseband scram-bling techniques, in-band addressing data and home equipment capable of being adapted.

Figure 7 shows a VCR equipped with a Zenith Base-Tac decoder. (All Zenith VCRs since 1984 have been adaptable to a Base-Tac decoder

through a field installable Redi-Plug. Similarly, a VCR designed with a Cenelec connector for the NTSC television receiver baseband audio/video interface standard could be used.) The plug on the back of the VCR contains all of the necessary interconnects in a single, multi-wire cable between the VCR and the Base-Tac pay TV decoder.

In this approach there is no CATV converter (only the baseband decoder), no splitter and no RF switches to be concerned with. The CATV RF signals can be connected directly to the VCR and from the VCR to the TV receiver as in a normal setup. The VCR tunes and demodulates the en-coded channel into a baseband signal. The en-coded video and addressing data then are routed to the external baseband decoder through the plug. The decoder, if previously ad-dressed and authorized for the tuned program, will decode the signal and return it to the VCR. Channel selection for the VCR is accomplished

through its own tuner, manually or via its pro-grammable VCR timer. The VCR and TV receiver operate normally without complicated switching and retain all of their features, including BTSC stereo compatibility.

Since the "afterburner" system relies upon baseband scrambling and adaptable home equipment, it may not be a univerally acceptable solution to the CATV/VCR problem at this time. A more general approach is needed to deal with the variety of equipment now in use. Thus, a VCR interface was conceived by Zenith that does not require manual or automatic switching but sup-plies all of the functions normally associated with

Introducing The Highly Flexible 4 Channel System

VTS MODEL 464 AUTOMATIC COMMERCIAL INSERTER

SPECIAL INTRODUCTORY PRICE OF *$5,686.00

f.•••••••

•••....

._••=tea.

OOOOO bt

•••

• Cost Effective • 4 Channel System, 2 Insert Selectors • Dual DTMF Decoders - One for Network, One for Off Tape Tones • Switch Selectable Pre-Roll Time 8( Audible - Inaudible Tones • Selectable Network Codes

«NO MP. Vella. Made •••

• Automatically Utirzes Network Breaks (Including Variable Lengths of MTV, VH-1, 8( USA) • Automatic Net/Local Switch if all Criteria is Met • TNN Output Command for External Audio Switch

Lease/Purchase Available, for Further Details Call:

VIDEO TAPE SYSTEMS, INC. (205) 533-5138 Reader Service Number 42 727-E Arcadia Circle, Huntsville, AL 35801

'Introductory Price Expires July 31. 1987

('u-ser 'frend-le) adj. 1. Fast cable hook up 2. Easy cable operation

Is Your Cable System on the Road to "User Friendly"

3. Attractive casing 4. Best prices 5. Best specifications 6. Best delivery.

('kWill-tar) 11. 1. Orginator of the Video Control Center VCR Interface Switch 2. Recognized leader in the Cable Industry 3. Supplier and private labelers for Cable Industry leaders such as Gill Cable, Jones Intercable, Falcon Cable, Storer Cable, United Artist Cable, Bismark Mandan Cable and many more.

IlalliMMION/IIM Mai /Walk

IIleNEW /111011/N NEW . QUALITY SYSTEMS FOR TODAY S TECHNOLOGY

P.O. Box 6579 Westlake Village, CA 91359

(800) 257-7889 in CA (800) 572-6262

or (818) 706-1940 See us at the NCTA Show, Booth 104. Reader Service Number 43.

such switchers. The application block diagram of the system

is shown in Figure 8. With this approach, instead of switch/time multiplexing the RF signals through a difficult to learn switching system, the signals are frequency multiplexed. The incom-ing cable signals are amplified (to compensate for later losses) and split four ways: to a secon-dary RF output, to the input of the primary pay TV decoder, to an FM receiver output and to a

signal combiner. The Channel 2 or 3 pay TV decoder RF output is fed to an upconverter (mix-er/local oscillator) where it is converted to a chan-nel not used on the CATV system. This decoded and upconverted channel now is recombined with all the signals on the cable system in the signal combiner and passed on to the subscriber's VCR and TV receiver. With this arrangement, the subscriber

operatesthe VCR and television normally, in the

Figure 9: VCR interface block diagram

Auxiliary CATV out

CATV n

CATV in

To CATV decoder

Output to FM

Filter

Filter 2-way

Filter

combiner

Ch 3 UHF upconverter

receiver

To VCR and TV

SAWR oscillator

680 MHz or 704 MHz

same familiar fashion as without a CATV con-verter. No confusing RF switching is necessary. No extra thought is necessary to perform the desired viewing and recording functions. Once connected, the VCR interface does not have to be worried about; it can be left out of sight. Channel selection for viewing or recording is

accomplished with the television's and/or the VCR's tuner. With the TV set or VCR tuned to the decoded upconverted channel, channel selec-tion is performed through the CATV con-verter/decoder. Viewing of one channel while recording another is now possible, as well as unattended, programmed VCR channel swit-ching from premium to basic. By interconnec-ting several TV sets or VCRs, a subscriber could

be viewing a premium program and recording a basic program, while others in the home are viewing or recording other basic programs. A major decision is the choice made for the

upconverted output channel. For economical mass-production, a common, standardized out-put channel must be selected. Ideally an unused CATV band channel would be chosen, but due to the lack of standardized channel usage among cable systems, a common channel cannot be identified. An alternate method is to upconvert to a UHF

channel. This serves a dual purpose: It provides a guaranteed unused channel for use and it becomes useful with older non-CATV compati-ble televisions and VCRs.

Figure 9 shows a detailed block diagram of the VCR interface. A SAW resonator oscillator (for stability) is used to upconvert the decoder out-put channel to a UHF output frequency. Two models are made available depending upon the UHF output channel required in the user's area. A 680 MHz oscillator is used for upconversion from Channel 3 (VHF) to Channel 59 (UHF). Similarly, a 704 MHz oscillator is used to up-convert from Channel 3 (VHF) to Channel 63 (UHF). In either case, the converted decoder out-put signal is summed with the CATV RF spec-trum for delivery to the subscriber's VCR and TV.

In application, the television and VCR are placed in the "TV" mode (as opposed to the "CATV" mode) to select VHF basic channels or UHF CATV programs (as tuned through the CAN decoder). Viewing or recording other CAN channels while the CATV decoder is otherwise being used requires switching the television or VCR to their "CATV" modes. 11

Acknowledgements: The author would like to thank Vito Brugliera and George Green for their help and encouragement in the preparation of this paper, and to George Hoeltje, Mike Nakanishi and Andrew Babchak for their development of the VCR interface from an idea to a working product.

References 1 .•Getting Friendly with VCRs." John Motavalli. CableVi-

sion. Oct. 28. 1985. pp. 40-48. 2. "Proposal: Wideband Cable Feed Including

Descrambled Premium Channel," David Large, NCTA Consumer Interconnect Subcommittee. Aug. 21, 1985.

Reprinted with permission from the National Cable Television Association's "1986 NCTA Technical Papers."


Broadband: For the best in distribution amplifiers

Broadband Engineering offers a distribution amplifier for every application from the lowest cost to the highest performance CATV, MATV and SMATV installation.

Flexibility to meet demanding system require-ments is our goal with:

• Bandwidths up to 550 MHz • Gains from 14 to 50 dB • One and two-way operation • Sub, mid and high-split options • Standard or power doubler hybrids

Extruded aluminum housings insure

excellent heat transfer from active devices for long life and reliable service.

And we don't forget maintenance either. Our hybrids are installed in sockets so that replace-ment is quick and easy and down time short.

We don't cut corners in design, we engineer the best.

For more information, call Broadband Engineer-ing at 800-327-6690 (305-747-5000 in Florida) or write us at 1311 Commerce Lane, Jupiter, Florida 33458.

For quality, performance and service, call Broadband

UGH BROADBAND Quality and Innovation

See us at the NCTA Show. Booth 3322. Reader Service Number 44.

Implementing BTSC stereo in the headend Several cable systems have begun delivering pro-gramming to their subscribers in BTSC stereo. Within a few years, most cable systems will add BTSC stereo to their video channels. One prob-lem, however, is that BTSC is a new technology. There is confusion among cable engineers con-cerning both what the technology entails and how to successfully implement stereo in the headend. This article will define the BTSC signal and discuss ways to add the stereo encoding equipment to your headend. You will find that with proper planning, BTSC is easy to interface with your existing equipment and will be a positive addition to your programming.

By Steve Fox Manager. Customer Applications Wegener Communications Inc

When the BTSC concept was initially developed, several design constraints were taken into account: The stereo signal could not disrupt monaural audio reception in subscriber televi-sion sets; the stereo signal had to fit within the 6 MHz video bandwidth; and the system need-ed to deliver quality sufficient to gain consumer acceptance. The system eventually accepted and endorsed by the FCC and the NCTA meets these criteria.

Figure 2: BTSC and FM stereo from a subcarrier audio demodulator

Video

Satellite receiver

Left Corn- audio posite

Base ucuuuuuuiatui

band Right audio

Left Right audio audio

To FM combiner

To TV combiner 4

TV modulator

Video plus 4.5 MHz

or BTSC audio

Figure 1: BTSC baseband signal

50 kHz

25 kHz

Aural carrier deviation

L R

Main Channel

Pilot

L R

Stereo sub-channel

AM-DSB-SC (encoded)

Second audio program (SAP)

2f H 5f H

Baseband frequency (fH = 15.734 kHz)

Professional channel

6.5fH

First, let's look at the BTSC baseband signal shown in Figure 1. The BTSC signal is made up of five components: L+R or monaural, the pilot, L—R or the stereo subchannel, second audio program (SAP), and the professional channel (PC). The L+R subchannel is identical to the

monaural baseband audio signal delivered in monaural-only programming. The signal has 75 ¡is pre-emphasis, 25 kHz peak deviation and a useable audio bandwidth of about 50 Hz to 15 kHz. The pilot carrier is used as a synchronizing fre-

quency for the L—R subchannel and to illuminate the"stereo' . LED on subscriber stereo decoders. Peak deviation is 5 kHz and center frequency is 15.734 kHz, the same as horizontal sync. The L—R (or stereo) subchannel is an AM dou-

ble sideband suppressed carrier with dbx com-pression, 50 kHz peak deviation. and 50 Hz to 15 kHz useable audio response. Total peak deviation for L+R, pilot and L—R combined is 55 kHz. SAP is a monaural signal that is similar in usage

to an FM broadcast SCA. Also dbx compressed, SAP has a 50 Hz to 10 kHz audio response and 15 kHz peak deviation. This signal is intended for alternate language audio (no doubt other uses also will be found that are undefined at this time). Probably, most cable systems will not use the SAP carrier. PC may be used as a voice or a low-speed FSK

data channel and will find use in broadcast televi-


WAv -rEK

SAM II The industry's best signal analysis meter just got better.

Introducing the SAMME 600. Everything the SAM Ill is, and more. A frequency range of 4 to 600 MHz. Microprocessor controlled. Soft-touch keypad. Preprogrammed Video/Audio frequencies and channel assign-ments in Standard and HRC for-mats. "NEXT" key for automatic incremental up-channel tuning. Internal reference for tempera-ture variations.

The SAMME 600 quickly measures Hum modulation, and can accommodate spectrum analyzer display on an asso-ciated X-Y oscilloscope.

For the CATV system engineer looking for the best signal analysis meter, there's only the SAME 600.

For more information call us toll free, 1-800-622-5515. Or write Wavetek Indiana, 5808 Churchman, P.O. Box 190, Beech Grove, IN 46107.

E.600MHz

See us at the NCTA Show, Booth 1722/23/24.


Figure 3: BTSC and FM stereo from a descrambler (full-time scrambling) with local commercial insertion

Satellite receiver

o -o 5

VideoCipher descrambler

Control

Left audio

Right

audio

Left audio

FM stereo modulator

Audio t A

Right audio

Video

FM * To combiner

tcontrol

BTSC stereo modulato

t B ce:D)

Conrol

Audio

Cue source

o

VCR controller

Video plus 4.5 MHz

or BTSC audio

.A Audio

Video

Audio Control e,

TV modulator

VCR

B Control

sion stations. Total BTSC signal bandwidth with all carriers, including SAP exceeds 100 kHz and peak deviation is 73 kHz. (These specifications will take on greater significance when we discuss interfacing the BTSC encoder with TV modulators.) It should be noted that as SAP and PC are added to the BTSC stereo signal, the

potential for signal degradation increases. Therefore, these signals should not be added to your system unless needed.

Next, let's look at the equipment required at the headend to generate BTSC stereo. Three signals drive the BTSC encoder: left audio, right audio and baseband video. Audio sources in-

dude satellite and microwave subcarrier demod-ulators and the VideoCipher descrambler. Video is derived from the descrambler or from a satellite or microwave receiver and is used to generate a reference pilot for the subscriber BTSC decoder. Note in Figure 1 that all signals above L+R are centered at multiples of the 15.734 kHz pilot frequency, another reason for the video in-put to the BTSC encoder. For this reason, a clean baseband video source must be used, not the output of a headend scrambler. The final com-ponent is the BTSC encoder itself. The nomenclature "BTSC" is very important.

Another commonly used term, "MTS" or multichannel television sound, is properly de-fined as stereo transmission on the video chan-nel by some undefined method. "BTSC" is the specific method of stereo transmission endorsed by the FCC and the NCTA, and is the industry standard. Consumer receiving equipment con-forms to the standard or, in other words, are BTSC decoding devices. The point here is that BTSC encoders—but not necessarily all MTS encoders—will operate successfully with con-sumer decoders and should be used in the headend.

To further complicate the issue, the terms BTSC and MTS sometimes are used interchangeably to denote a true BTSC system. True BTSC en-coders provide quantified, measurable perfor-mance standards because they themselves con-form to the industry standard. Non-BTSC stereo

(Continued on page 70)

BTSC STEREO GENERATOR FULLY DBX®COMPANDED

INTERNAL 4.5 MHz MODULATOR DEVIATION CALIBRATION TEST TONE

EXCEEDS ALL OST60/BS1 5 REQUIREMENTS LOW PROFILE 19" RACK MOUNTING

FOR YOUR FREE COPY OF" IMPLEMENTING STEREO TV" CALL OR WRITE TODAY!

TRIPLE CROWN ELECTRONICS tOô te.1

NO., 'III NICK gle

51.110 Oft

POWER

• BISC STEREO GENF* ATOR SG 48

.- TRIPLE CROWN \ ELECTRONICS 4560 Fieldgate Drive, 601 Fairway Drive, Mississauga, Ontario L4W 3W6 Deerfield Beach, Flordia 33442 (416) 629-1111 (305) 429-0870 800-387-3205 (U.S. Only) Inwats 800-824-4332



Unprecedented Performers!

The A-8000 Spectrum Analyzer. A step beyond the

A-7550.

Now 2.6 GHz frequency coverage!

Fully synthesized. Tracking generator.* Quasi-peak detector.*

Truly portable. And again, an exceptional value!

The new A-8000, quite simply put, is our response to industry's demand for a higher frequency, yet still econom-ical, Spectrum Analyzer.

Now, with two models and seven options to select from, you can custom configure the unit that meets your

specific testing requirements.

The commonality of the A-8000 and A-7550 offer you

many benefits. Two powerful microprocessors, menu driven display modes and single function keyboard entry

aid the user in the operation of all analyzer functions. To further increase the operational simplicity of the A-8000 and A-7550, the microprocessor systems automatically

select and optimize the analyzer's bandwidth, sweep rate and center frequency display resolution, with manual override if desired.

Increased flexibility...added features...and exceptional value continue to make IFR the logical

choice when considering your next Spectrum Analyzer. Contact your ¡FR distributor or representative

for a demonstration.

A-8000 and A-7550 Features — All Standard: Fully synthesized (A-8000) 10 kHz to 2.6 GHz (A-7550) 10 kHz

to 1 GHz VRSTM (Vertical Raster Scan) CRT display Single function keyboard entry Menu driven display modes Automatic amplitude calibration Selectable linear/log display

modes Digital storage of all displayed parameters 70 dB dynamic range 300 Hz resolution bandwidth Selectable scan widths, 1-2-5 sequence + 0 and full scan Accurate center frequency readout Direct center frequency entry Automatically scaled electronic graticule Variable top scale

reference (+30 to —95 in 1 dB steps) IF gain in 1 dB steps Line, bar, average, compare and peak hold display modes • 300 Hz and 30 kHz video filters 106 to 266 VAC operation without switching • 12 to 30 VDC operation

*Optional Features Include: • Internal rechargeable 5 APH battery for truly portable operation • Internal tracking generator with 1 dB step attenuator FM / AM / SSB receiver IEEE-488

interface bus RS-232 interface bus 750 adapter Internal quasi-peak detector

—11P—

e IFR SYSTEMS, INC. 10200 West York Street / Wichita, Kansas 67215-8935 U.S.A. 316 / 522-4981 / TWX 910-741-6952


INTRODUCING WHEN

STANDARD JACKET IS TOO LITTLE PROTECTION AND ARMOR IS TOO MUCH.

Until now, if you needed extra protec-tion for cable, you had only two choices.

You could pay the price and buy ar-mored cable. Or you could settle for less pro-tection and buy standard jacketed cable.

New Cable Guard gives you a wel-comed alternative—extra protection at an economical price.

Cable Guard starts out with the same fine electrical properties as all our cable. Then we add a flooding compound and a Linear Medium Density Polyethylene jacket. Next, e add 50 mil splines, angled at 60 degrees r extra resiliency And finally, we en

•

:ABLE GUARD. Linear Medium Density Polyethylene Outer Jacket

Linear Medium Density Polyethylene Inner Jacket

Linear Medium Density Polyethylene Cushioning Splines

Believe it or not, Cable Guard outper-forms armored cable in most impact tests. Yet, it's as flexible as standard jacketed cable.

So, the next time you're running cable through rough terrain—under gardens and lawns, through roadside right-of-ways, or in tough urban environments—ask about Cable Guard.

It's a small price to pay for a lot of protection.

For more information, please contact your Comm/Scope Representative or call us direct at 800/982-1708 (800/279-6808 in NC).

COMM /SCOPE. WITH YOU ALL THE WAY. Comm/Scope Division, General Instrument Corporation, PO Box 1729,

GENERAL INSTRUMENT



Figure 4: BTSC and FM stereo from a descrambler and sub-carrier demodulator (part-time scrambling)

Satellite receiver

Composite baseband

To combiner .4—

Video

Left audio

Composite baseband

Left

Stereo demodulator

aud o

4. e e

Descr mbler

• FM stereo modulator

o a)

5 • VIdeo plus

BTSC stereo 45MHZ modulator o' BTSC audio

Right audio

TV ITV modulator To combiner

(Continued from page 54)

encoding systems, although less expensive, do provide a simulation of stereo, but their outputs do not accurately resemble the stereo relation-ship provided by the programmer. It should be noted that the use of non-BTSC stereo encoding devices is illegal for off-air television broadcasters, but not for cable operators. What cable operators must do, therefore, is to make sure they know what components they really are purchasing.

System configurations BTSC stereo can be implemented in the cable

headend in several configurations for a variety of applications. These include: TV stereo only or simultaneous TV stereo/FM stereo generation, with or without local commercial insertion, and with subcarrier demodulators or the VideoCipher descrambler as the baseband audio source. To further complicate matters, configurations differ for part-time or full-time network scrambling. Four typical systems will be discussed here. (Reasons for retaining your FM stereo delivery will be discussed later in this article.)

Figure 2 is a diagram of a system generating both BTSC and FM stereo. A satellite receiver is used for the video source, while a subcarrier

demodulator provides left and right baseband audio. In this and in all other examples, the same baseband audio source drives both the FM and the BTSC modulators (the modulators typically will have high impedance inputs, eliminating loading problems). A descrambler easily can be substituted for the stereo demodulator in full-time scrambled systems to provide the baseband audio and video signals.

In Figure 3, the descrambler is used to sup-ply these signals. This system is identical to the one in Figure 2 except local commercial inser-tion also is utilized. A network cue (contact closure or DTMF) provides switching commands to the VCR controller to switch between network and commercial (advertising) program sources. During network operation, stereo audio is input to the BTSC and FM modulators directly from the descrambler, while video is routed through the

VCR controller. During commercial operation, the VCR containing taped commercial programming is switched on simultaneously with auxiliary audio inputs on both the BTSC and FM modulators by the VCR controller. Thus, commercial audio at the auxiliary inputs in switched in, while network audio is switched out, and commercials run on both the BTSC and FM systems. At the end of the commercial interval, a second network cue stopsthe commercial insertion process and the systems switch back to normal network operation.

Prior to beginning full-time scrambling, pro-grammers first implement a testing period dur-ing which the network is scrambled only part time. For networks that provide stereo audio sub-

ffl.1.1e111.•

I..

dirrO i < fl.• .... i 4

Remote Control/Tone Signaling Remote Control Systems

6002 6 Channel DTMF Control For Telephone Line 6003 6 Channel DTMF Control For 2 Or 4 Wire Line 6005 8 Channel DTMF With Timer And Alarm Autodial 5005 Central Control-Gather, Sort, Store, Display

Cue Tone Systems

3000R-105 Receiver, Up To 13 Codes, W/Telephone Access Rack Mount, (5 Codes) 984 Receiver, Up To 3 Codes, Wall Mount (2 Codes, Single Digit, Momentary) 3000R-103 Encoder, Up To 4 Codes, W/Verification, Rack Mount (2 Codes) 935 A Encoder, Two Multi-Digit On/Off Code Pairs, Wall Mount

Accessory Devices 3000P-9 Program Timer-18 Events, 4 Outputs 3000P-14 Audio/Video Relay Panel-4 Channels 3000R-14 Modular Commercial Insertion W/2 Channels, Decoders And Verification 3000R-72 Emergency Alert System-Dial-Up Access To 12 Balanced Lines 955-8 Remote Radio Control-Desk Telephone W/Audio Frequency PTT 937 B FCC Registered Unattended Telephone Answering Device

Printed Circuit Boards DIME Decoders • DTMF Encoders • Timers • Relay Cards • Power Supplies • Audio Detectors • Audio Generators • Audio Amplifiers • Audio Couplers • FCC Registered Answering Devices • Wall & Rack Mount Enclosures

Many Other Models and Options Available. Send for Free Literature.

M t, MONROE ELECTRONICS, INC.

E 100 Housel Ave., Lyndon,lle. NY 14098

i 716) 765-2254 • Telex 756662 • Easylmk 62547850

Rep. & Distributor Inquiries Invited


carriers prior to the implementation of scram-bling, additional complexity is added to the head-end puzzle.

Figure 4 is a block diagram of a combined BTSC and FM stereo configuration during part-time scrambling by the network. During scram-bling, video and audio baseband signals are pro-vided by the VideoCipher and the stereo sub-carriers are not transmitted over the satellite by the programmer. When scrambling ceases, however, the baseband signals no longer are pro-vided directly by the descrambler. The stereo subcarriers again are transmitted by the pro-grammer and a subcarrier demodulator is re-quired at the cable headend. Left and right audio is routed through the bypass audio inputs of the descrambler to its output terminals. Video is routed through the bypass video input from the satellite receiver to the descrambler output. When the network is transmitting unscrambled, the VideoCipher will not provide baseband audio or video outputs unless these signals are pro-vided at the bypass inputs from external sources

Although the configuration in Figure 5 appears complex, it is simply a compilation of the previous ones. For cable headends locally inserting com-mercials on networks scrambled part time, the commercial insertion process remains identical to that shown in Figure 3. Again, both the de-scrambler and subcarrier demodulator are re-quired to maintain stereo audio inputs to the BTSC and FM modulators. When the network switches between scrambling and non-scram-bled transmission, no disruption in the delivery of stereo audio to the subscriber will occur. When inserting commercials at the headend,

care must be taken in selecting the appropriate BTSC and FM modulators. While most cable systems insert commercials in monaural, the trend is moving in the direction of stereo. Not all modulators have commercial insertion interfaces and of those that do, some are monaural only, while others can process both monaural and stereo commercial audio. The caution here is to make sure you select the proper equipment for your present and future system requirements.

Interfacing to your TV modulator The primary installation issue not yet discussed

is interfacing the BTSC stereo generation system to your TV modulator. This interface is critical to successful implementation of BTSC. The way you interface will depend on the particular TV modulators you have, headend scrambling and other factors. There are four ways to interface this equipment. Three are considered the "stan-dard" interface methods and will be discussed here. The fourth method is at 41.25 MHz. The baseband audio interface is shown in

Figure 6.1n this case, the audio is encoded into the BTSC format and output to the audio inputs of the TV modulator. Baseband video is looped through the BTSC modulator to the TV modulator video input. When this interface is utilized, the TV modulator must be able to process the ex-tended bandwidth and deviation of the BTSC signal. Often, this means modifying the aural pro-cessing section of the TV modulator, either at the factory or in the field, or replacing it altogether with a BTSC-compatible unit. Also, the audio pre-

emphasis circuit in the TV modulator must be disabled, since 75 µS pre-emphasis already is provided in the BTSC encoding process. The adjustment of the audio modulation level

of the TV modulator is critical to stereo separa-tion. For example, a misadjustment of as little as 1 dB will limit theoretical maximum separation to 25 dB. Some BTSC modulator manufacturers provide a "calibration tone" feature to aid in set-ting the audio modulation level. This provides a rough setting and generally is designed to work accurately only with specific TV modulators The result may or may not be adequate stereo separation. If this interface is used, the setting of the audio modulation level of the TV modulator should be rechecked frequently. The preferred interface from the standpoint of

simplicity and hardware consideration is 4.5 MHz. There are two ways to provide a 4.5 MHz interface; the method selected will be determined by the inputs available on your TV modulator.

In Figure 7, both video and BTSC audio are combined and modulated onto a 4.5 MHz car-rier by the BTSC modulator. The resulting com-posite video signal then is input to the TV modulator. This is the easiest interface to make but has one drawback: Some TV modulators can produce interaction between the video and audio signals when the composite video inter-face is used. This interaction could be insignifi-cant or could result in buzz on the audio and/or video degradation. The degree of interaction, if any, is dependent on the particular TV modulator used and on signal injection levels. The way to eliminate potential signal interac-

tion is shown in Figure 8. In this example, BTSC audio is modulated at 4.5 MHz and output to the TV modulator. Baseband video is looped through the BTSC modulator and is input to the TV

modulator separately. This is the preferred method of interface from a technical point of view. Many TV modulators that do not have provisions for separate inputs can be modified easily and inexpensively in the field. With careful attention to levels, however, this modification may be unnecessary. One obvious advantage of interfacing at 4.5

MHz is that the aural section of the TV modulator is completely bypassed, meaning that no aural modification or TV modulator replacement is necessary. Another advantage is that no ad-justments other than input and output levels are required, and no periodic adjustments are need-ed. All critical deviation adjustments are factory set. If you decide to interface at 4.5 MHz, keep in mind that not all BTSC modulator manufac-turers offer this output. Of those who do, some provide a 4.5 MHz output as standard, others as options. The ability to combine video onto the 4.5 MHz carrier also may be an option or may be unavailable. Again, keep your system re-quirements in mind when selecting your head-end equipment.

Headend scramblers and alternative RF delivery systems

Over the past several months, Wegener Com-munications has conducted a series of tests to determine the mutual effects of BTSC stereo en-coding and headend scrambling. Numerical

Ten years ago we set some standards for our company...

• High Quality

• Competitive Prices

• Good Customer Service

Today... we're still using those same standards.

Corporate Headquarters

1023 State Street, Schenectady, NY 12301,

518-382-8000

5906 Breckridge Pkwy., Suite I. lampa. Fl. 33610, 813-623-1721

.'4630 Pacific hwy. East, Suite 8-7. rile, WA 98424, 206-922-9011

llighway 19. Old Socco Road. Cherokee, NC 28719. 704-497-5314

SEE US AT THE NATIONAL

BOOTH 1719


Figure 5: BTSC and FM stereo from a descrambler and subcarrier demodulator (part-time scrambling) with local commercial insertion

Satellite receiver

Composite baseband

Left audio

Video

Right audio

•

FM stereo modulator

FM

To combiner

Audio S— A

4— B

control

Composite baseband

Stereo demodulator

Left audio

Descrambler

Video

y BTSC stereo modulator

Audio

Video

Video plus 4.5 MHz or BTSC audio

TV modulator

TV

Right audio

• V

VCR controller

Control

Cue source

Audio

Video Control

To combiner

B Control

VCR

results of the testing will be presented in a paper at the 1987 NCTA convention, so several general comments will be made here. Scrambling systems from a number of manufacturers were evaluated. In all cases, some degradation in stereo separation occurred during the scram-bling process, but in no case did separation fail to meet or exceed levels comparable to off-air transmission. Nor did the BTSC process interfere with descrambler operation on the scramblers evaluated. Some problems did become evident, however.

With sine wave sync suppression scrambling, some audio components were evident in the video. The audio/video interaction was reduced to virtually imperceptible levels by interfacing to the TV modulator with 4.5 MHz BTSC audio and separate baseband video, as discussed previ-ously. This scrambling system had very little ef-fect on stereo separation. From an operational point of view, sine wave sync suppression scrambling is the most challenging, but with careful engineering it can work well with the BTSC stereo system.

Gated sync suppression scrambling caused no visible video degradation, but sync-buzz was evident in the audio. Further testing showed the buzz to be scrambling-related rather than BTSC-related. The noise effect was minimized by prop-er adjustment of the depth of video modulation, audio input levels and scrambler setup. The effects of FM trunking on BTSC stereo is

another area of concern to cable operators, and an evaluation of these systems is currently be-ing undertaken at Wegener Communications. At this time, some general statements can be made. First, no significant audio or video degradation has been found in subjective testing. Stereo

separation is affected, but again separation ex-ceeds that expected from off-air stereo at the subscriber system.

Several factors need to be taken into account when implementing BTSC over an FM trunk. Video deviation must be set correctly on the FM modulator. The FM demodulator output level and TV modulator video level adjustments will in-teract. Both must be set to the proper depth of video modulation to minimize sync-buzz and should be set a little below 100 percent. BTSC interfacing is, of course, at 4.5 MHz.

Microwave delivery systems can be configured in a variety of ways but, again, some general statements can be made. If possible, encode the stereo audio into BTSC and transmit the signal with video at 4.5 MHz over the microwave link. If the audio is to be delivered separately from the video, transmit separate left and right narrow-band subcarriers over the link. At the microwave receive site, demodulate the subcarriers into baseband left and right audio, then encode into BTSC. Either of these methods of transmission will result in a quality stereo signal. Transmitting encoded BTSC audio as a single multiplexed subcarrier apart from video, however, will likely produce increased noise and greater suscep-tibility to path fades, and is not a recommended method of transmission over the microwave link, especially in multiple hop systems.

Off-air television stations generally are pro-cessed at the cable headend by a heterodyne processor In most cases, the heterodyne pro-cessor will pass BTSC without modification. However, some older systems may require filter modifications to pass the extended bandwidth of the BTSC stereo signal. If you are not sure, check with the manufacturer.

BTSC signal quality and testing A high-quality BTSC encoder will deliver

separation in the 50 Hz to 14 kHz audio pass-band of about 32 to 45 dB, measured at the base-band audio output. A 4.5 MHz modulation will degrade the separation by no more than a few dB. Distortion of less than 1 percent, frequency response of +1 dB or better throughout a 50 Hz to 14 kHz audio range, and signal-to-noise greater than 60 dB all indicate a quality BTSC modulator. The encoder itself should cause no perceptible video degradation (remember, video is one of the inputs to the BTSC modulator). If the BTSC modulator is supplied with an auxiliary input for local commercial insertion, there should be no reduction in performance when this inter-face is used. Again, a stereo local commercial insertion interface is recommended.

In the BTSC encoding process, gain or phase tracking errors between the L +R and L-R sub-channels will cause rapid loss of separation. All adjustments to components on the BTSC modulator are precisely set by the manufacturer and no attempts should be made by the cable technician to alter these settings. The only ad-justments available to the cable system are left and right audio input level and, if needed, 4.5 MHz output level. (The output level is normally factory set and probably won't need readjustment.)

If the BTSC modulator is equipped with LED level meters for setting the input levels, no test equipment is needed. The 4.5 MHz output level can be verified with a spectrum analyzer, if desired. Rough separation measurements can be made with an oscilloscope. If precise measurements of BTSC operation are desired, quality test systems are available from several


manufacturers. (VVe use the Modulation Sciences Model SRD 1 and Belar BTSC reference monitor) A brief look at cable converters also is in order.

Generally, an RF converter will pass the BTSC signal intact without problem. Baseband systems can provide problems, however. Baseband con-verters that pass BTSC stereo typically will do so only with the volume control turned up. Many older baseband converters will not pass the en-tire BTSC signal without modification. Converter manufacturers are addressing potential prob-lems and offer various solutions to make their products compatible with BTSC. If you have questions about your system, contact the manufacturer

Subscriber issues BTSC stereo delivery provides one obvious ad-

vantage to the cable subscriber. With FM stereo delivery, the cable is split in the home and one splitter output is connected to the antenna input of an FM receiver. When changing television channels, the subscriber also must change the station the FM receiver is tuned to in order to receive stereo for the new TV channel. Although this is inconvenient, if the FM receiver and TV are located in different rooms, the subscriber like-ly won't take advantage of FM stereo at all. BTSC stereo, on the other hand, is transmitted along with video on the television channel. The stereo

audio tracks with video whenever the television channel is changed, and no splitters or signifi-cant additional wiring is required to install the stereo decoding equipment. Some cable subscribers will prefer to receive

FM stereo rather than investing in new BTSC stereo receiving equipment, however. The cable operator should consider delivering one or both stereo methods on each channel appropriate for subscribers' needs, especially if an FM delivery system is already in place on some of the cable channels. How does the subscriber receive BTSC stereo?

One way is to purchase a stereo television. Televi-sion manufacturers are now building stereo decoders into low-, mid- and high-end sets. Estimates indicate that more than half the new televisions sold in 1987 will be BTSC-capable and that they will cost little or no more than monaural versions.

Stereo televisions fall into three catagories. The true stereo television contains BTSC decoding circuitry, a stereo amplifier and stereo speakers, either attached or detachable. The "stereo-ready" television may contain a BTSC decoder but requires interface with external components such as an amplifier and/or speakers to complete the stereo system. More often, stereo-ready lys provide a wide-band baseband (multiplexed) BTSC or a 4.5 MHz output to interface with an external stereo decoder. Still other "stereo-capable" televisions will demodulate the 4.5 MHz carrier and output a multiplexed BTSC audio signal. An external adapter is required to decode this signal into left and right audio. The stereo adaptor is the second method of

BTSC stereo reception, and one that is relative-ly inexpensive. Generally, a stereo adaptor will accept the Channel 2,3 or 4 output from a cable converter (or the multiplexed audio output from

...thru the years, we stuck with these standards.

• High Quality



and ... we are proud to say, BRAD maintains its quality philosophy and has earned a reputation second to none in our industry.

Call: I -800-382-BRAD

In NY, Call: I -518-382-8000

Corporate Headquarters, 1023 State Street Schenectady, NY 12301, 518-382-8000

5906 Breckridge Pkwy., Suite 1, Tampa, Fl, 33610, 813-623-1721

4630 Pacific Hwy. East, Suite B-7 Fife, WA 98424, 206-922-9011

Highway 19, Old Socco Road, Cherokee, NC 28719, 704-497-5314

CLEARLY BETTER

SEE US AT THE NATIONAL - BOOTH 1719




r

E-Z TRENCH OUR NAME

SAYS IT ALL

cuts: 1-2" wide/7" deep

Can it pay for its self in only one day?! E-Z Trench makes trenching a very quick and easy one man operation, while saving valuable time and money. Cuts approximately 100 feet in five minutes. Giving the most professional look possible with vitually no damage to the turf. Its rugged construction and dual belt drive produces long and dependable service, with a very small investment.

J-2000 cuts: 23/4" wide/8" -131/2 " deep

Shouldn't you consider an E-Z Trench?

Call for: Nearest Distributor or order direct.

E-Z TRENCH Rt. 3 Box 78-B

Loris, S.C. 29569 808-756-6444

Ièr Reader Service Number 88.

Figure 6: Baseband audio interface

Video

Left audio

Right audio

Baseband video loop-thru

BTSC stereo modulator BTSC audio

owlBaseband TV modulator

RF output

Figure 7: 4.5 MHz composite video interface

Video

Left audio

Right audio BTSC stereo modulator

el4.5 MHz BTSC +video

TV modulator

RF output

Figure 8: 4.5 MHz BTSC and separate baseband video interface

Video

Left audio

Right audio

Baseband video loop-thru

BTSC stereo modulator

4.5 MHz BTSC audio 11?

TV modulator

RF output

a stereo-capable television), decode the BTSC stereo into left and right audio, and output the video channel to the television. Some adaptors include a stereo amplifier and speaker connec-tions, while others interface with the auxiliary in-put of an external amplifier. As well, some include a variable RF tuner for off-air BTSC reception.

Essentially, the BTSC stereo adaptor will turn an existing monaural television into a stereo television—the difference being that the decoder is external rather than internal. Separation and other performance specifications will vary from good to poor and care in selection is therefore important. The same can be said, of course, for stereo televisions. A third method of decoding BTSC is with a

stereo VCR. The VCR must contain a BTSC decoder to operate with the stereo system. As with adaptors and stereo televisions, BTSC decoders in VCRs vary in quality.

Installing the subscriber BTSC system is sim-ple and can be accomplished easily by most subscribers. However, a subscriber may call the local cable system for assistance. It is to your ad-vantage to provide this help; however, keep in mind that the BTSC system usually is subscriber-owned. You may want to charge for house calls. BTSC and FM stereo performance at the sub-

scriber drop are generally equivalent. BTSC con-venience to the subscriber is superior to FM. In

regards to performance, however, if subscribers accept the quality of FM stereo, they will certain-ly be pleased with the quality of BTSC.

Opportunity knocks The BTSC stereo delivery system now is used

by over 1,000 off-air television stations. Subscribers are purchasing systems to receive BTSC stereo, creating an opportunity for cable systems to provide an important new service to their subscribers and to increase penetration on channels delivered in stereo. This means add-ed revenue to the cable system.

At some point, most cable systems will take a hard look at providing BTSC stereo, and many will decide to implement BTSC on several chan-nels. It is to your advantage to understand BTSC stereo technology, the short- and long-term capabilities needed in your particular system, and the equipment available to satisfy your specific requirements. As well, it is to your ad-vantage to share your knowledge with your subscribers, encouraging them to add BTSC stereo in their homes. Although the BTSC system is complex, the

critical factors are taken care of by the major en-coder manufacturers. What remains is a straightforward delivery system that, with proper engineering at the cable system, can be installed and maintained easily. L.-1

74 MAY 1 987 COMMUNICATIONS TECHNOLOGY

For the next ten years, our standards will remain the same...

• High Quality



While keeping up with the rapid changes in technology, and growing to better service your needs... we will never lower our quality standards or the emphasis on serving you, our valued customer.

So thank you for helping BRAD become the largest independ-ent sales and service facility of its kind. We look forward to another challenging decade.

Call: 1-800-382-BRAD In NY, Call: 1-518-382-8000

CLEARLY BETTER

Corporate Headquarters, 1023 State Street, Schenectady, NY 12301, 518-382-8000

5906 Breckridge Pkwy., Suite I, Tampa, 11. 33610, 813-623-1721

4630 Pacific Hwy. East, Suite B-7, life, WA 98424, 206-922-9011

Highway 19, Old Socco Road, Cherokee, NC 28719, 704-497-5314

SEE US AT THE NATIONAL - BOOTH 1719


Transportation of stereo signals over FMLs By Luis A. Rovira Senior Engineer. Broadband Communications Division Scientific-Atlanta Inc

Amplitude-modulated links (AMLs) and frequency-modulated links (FMLs) are used routinely in CATV systems to transport signals between hubs, satellite receiving stations and headends. When used properly this equipment is nearly transparent to video and audio signals. Care should be taken, however, when adapting existing systems to carry BTSC stereo. FM Ls in particular can cause significant degradation of the stereo signal if improperly used.

Typically, the FM transmission systems used in CATV frequency-modulate one VHF carrier with video information and a separate VHF car-rier with audio information. In upgrading such a system all that is necessary is to add one more carrier for a second audio channel. One carrier then is assigned to the left audio channel and the second to the right. Encoding of the audio into the BTSC format can be done after the link, with the encoder and modulator co-located. All the performance specified for the FM link is preserved.

In systems that are near or at capacity it is tempting to avoid adding the extra channels.

Some stereo encoders have built-in 4.5 MHz sub-carrier modulators and provide a video plus audio subcarrier at their outputs. It would seem a simple matter to connect such an output direct-ly to the video input of the FM link and avoid the separate audio channels altogether. Unfortunate-ly the results could be quite marginal.

Video clamps In sending video over FM links some sort of

DC restoration may be used to avoid field-time distortions. Video clamps normally act to restore the sync tips to a constant DC voltage. Although all clamp circuits use active components, some are more "active" than others. These circuits detect the presence of the sync and then trig-ger active devices to saturate and clamp the signal path to some stiffly held voltage. Unfor-tunately, any subcarrier present in the signal also is effectively "shorted" to this voltage for the dura-tion of the clamping period. This produces an amplitude modulation of the subcarrier at the horizontal frequency (f H) that can approach 100 percent. Any subsequent AM-to-FM conversion in the

signal path or the consumers' receivers will then cause a discrete carrier at fF., that will add vec-

REBUILDING OR UPGRADING YOUR CATV SYSTEM?

WANT TO AVOID THE USUAL STRESS?

NACOM's YOUR ANSWER!

We offer experienced personnel, competitive pricing, completion on schedule, nationwide service and turnkey if desired. CALL

Jerry Evans NaCom Construction Corp. for Plant Construction and Engineering or

Eli McKay NaCom Corp. for Drop Replacements/transfers/installs/MDU wirings/ traps/converter change-outs

at 1-800-848-3998 or 1-614/895-1313 Available with Regional Service Centers in Arizona, Southern and Northern California, Georgia, Kentucky, Minnesota, Missouri, Ohio, Texas and Virginia. Local service centers in many other locations.



tonally to the existing pilot. The resultant pilot will have a phase that is different from the phase of the original pilot. This phase error will cause the synchronous subcarrier detector to add a phase error to the recovered difference signal and thus seriously degrade stereo separation. Buzz also can be added to the audio due to inadequate AM rejection in the receiver's FM demodulator.

Bandwidth considerations Because the video channels normally are in-

tended to carry only video, frequency response usually is specified only to 4.2 MHz. Though not necessarily present, the user should beware of sharp low-pass filters or transmission zeros in the signal path at frequencies above 4.2 MHz. Before combining video with a 4.5 MHz subcarrier in any system, low-pass filtering of the video may be required to prevent spectral overflow of the video from interfering with the audio carrier. A less obvious problem is that of overmodula-

tion. FM links normally have bandpass filters at the output of the transmitter in order to protect adjacent channels. Selectivity also is provided in the receivers in order to reject adjacent chan-nels. The bandwidth of these filters, along with the linear deviation range of voltage-controlled oscillators (VC0s), normally limit the deviation of the video carrier. With this upper limit in mind, manufacturers usually deviate as much as possi-ble to preserve video signal-to-noise ratio.

If a user then adds a subcarrier to the video signal without reducing the modulation sensitivity of the VCO, two things happen: Deviation is in-creased by the added peak voltage of the video plus subcarrier (usually .1 V p-p), and the highest modulating frequency increases from 4.2 MHz to about 4.6 MHz (stereo plus SAP). The resulting increase in bandwidth can exceed the band-width of the channel resulting in increased distor-tion of the audio and video.

Signal-to-noise ratio The transmission of video plus audio subcar-

riers as a frequency-modulated carrier is not without precedent in the CATV signal chain. Satellite delivery of signals normally is done this way, so much already is known about the technical tradeoffs involved. Early on it was discovered that a better signal-to-noise ratio (S/N) could be obtained by using multiple audio sub-carriers as opposed to one multiplexed subcar-rier. The same consideration applies to an FM video plus multiplexed subcarrier signal.

It cannot be denied that it is possible to transmit BTSC stereo as a 4.5 MHz subcarrier added to video over an FM link. By disabling active clamps, checking frequency response, filtering any spectral overflow and reducing deviation the BTSC signal should survive, though bruised with a marginal S/N. The problem is that the FM link is only a small part of a complex distribution system, of which no single component should be so marginal. By contrast, transmission of separate left and right audio information over in-dividual channels of an FM link is an excellent way to transport stereo and entirely avoid any degradation attributed to the FM link. ffl

MOST FOLLOW STANDARDS...

In every industry there are leaders who are innovative and dedicated to pro-ducing the highest quality product. The vision of these leaders fuels progress; they forge ahead and bring new solutions to the marketplace. Most of all, these leaders listen to their customers and trans-late their needs into products and services of the highest standard.

In CATV, Alpha has set the standard in Standby Power technology. This leadership is based on a long list of ̀firsts' in powering concepts and product capabil-ities. Implementation

...A VERY FEW SET THEM.

of Alpha's single ferro-resonant power supply design revolu-tionized the industry and gave new meaning to cable system reliability and customer satisfaction.

Direct cost re-ductions through improved battery performance and

simplified system maintenance were brought about by Alpha's temperature compensating and performance monitor-


ing circuit designs. In addition to these technological contri-butions, Alpha has

established the highest quality and safety standards. To date Alpha remains the only Standby Power manufacturer offering UL, CSA and SEV listed products to the CATV industry. The unique Lifeline

status monitoring system provides

diagnostic informa-tion and remote control facilities on one-way and two-way cable systems. This pioneering develop-ment now enables operators to optimize service strategies and reduce overall system maintenance costs. Lifeline is Alpha's latest in a series of

historic status monitoring mile-stones: the first and only stand-alone power-supply moni-toring system, hardware interfaces

for the major ampli-fier monitoring systems, and complete monitoring software have all preceded the Lifeline introduction. Alpha Technologies

set the standards in Standby Power for one reason: Alpha's customers won't settle for second best.

17 in ALPHAI ITECHNOLOGIES

.re Here to BackYou Up. 3767 Alpha Way Bellingham, WA 98225 TELEPHONE. 206-647-2360

7033 Antrim Ave. Burnaby. B C V5J 4M5

TELEPHONE: 604-430-1476 TELEX: 04-356760


I q86 Alpha Technologies

Leakage A multifaceted problem Although this article originally was presented at the Society of Cable Televi-sion Engineers' 1977 reliability conference, much of the content and many of the concerns offered are as real today as they were 10 years ago. Bob Dickinson is currently president of Dovetail Systems Corp.

By Robert V.C. Dickinson

The subject of CATV leakage is timely for examination at this reliability conference. In the CATV business we operate our "closed systems" in an environment where the number and magnitude of external RF sources is constantly increasing. This represents an increasing threat to high-quality CATV system operation. In addition, we are being challenged by over-the-air users of the same spectrum with the charge that we are not operating "closed systems" but that we are leaking and the power radiated may be detrimental to those services. We will examine the situation in a broad manner, focus on some current major problems, and look at ways in which we can improve our system integrity and thereby promote higher CATV quality while reducing any threat to other parallel services. The cable industry has been in existence for over 25 years and has grown

from rather rudimentary beginnings to an industry representing over 3,500 systems and perhaps 14 million subscribers. Review of the beginnings of the industry would indicate various approaches to controlled TV transmis-sion including crude but effective technical implementations. Open wire systems have brought TV to some where there was no other way. A lot of braided shield trunk cable has been employed. Many thousands of pressure taps have dotted the scene for years and are still in existence in many systems. As the industry developed it became clear that cable systems that allowed outside radio frequency energy to leak in had potential major problems. The intermodulation distortions (beats and cross mod) were known and controllable factors; however, a CB transmitter operated close to the leaky system could degrade or obliterate the signal on several channels in large portions of the cable system. Since the CB population has grown with leaps and bounds, this problem continues to increase rather than decrease.

For protection of other services the FCC, as part of 76.605 on technical standards, contributed rules governing permissible system radiation and required its measurement (76.601 & 76.609[h]) on an annual basis. This requirement turned out to be a very technical, rigorous one, which, if univer-sally adhered to, would reduce system radiation to a very low level in most cases. The full force of this regulation was restrained by the infrequent measurements required so that its full impact has not been fully felt by most. The testing requirement, once per year, is normally implemented by measuring three arbitrary points. If these three points pass, well and good. If one or more show excessive leakage it is repaired and the test repeated. The data is recorded for "public inspection" and the whole matter is forgotten for one year and the remainder of the system goes untested and unrepaired. The result has been less than universal recognition and control of system egress and ingress. Many people in the industry, however, have seen beyond the simple

requirement of taking the required data once per year. It has been ap-parent to some that sooner or later this regulation will be seriously enforc-ed. Probably more important, leakage out of a system, which would lead to violation of this regulation, invites ingress and results in service calls, dissatisfied customers, and all that goes with it. As a result various techni-ques have been developed and are in use for more comprehensive leakage checking.

Early in the game leakage was monitored by listening for signals in the FM band. A signal on a non-off-the-air frequency was monitored in the service vehicles using a standard FM receiver tuned to the prescribed frequency. Detection of this signal obviously indicated leakage from the cable system. Experience as to location of responses, signal level and the like provided a way of monitoring systems during routine travel

throughout the system. The results were improved preventive maintenance and subsequent reduction of ingress. The location of many illegal hookups made up for some of the effort expended in keeping a "tighter" system.

Mid-State Electronics now markets their Cuckoo device, which produces a signal in the FM band. The signal level may be stepped and the modula-tion may be warbled for identification. By noting how may steps can be heard at a given location an estimate of the leakage intensity can be made. Another device along these lines is manufactured by ComSonics and

is called The Sniffer. Rather than a wide-band FM signal, a narrow-band AM signal is used with a peculiar, identifiable modulation. The Sniffer has a fixed-tuned receiver and employs a probe-type head rather than a stan-dard FM receiving antenna. The receiver sensitivity can be varied. When the signal is heard the leak may be located by probing with the head and constantly reducing the sensitivity until the exact point of leakage is located. Similar equipment is in wide use in Canada. The onset of concern for more serious monitoring has shown that stan-

dard cable connectors may be tight when they are installed but may develop leakage over a period of time. This effect is caused by deforma-tion of the outer shield within the connector reducing the area of contact and hence the integrity. Manufacturers over the past several years have developed an "RFI" connector that is designed to prevent this deforma-tion and maintain connector integrity. The main principle of these con-nectors is the insertion of a mandrill (often stainless steel) under the end of the cable sheath where it is clamped within the connector. This prevents deformation and maintains contact. Other improvements are included in connectors by various manufacturers but the basic long-term stability and integrity of the connectors have been greatly improved.

Concerns begin to grow As early as 1971 the Federal Aviation Administration became concerned

that the growing CATV industry might become a source of radiation that could interfere with aircraft navigation and community services. This was a serious concern since it deals with "safety of life" and enormous finan-cial investments, commitments and liabilities. The Office of Telecommunica-tions Policy, U.S. Department of Commerce, through the Institute of Telecommunications Sciences at Boulder, Colo., has issued four studies relating to this field. Two of these were sponsored by the Department of Commerce and two by the Federal Aviation Administration. The titles are as follows:

OT 74-39—Electromagnetic Compatibility of Simulated CATV Signals and Aircraft Navigation Receivers (USDC) OT 75-73—Radiating Aerial Coaxial Cable Measurements (FAA) OT 75-75—Flight Tests Measuring Compatibility of Simulated CATV and

VOR Signals (FAA) OT 75-192—Electromagnetic Fields ola Dielectric Coated Coaxial Cable

with an Interrupted Shield (USDC)

The titles indicate much of the content of the investigations. These studies were concerned largely with possible interference to navigation aids rather than voice communication channels. The results, summarized in a few words, are that CATV systems can leak, particularly under conditions of catastrophic failure (broken or badly damaged cables in high-level cir-cuits) in a manner that can cause malfunction of aircraft navigational ser-vices. The conditions that are required to cause such interference demand very precise control of frequencies specifically related to the navigational aids in question. When these rumblings were received by the industry more study was

undertaken and numerous cable operators made the decision to avoid the use of frequencies where interference might be caused. With the limited knowledge available the likelihood of interference seemed to be very small; however, should there be an aircraft accident in the vicinity of a cable system


tereo outline:

Just call the Hotline. The technical assistance you need to implement the latest stereo technology is at Wegener Communications.

At Wegener, we've done our homework again—researching and testing every possible combination of cable headend products with our Model 1791 Broadcast Stereo Encoder.

Scrambling systems, microwave, supertrunk— our technical experts want to share the results of the tests with you. Because at Wegener, the sale is not complete

until you're satisfied with the performance of the equipment.

Let Wegener help analyze your system and determine exactly what you need to add true broadcast stereo sound.

1-800-445431SC Call the Wegener Stereo Hotline and receive your copy of our latest Stereo Applications Report. UV WEGENER COMMUNICATIONS

TECHNOLOGY PARKiJOHNS CREEK 11350 TECHNOLOGY CIRCLE DULUTH, GEORGIA 30136

(404) 623-0096 TELEX 54-3634 FAX (404) 623-0698



carrying signals in the navigation spectrum the political ramifications could be disastrous. Lawsuits might result and the burden of the proof could well be upon some cable operator rather than on the FAA or FCC.

For these reasons many operators abandoned the use of Channels A-1 and A-2, which were sometimes employed for special services. The fre-quency range from 108 to 136 MHz includes Channels A-2, A-1, A, B and part of C; however, only the frequencies from 108 to 118 MHz contain the navigation aids that were the major area of concern. The frequencies from 118 to 136 MHz carry aircraft communications channels. In any event many people were becoming concerned about this possible problem. Those in the FAA were interested in shutting off any possible interference and many in the cable industry were trying to determine ways of eliminating any possible interference even if leakage were to occur.

The Harrisburg incident Early in April 1976 an episode began that was apparently "the straw

that broke the camel's back." In Harrisburg, Pa., a rather large (over 30,000 subscribers) and an older system (built around 1966 with pressure taps throughout) became the goat for the industry. The story goes this way. The FAA assigned a new approach control frequency for the area. The frequency chosen was 118.25 MHz. As soon as this frequency was com-missioned, pilots began to complain that there were whistles on the channel showing up between transmissions. These whistles were quite annoying. The FAA began to search for the problem and spent some time without success. The FAA then called in the local FCC field bureau, which also started looking. Eventually the local cable company was called. It admit-ted using a 118.25 MHz pilot carrier, but stated correctly tnat the pilot had no modulation. For this reason it was overlooked for some time until in desperation the FCC asked that the CATV pilot be turned off. The in-terference vanished with the pilot.

Further investigation showed that there were four sections in the system each operating an independent 118.25 MHz pilot. Since these pilots were not from a common source their frequencies, although crystal-controlled. were somewhat different. The reception of two or more by an aircraft

receiver produced audio beats. These beats had been erroneously at-tributed to modulation on a single source. With the discovery that it was cable system leakage causing the difficulty the cable company immediately removed the pilots. The AGC amplifiers ran wide open for a few days while they were reconfigured to operate on Channel 5 visual carrier. The prob-Iem was solved in this manner and the cable system continued to leak without any other known problem. This particular system is now being rebuilt; however, it is a large one and will take some time to accomplish. The discovery of this situation was all that was needed to swing the FAA

into action to lobby for elimination of CATV usage of frequencies parallel to "safety of life services." These frequencies included the 108 to 118 MHz navigational aids band; 118 to 136 MHz aircraft communications band; 121.5 MHz, an aircraft emergency frequency; the 156.8 MHz marine emergency frequency; 243.0 MHz (second harmonic of 121.5), another aircraft emergency frequency; and the band 225 to 400 MHz for aircraft navigation and communications frequencies covering many commercial and military usages. Heavy pressure began to be exerted in this area resulting in high-level government requesting that the FCC remove all of these frequencies from the cable CATV spectrum. A summation of the results of such a move indicates that there would be only 19 channels that could be used for CATV carriage. Obviously the impact of such a ruling would be a disaster for the CATV industry.

Looking for the solution As these pressures were building, various elements of the industry, coor-

dinated by Delmer Ports of the National Cable Television Association, began to plan their strategy. Industry representatives continued liaison with the FCC, FAA, Office of Telecommunications Policy and others to come to some sort of a reasonable solution for this problem. As these informal discus-sions proceeded the FCC felt obliged to issue a notice of proposed rule making (Docket 21006) putting forth the various alternatives available to control the situation. The Interference Subcommittee of the NCTA Engineer-ing Advisory Committee under the leadership of Frank Bias of Tele-Vue Systems, has spent much time in preparing comments for the notice of

Communicate with us! Microllect ut krs the 1m 1st comprehensive line of guyed and self-supporting towers passive repeaters. and waveguide support systems in the communications industry. Send for your free copy of our capabilities brochure today

IMICROFLECT

ENGINEER-Broadband, Communications

and Electronics System Michigan State University has an advanced level opening for a seasoned, operations-oriented communications engineer. This position requires the applica-tion of extensive and diversified engineering principles and methods to the opera-tional development of a large broadband LAN and various electronic systems.

Examples of typical tasks are the following. Plan, develop and coordinate large and vital broadband cable and electronic systems as well as smaller complex projects. Develop preventative maintenance programs for broadband television and data networks, and other electronic systems. Design broadband cable trunks and distribution systems. Consult on maintenance and troubleshooting problems for broadband cable, general analog, digital and radio frequency communica-tion systems. Assist with the development of improved and innovative operational procedures for high technology systems in a university environment. Develop, direct and implement technical training of personnel. Applicants must have a BSEE and reasonable progressive and responsible experience in planning/designing broadband and other electronic systems, installations and equipment. Some supervisory experience is also required. Registration as a PE in the State of Michigan is desired.

Contact Michigan State University Employment Office, 110 Nisbet Building, 1407 S. Harrison Road, East Lansing, MI 48824. Refer to Position A654.

MSU is an Affirmative Action/Equal Opportunity Institution. 35 7.5 25th St. SE • PA). Box 12985

Salem, OR 9-309-098S 15031 363-926- • ri.x S10-599-010-


How to buy, sell and repair converters.

NI anaging your converter inven-tories for profit may require turning old converters to cash,

purchasing new and used equiptent as well as repairing existing inventories.

All makes, all models.

Where do you look for the buyers and sellers of each converter make and model? Service reps at PTS/Katek talk to more system managers everyday about converter

needs than anyone in the business. PTS/ Katek buys all makes, all models and sells only to authorized cable systems. If it's not in stock, PTS/Katek knows where to find it.

New Jerrold equipment in stock Many distributors only want your big orders and work from manufacturers' inventories. PTSŒatek has one of the largest private inventories. Plus they ship every in stock order, large or small, within 24 hours.

All repair is not the same. Your repair company should work closely with manufacturers. This assures trained technicians with factory support. Consider parts availability, turn-around, warranty, and quality in addition to price. It's important to know the company you ship your converters to will be in business tomorrow.

Writing the book on addressable repair.

New chapters are being written on ad-dressable repair every month. One com-

pany has consist-ently been the EMI

leader in this area. PTS/Katek repairs more addressable than all repair companies combined.

Do it yourself. If you have an existing in house repair program, you'll find it economical to sub-contract sophisticated repair such as tuners, RF, IF, and decoder mod-

ules. Talk to PTS/Katek.

Call toll free today. Talk to the converter specialists. If you want to know more about buying, selling or re-pairing converters call 1-800-441-1334.

DTC al - The Converter Specialists

Bloomington, IN Arvada, CO Detroit, MI Indianapolis, IN Jacksonville, FL Jupiter, FL Longview, TX (800) 441-1334 (303) 423-7080 (313) 862-1783 (317) 353-6668 (904) 389-9952 (305) 747-1808 (214) 753-4334

Newbury Park, CA Norfolk, VA North Highlands, CA Pittsburgh, PA Westfield, MA Yeadon, PA (805) 499-8702 (804) 853-5844 (916) 334-2012 (412) 787-3888 (413) 562-5205 (215) 622-0450



proposed rule making. Since this notice was issued in late November a number of meetings have been held and hundreds of hours (not to men-tion thousands of dollars of transcontinental airline fares) have been spent by committee members preparing comments. Comments were original-ly due on Jan. 17, 1977, but at the request of NCTA and others, has been postponed until March 3, 1977. The notice of proposed rule making ad-dressed two questions:

1) How can it be assured that cable television systems operating on fre-quencies used by air navigation systems and aeronautical and marine emergency radio services do not cause harmful interference to those safety-of-life services?

2) What frequency channeling plan or plans should be used by cable television systems for equipment compatibility, for prevention of interference to over-the-air services, and for other purposes? The NCTA response focuses on question #1. Some of the proposals

presented by NCTA will have impact on question #2. The position has been taken that a general frequency plan cannot be established at this time and that only those frequency provisions affecting question #1 should be considered in this rule making. The scope of the FCC's proposal is summarized in its paragraph 1.3

as follows: "a) To adopt a frequency channeling plan for the delivery of television

signals to cable television subscribers. This frequency channeling plan may include the so-called mid-band and super-band channels as well as the standard television broadcast channels. Alternatively the channeling plan may prohibit operation in whole or in part on the frequency band used for navigation and safety purposes.

"b) To require the use of the proposed frequency channeling plan for all Class 1 and Class 2 cable television channels and for some Class 3 and Class 4 channels as well.

"c) To adopt standard designations for those channels not used in over-the-air service.

"d) To modify our requirement for monitoring cable television systems for possible signal leakage.

"e) To adopt rules specifying the conditions under which a cable televi-sion system that is found to be causing harmful interference to authorized radio services may be required to cease operation and specify the condi-tions under which operation may be resumed.

"f) To adopt restrictions on cable carriage and signals within certain air traffic control and safety services bands." The docket goes on to discuss these various areas. A number of possi-

ble avenues of action are outlined including frequency offsets and power restrictions in lieu of vacating the frequencies. Increased monitoring and perhaps revisions of allowable leakage levels are mentioned as well as institution of a system providing for partial or total cable system shutdown if interference is detected. Some of the measures proposed would be very difficult for the cable

industry. NCTA takes the position that certain protective measures are in order but that they need not nearly be as stringent as the FCC has pro-posed. Before looking at possible responses to Docket 21006, let us look at the actual problems involved.

The interference problems The navigation aids in question are the VOR and instrument landing

systems. The VOR (VHF Omni-Range) is a system whereby aircrafts can select a radial to or from the navigation aid station and fly that radial by centering an indicator pointer. Technically the system utilizes a carrier fre-quency onto which is amplitude modulated a 9,960 Hz subcarrier. The subcarrier in turn is frequency modulated ±480 Hz with a 30 Hz reference signal. The entire transmitting antenna is mechanically or electrically rotated at the 30 Hz reference frequency to produce a spatial modulation of the entire signal. The aircraft receiver detects the 30 Hz reference on the FM subcarrier and compares it with the 30 Hz spatial amplitude modulation and determines the bearing of the aircraft relative to the station by the phase difference between the two signals.

In order to cause harmful interference a relatively strong signal must be located within 2 or 3 Hz of either 30 Hz sideband. Virtually phase-lock conditions must be maintained to cause an offset error. The general case

TV STEREO

Learning Industries MTS-2 BTSC Stereo Generator, with dbx® companding, provides cable systems with a means to transmit BTSC stereo TV audio.

FEATURES INCLUDE:

• Dual Stereo Inputs., for Local Ad • Level Controls accessible from front Insertion or Back-up Audio panel

• Stereo Synthesizer Built-in

• Separate Video and 4.5 MHz Loop-throughs

• Deviation Test Tone Built-in

• Self-contained, rack-mount unit, only 1.75 inches high

• Optional Audio Processing (Automatic Gain Control)

See us at the NCTA Show, Booth 3121/3122. •

180 McCormick Avenue Costa Mesa, CA 92626

(714) 979-4511 TWX: 510 600 4362



YOUR SYSTE IN BLACK &WHITE

The Window Field Strength Meter just became a serious and powerful partner in your system management. Introducing the new WINDOW SYSTEM MANAGEMENT PACKAGE.

This new package gives your WINDOW three powerful new features: expanded memory, real-time clock for memory reporting and a print

feature. Real-Time Clock: Now an internal

clock/calendar can be set which will time and date stamp each of the Memory screens. This gives you pin-point accuracy in determining when the operator was at a particular location in the system. Expanded Memory: Now you

can have up to 35 "snapshots" taken of screen readings throughout the system. They're stored in an easy to use Memory Library which can easily be reviewed later. You can view the actual data your tech saw in the field.

Printer Interface: Now you are no longer limited to screen recall alone. Hard copy is now available on any or all memory bins. Now it's easy to build a performance trail from any location in your system backed up in black and white! The new Bar Graph Printout displays Video or Audio

levels similar to the WINDOW'S standard Sweep mode display, including a summary listing of pilots and special channels. The Chart Printout provides you with a tabular listing of frequency and level measurements of all carriers in the entire system. With the new WINDOW System Management Package you no

longer have to guess what's going on in your system . . . you know.

ComSomes AN EMPLOYEE OWNED CORPORATION

CALL TOLL FREE 1-800-336-9681, IN VIRGINIA CALL COLLECT (703) 434-5965



of a high-level signal less than 3 Hz from these sidebands will produce a swinging indication of the pointer or loss of flag so that the pilot would know that a problem was present and disregard the resulting navigational information. Calculations of possible CATV leakage and its effect upon VOR circuits indicate that the probability of interference even under con-ditions of catastrophic leaks is very small. The instrument landing system (ILS) is composed of two parts. The

localizer tells the pilot which side of the flight path he is on in a horizontal plane and the glide slope gives the same information in the vertical plane. The glide slope system provides a path at a fairly low angle (in the vicinity of 2.5° above horizontal) to the landing point on the runway. The localizer signal is in the range of 108.1 and 111.9 MHz. This signal

is amplitude modulated at 150 Hz on the right side of the runway and 90 Hz on the left side. On course is the vertical plane indicated by equally detected modulation between the two sides. Locahzer course width is about 5° for full indication left to right. This represents a span of approximately 5,300 feet at a distance of 10 nautical miles from the transmitter. The glide scope is very similar to the localizer except that it operates in the frequen-cy range of 328.6 to 336.4 MHz. On the upper pattern lobe 90 Hz modula-tion is used and 150 Hz on the lower. The glide slope path is only about 1° wide or 1,060 feet at 10 nautical miles. The width of this path at touchdown is only a few feet, hence is a very effective guidance system. Both localizer and glide slope indications are usually portrayed on a "cross pointer" in-dicator. The pilot flies both indications to center both pointers in the inner circle of the indicator.

Interference with the localizer or ILS system requires the same type of frequency stability and precision as the VOR with the inferfering frequen-cy located approximately at the frequency of the modulation sideband(s). Here again the figures show that the possibility of interference by CATV leakage although not zero, is very, very small.

Interference with the communications channels, as in Harrisburg, is a somewhat different story. Interference to communications circuits generally requires a considerably higher signal level; however, any frequency within the received bandwidth of the AM communications receiver will be ac-

cepted and can be a source of interference. When the levels are very low, the squelch on the aircraft receiver will not trip hence the radiation will go unnoticed. If the signal levels are higher, the squelch will be tripped and assuming only one unmodulated signal exists, the only effect will be to cause a hiss or rushing sound rather than dead silence, as when there is no transmission being received. Signals of this level will be overridden by the communications signal from the higher power air traffic control (ATC) transmitter and will not be heard. It is difficult to configure an interference situation where the leakage from a cable system, even at maximum power level, can override the power from the ATC transmitter. The only case where this might happen is at great distances from the ATC transmitter and very close to the cable system. In this event the duration of such interference to a passing airplane would be quite brief. The FAA has built in restric-tions, such as "minimum enroute altitudes," which do much toward avoiding this situation. There are a number of other considerations that bear upon the whole

subject. For instance, over the past 25 years of CATV operation the Har-risburg incident has been the only reported complaint of interference to any of the aircraft navigation or communications services from CATV sources. Over the same period of time there has been an excess of 6,000 complaints from other radiating sources. Other radiating sources include millions upon millions of FM and TV receivers governed by Part 15 of the FCC regulations, which allows 28 dB more signal leakage at these fre-quencies than the current FCC cable leakage spec. Harmonics and spurious outputs from AM, FM and TV broadcast transmitters are a major potential source of interference and result in certain local frequencies be-ing unusable for air navigation and communications services.

The NCTA responds With all of the preceding in mind, certain conclusions have been reached

and five major points are being used as the basis of the NCTA comments on the proposed rule making. They are as follows:

1) Each cable system will maintain at its operating office a list of carrier frequencies currently in use on the cable system. This will facilitate loca-

It's 2 a.m. Do you know

where your database is?

1,,11.1 066 '•

.,11 113.57 1 1 16 61 U. 10.111 44460 per mon11. 6•5• I r.y , 19..4 ryorr.././1, fnete. (6.1.1166

Plain Text

. I*.,.' I, lo 61 19 61.111

Encrypted Text

Jones Futurex DES Encryptor - products provide

• Secure Data Base • Secure Communication Links

for the IBM PC or PC compatible devices

JONES FUTUREL, 3079 Kilgore Road Rancho Cordova, CA 95670 800-251-5111 in California 800-251-5112 elsewhere

*)",?*******( 1 FOR SALE

* SPECIAL LOW LOW RATES * Regular Special Prices Low Prices

CONVERTERS M-35 20,80 15.00 *

RSX 12,50 10.00 SX 1-0,90 8.00

Gammets 8,08 * 6.00 JRX 1.66 12.00 * JERROLD TRUNK AMPS

JN 300 MHZ All With Housings.

Regular Special * STATIONS Prices Low Prices

1# AGC Trunk w/dist. 3.50-0 315.00 * 2# MGC Trunk w/dist. 31-9,00 270.00 3# AGC Trunk only 290700 245.00 * 4# MGC Trunk only 230700 cx).(x) 5# High Gain dist. 349701 270.00 A Taps - 300 MHZ, FFT, EFT RMS ..$2r5er $2.50 ),.(

"VOLUME DISCOUNTS AVAILABLE" * All equipment is in workable condition. Don't miss out on these

super low prices.

* A 7 AMERICAN CA BLESYSTEMS OF FLORIDA 141 N.W. 16th ST.

Pompano Beach, FL 33061 (305) 946-0099

Contact: Kurt Kerrigan

********** Reader Service Number 62.


SCIE Over 3300 Cable Technicians and Engineers

Across the Country Have Enriched Their Knowledge of CATV Technology

As SCTE National Members.

Here's How:

SCTE Chapters

And Meeting Groups

the FTE7 INTERVAL A Guide to SCTE Chapter Development By John T. Kurgonalo Engmere V.. h, t. near. en

tel hut ruher MIT! rules ,uu mum h.1 It. to le tvr air a. • chapter dd ."1"1.

it.., Future hurter •. urne upt end gggggg tutu I hat ,AN.0 en. are du. te reel ... • lute ,er, *ell for the emu.

Md.. Auer., en off...el that au rholveu thepter.A IV. tIlt t able Teleu t'eud I,

SPECIAL ISSUE Why Do It? sum. ct there lurk, We get ten. s'

d I Ow ca.. the.. tuluor•leemtn.re •nd the hke mod dour fello. 'owe ter hnutan• •nd other. meter get g. t.. three teeming ...eau

ca. go to the nuuntun then leA • to ke the rnountaen

klehanuned The ,dule pup.. 1.4 SCTE ...prude were. tram, h. ata mender. Enfortunawle for *hat ever reason • kg or tr.,. ran t or

P.P. to two or three day noun, IN..• there... kw Ow local

Red tletr pertole in tree.. Moyle+ and thee .01 he gone only une day Nov. who could dB, le that'

A Success Recipe

VE netunall, ttho ran he • pet ter Ilene man, meet... •.ruld I Add each veer' Whet. I do .ith th• nunut SEA, d. find weal," Ito

u. hotels or other Walther No grmage of WIT muter, ma, re

.r thernaeler• u • chapter out/ 0

...cud., functioned t, an SCrE muting...up and lulfilld tome dud. and have reworeenent•

WEI...NI • owe'''. Ur the Loehr,. tt the Need,

tour.. ostler Ile et...mot the Nerd, mean... • onunelment ha• Aren nub to ulun

• Low-cost technical seminars are of-fered bi-monthly by the Society's 33 Chapters and Meeting Groups across the country.

BCT/E Certification

the INTERVAL

Zit

Getable Ind

Broadband Communications lbchnician/Engineer Professional Designation Certification Program

System muugers muet rurognue and gerund beau knowledge Tilt the needier oat* terfourodu to our c•ruhrateka Outdd he an tuportant Mo.., and lard S., NO mpg, to goal lor every CATS ter heurtan ead the Sc., • efforts fly mcour..• puttegdnues the uturet bend. from Ito* Luff Ku., • knowledgeable and row. Safer VC. Preudent Eng....rug taunt employee and the todowlual Ported Am, Teary., Cort, benefit@ horn the and Ice,. noun that the BCT E comfiest. more», Eduard Allen Pnruckett. Wee.. onunur.

W.I. It.. many new challenge. far ',then.. tau, greater mot. to mud plac. on the poleeranal ogreateon of our eye., SCTE • coda..., Poor.. nil ...yaw., rote u, the room.. development of unwed «cede, Jame. Mom« Prude., Nunn., rd. Illeuerro Arc. • on

laduetrywde cartahrawon t• un reptant tegeorue•chalitegr• too' roan yudreerk of weluted menrourtay

At it. lut mutt, the ACTA Endured.. Coronuturunaurnoody ,oued towel.» the Noce, • BerP (endue.. Program a• • reuse:4o ud ouch marled ten, to Ow unlue we Infer, many member* of therm nut.. Weedy have take, one c• more of the •aarnmatued

it, Mahar Cwsora Vt. Prudent A.. Terhoolgoe• ATE

Chum., SETA fingtmuutg Como. we

Neal Barley Ente Pneeleot Suer. •hel Iterhoology ACTA

Eagles...mg Cocrundue ht-t-.

SPECIAL ISSUE PULL OUT AND SAVE

• The BCT/E program is designed to encourage personal development, to recognize individuals for the demonstration of technical knowledge and to assist manage-ment in their hiring and promotion process.

JOIN US TODAY! Call (215) 363-6888, or write for information and an SCTE brochure:

Publications

And Videotapes

the Ful INTERVAL

-Special Issue

I»

Society of Cable Television Engineers Publication and Videotape Price List

Includes important information regarding

.= • Educational Publications

7=--- • Videotapes

• Audio 11.anscripts

= • New Products

PULL OUT AND SAVE

• SCTE offers technical training manuals and videotapes for pur-chase, plus, national members receive corporate rate discounts on many other valuable services.

669 Exton Commons Exton, PA 19341

The Society of Cable Television Engineers, Inc.


tion of interference when it occurs. A simple phone call from the complain-ing activity can establish whether the cable system carries any frequen-cies that could cause interference. If so, action can be immediately initiated to confirm or disprove the allegation and correct any possible problem.

2) Each cable system that is in a prescribed geographical relationship to specific navigational aids in the 108 to 118 MHz air navigation band will operate with a minimum character offset of 25 kHz from the local navaid frequency. The results of the Boulder studies would indicate that such an offset would absolutely preclude interference under any conceivable cable system failure mode.

3) Each cable television system that operates carriers in the frequency range of 118-174 or 216-300 MHz shall offset appropriate carriers a minimum of 50 kHz from the emergency frequencies of 121.5, 156.8 and 243.0 MHz. These are the aircraft and marine distress frequencies where, under emergency conditions, power and frequency stability of the emergency transmitters may be marginal. This proposal is designed to give maximum protection to these frequencies.

4) NCTA does not feel that adequate standards governing leakage from cable television systems can be established at this time. The levels need-ed to protect voice communications to aircraft have not been established. There is desirability for leakage monitoring but sufficient reliable field data is not available to relate the current practice to the levels necessary. NCTA proposes and will cooperate fully with FCC/FAA and others in responsi-ble programs of data collection looking toward the development of suitable techniques and standards.

5) NCTA feels that the features of a frequency plan that can reduce the probability of interference (namely acknowledge a frequency in use and frequency offset from those of crucial safety services) have been incor-porated in the recommendations, therefore a total frequency allocation plan need not be imposed or agreed upon now for the purpose of con-trolling interference. It is NCTA's opinion that the desirability of any form of frequency plan for other purposes should be addressed in a separate form and a separate proceeding. These proposals cover only the frequencies below 300 MHz since lit-

tle, if any, use of the frequencies above is now being made. NCTA will ad-vise the industry of the proper precautions to be taken when frequencies above 300, particularly those in the glide scope range of 328.6 to 335.4, are planned.

This brief summary given is a general idea of the steps being taken by NCTA on behalf of the industry to present comments on Docket 21006. The comments themselves are substantial and are a matter of public record. When and what the FCC will rule is still unclear. Liaison with FCC, FAA and others is continuing through NCTA and industry representation. Whatever the outcome, the basics of the situation will to some greater or lesser degree fall upon the industry for future implementation.

What to do

The question is really: What can we do to 1) avoid possible interference problems and 2) improve our system operation by reduction of both in-gress and egress in the cable system?

First of all it is obvious that for everybody's benefit more comprehen-sive techniques and systems must be developed for maintaining system RF integrity. Devices such as The Sniffer and the Cuckoo seem to be workable approaches available today. Surely other monitoring systems will appear as the need increases. In this writer's opinion there is no substitute for continuous monitoring by service vehicles on routine travel through the system. The direct benefits in location of illegals, reduction of CB interference, and the like will pay for much of the investment and time required.

Construction and maintenance practices also are important. There are a number of specific system problems that lead to leakage. The "wed-ding ring" crack, which generally occurs in connection with expansion loops, finally circles the cable and eventually completely fractures. Since the separation of the crack depends a great deal upon temperature, the amount of leakage varies from day to day. Larger expansion loops may be the answer. Proper lashing is important. At times, lashing cable has been known to wear through the cable sheath. Squirrels chewing the alum-inum on the top side is a problem in many of the southern states and

Single Channel

CADCO

If

Sub-Low Through Hyperband

Modulator 250B

,..ER MODULATION. AJU.0

ErVIDEO MOD c „, a .. c . e MODULATOR 250B

OU ,PfLEFEL 20 11Jig •-•

Features

Output Channels T7 through XX (5 to 440 MHz) Standard, HRC or IAC and FCC Offsets SAW Filtered +60 dBmV Output using Low-Distortion Hybrid Amplifiers Phase Lock Loop FM Audio

LED Audio/Video Indicators

4.5 MHz Subcarrier and Baseband Inputs

External Separate Audio/Video and Composite IF Loop-Through

kit

fill

COCO


2706 National Circle Garland, Texas 75041 Phone (214) 271-3651

Model 250B is affordable and backed by a two-year limited warranty.


Now MMDS Operators Don't Have To GoThrough Channels To DoubleTheir Channels.

o GENERAL ELECTRIC

CONVERTER

eCOMIA111)» DECODER

WC* LOC.

• se

CNANNEL PARENTAL SPECIAL BLOCK ED CONTROL EVENT

H A NNE L

•

The Comband System. Forget about red tape. Because now you can take channel expansion into your own hands.

All it takes is the Comband system from General Electric.

The Comband system is a necessity for all Multi-channel Multipoint Distribution Service operators and Instructional Television Fixed Service operators. Because its unique two-for-one technology lets you quickly double the channels within your allotted bandwidth.

The system also offers other features that will enable your operation to reap greater profits. It's flexible, stereo-ready and contains an unsurpassed one-way addressable baseband system. Plus the


Comband bandwidth compression process makes signal theft virtually impossible. Unauthorized pro-grams cannot be seen or heard.

The modular design of the Comband system allows you to control when, and to what extent, you upgrade your operation. So whether you're planning to enter a market or planning to capture a larger share of one, you can do so with minimum time and expense with a Comband system.

Before you make any further plans, see the Comband system in action. Call Ron Polomsky at 1-800-432-2253 to arrange a Comband demonstration.

Because when it comes to doubling the capabili-ties of your operation, we're the authority.

"GE" and "Comband" are registered trademarks of the General Electric Company.


CableTek Center PRODUCTS, INC.

850 Taylor St., Elyria, OH 44035

(216) 365-2487

1-800-562-9378

High-Security

Residential Enclosures

Molding Duct and Riser Guard

Fittings

Tee's Right Angles Inside Corners Outside Corners End Caps Reducers

Oulckstall GFMD GS0 GFG

Call or write for our complete catalog of protection and security installation products.

COREPREP 5

Coring & Stripping Tool

Interchangeable Blade Sizes

.412 .500 .625 .750 .875

Colors

Beige Brown Gray Redwood White

a difficult one to find. The same goes for pinholes caused by lightning. The pinholes usually occur between the messenger and the cable and allow leakage at that point. The largest single problem is the deformation of the cable in a "non-

RFI" connector. The right solution for this is to use only RFI connectors in construction. In older installations, patch kits have been devised. Pro-per installation of these patches is essential.

Amplifier housings need good RFI braid around the covers. The covers must be installed with a torque wrench for proper pressure. F connectors remain a principal source of problems in modern systems. F connectors should employ long sleeves and hex crimps or equivalent, which supply evenly distributed pressure around the fitting. Poorly designed ground blocks with no through ferrule produce poor RF integrity due to corro-sion. Damaged baluns, broken drop cable and the like are also sources of RF leakage.

It is felt that the industry's first reaction should be to take this problem seriously. This serious attitude should result in the implementation of con-tinuous monitoring techniques and upgraded construction practices as soon as possible. A firm decision "to do it" is the crucial step. The other end of the story is that if by chance extremely stringent regula-

tion is imposed, much of the cable plant now in operation may be con-demned. Therefore, it certainly behooves us to upgrade our construction practices ASAP to keep such problems (and rebuilds) to a minimum. Whether regulations are that stringent or not, one would expect to see a fairly complete cleanup of cable plants within the next five to 10 years and the sooner the better for all concerned.

In summary, the cable industry is now in the midst of a multifaceted prob-lem (if you care to refer to your taps as "spigots" you might call it a multi-faucetted problem), which affects our quality of service and may affect safety of life services. We do have problems and pressures, however, we do have some answers. We must "tighten up" our CATV plants and keep them tight under a good monitoring program. For this we can expect bet-ter quality, high customer satisfaction, and perhaps even more penetra-tion and approval of better rate structures. RI

R.T.G.* VERSALIFI'S - Ready for You • Right Now! When you need a lift in a hurry, call your Versalift Distributor. He has fast access to our R. T. G.* pool of complete, mounted Versalifts. No

waiting because of long delivery on vehicles, manufacturing delays, or

freight problems. Best of all, they're Versalitts, with job-proven

reliability and industry-wide acceptance. And, since we're mounting them in quantity, the

For the name of your Versalift Distributor, call:

111/11E MANOF ACYUPING COMPANY

P.O. Box 20368 Waco, TX 76702-0368 (817) 776-0900

prices are right, too. Truck or van

mounted, telescopic or "elbow" models, with working heights up to

55 feet, all ready to go to work —

N OW!

IMIS>AUF

*Ready To Go Mounted on current model chassis.

See a new Versa Lift at the NCTA Show. Reader Service Number 67.

CALL THE LEADER IN THE CATV INDUSTRY

àf TOLL-FREE 800-327-9767 (IN FL.) 800-433-0107

REPLACEMENT COMPONENTS

REPAIR

UPGRADE With confidence in our products, money back guarantee,

experienced personnel and a proven track record, why would you settle for less?

WHEN ONLY EXCELLENCE WILL DO!

IF YOU WOULD LIKE TO RECEIVE OUR NEW 1987 CATALOG—CHECK HERE

QUALITY R.F. SERVICES, INC.

850 PARK WAY

JUPITER, FL 33477

*Replacement Components* *Upgrade Electronics* *Repair Service*

System Name

Address

City/State

Telephone (

Your Name

Equipment Used in System

Position

ZIP

Please: CT 5/87

Send Replacement Components Catalog

I: Send information on repair service.

CI Send information on Circuit Boards to increase your channel capacity.

DMV ee us at the N the CATV Fremont Booth 1556.

CLI: Accumulating the data By Bruce Caner Fund Engneer Manager. Jones Intercable Inc

Over the past year and a half, Jones Intercable has completed ground-based cumulative leakage index (CLI) testing on 73 systems in the man-ner prescribed by the FCC. To date, six of those systems have completed their second test. Those tests have yielded some very interesting data. Before discussing the results and my observations, let's take a brief look at the philosophy behind CLI.

Cumulative leakage index is a way of determining and assessing the signal leakage integrity of cable plant. Signal leakage from a cable system represents an interference to over-the-air users of common frequencies and can affect the safety of aeronautical and emergency service users. Breaking down the phrase "cumulative leakage index" may give us a better understanding of the underlying theme behind the test. The word cumulative suggests something that is made up of ac-

cumulated parts, something additive. In fact, the test is aimed at assess-ing the cable plant's potential of interfering with the communications and navigation systems of aircraft passing through the airspace above. Leakage overliesthe system in a "lumpy umbrella" shape. The level of interference is made up of the cumulative or accumulated effect of all of the leaks in the plant, not just one or two big leaks (although the larger leaks are ob-viously major contributors). The next word in the phrase is leakage, which simply refers to a breach

in the plant's mechanical integrity that allows RF energy to escape its closed medium and to travel paths other than intended. The most common source of leakage you will find anywhere, in any system, is the "F" connector.

Next up is index, which indicates measure. The index that the FCC will use is 64. That number was established through testing to determine the level of RF interference at specific altitudes that actually would interfere with aircraft operation in the vicinity. Testers eliminated leaks of less than 50 i.tV/m (properly measured on the ground at 10 feet, etc.) as potential problems for aircraft, although these leaks still must be dealt with. If one follows the test procedures outlined by the FCC, applies the data to the CLI formula, and comes up with a number less then 64, one can be reasonably assured that the cable plant tested will not interfere with air-craft communication and navigation systems. Thus CLI is a test designed to assess the overall signal leakage integri-

ty of a given cable plant at a given "instant" in time. The test takes all leaks of a certain minimum level into account and yields a "figure of merit." The potential for that plant to cause harmful interference is measured against an index of 64. In order to truly assess signal leakage integrity at a given point in time, the test must be conducted as quickly as possible; ideally all facets of the test would be conducted instantaneously.

Why do CLI testing? Why on earth would anyone want to conduct such a test? To just arrive

at a figure of merit, one must parade past at least 75 percent of the total plant, including the known worst areas, stop and measure the leaks found with a dipole antenna and signal level meter, and do it very quickly. Then the data must be analyzed and input into a formula, and finally a "CLI" can be calculated. Now that you have your CLI number, what good is it? Without follow-up not much, but just as the signal level meter and sweep system are useful tools, so too is CLI testing. The cable industry became self-regulating with regard to signal quality and now should deal aggressive-ly with the signal leakage issue, if only in the interest of professionalism. Since the test identifies sources of signal leakage (egress), it identifies sources of RF and moisture ingress as well. Fixing these breaches in plant mechanical integrity smoothes out the frequency response of the system and improves picture quality. That keeps subscribers happy—which keeps them connected to the system and their money coming in.

Repairing the leaks also will reduce service calls—a basic non-revenue producing activity—and help to shift maintenance efforts into a preven-tive mode and away from a reactive one. Operating the plant in a preven-tive maintenance mode not only demonstrates a professional approach to conducting business, it lengthens the life of the plant. This in turn can ward off rebuilds and help to preserve the value of the asset.

Data obtained from the CLI test also can be a useful way to help deter-mine the need for rebuild activity and to secure the necessary funds dur-

mg the budgeting process. The list of good reasons for conducting CLI tests goes on and on. Basically, the test identifies problem areas that can directly affect picture quality in a cable system. The reasoning behind CLI testing also revolves around a safety issue that we all should be conscious of and concerned about as professionals. Remember, too, that the test for signal leakage conducted for years in

conjunction with the annual proof-of-performance test has, for the most part, consisted of throwing up a dipole antenna at the three widely separated test points (including the longest cascade) and measuring for leakage. I suggest that we have not been conducting thorough signal leakage tests. (Some people do quite well with routine monitoring, however, there is a difference between routine monitoring and testing.)

Results The results described here represent data collected from 73 cable

systems that conducted full CLI tests in the manner prescribed by the FCC. The technical demographics of these systems vary widely. Results are of-fered only to give an idea of what to expect. Keep the location, age, mechanical condition and electrical make-up of your system in mind when drawing parallels. The following numbers resulted from "full CLI tests" consisting of driv-

ing/walking out the plant, measuring the leaks found with a dipole anten-na and signal level meter, entering the data into a computer and calculating figure of merit, and returning later to repair all of the leaks found (including those less than 50 µV/m). All labor and materials are included. • Only 70 percent of systems tested passed with a figure of merit of 64 or less on the first test. • Average leaks per mile: very leaky plant = 4.0 or more moderate = 1.1 very quiet plant = 0.3 or less • Cost of test equipment varies according to size of plant and type of equipment selected. Test costs ranged from nothing to an approximate 9 percent increase to the total cost of the project. • The total repair cost per leak varies a great deal with percentage of backyard easement (systems with 75 percent or more of their plant in backyard easement should increase these costs by approximately 10 per-cent), number of leaks found, quantity and type of materials used, etc. A rough figure of $59 per leak was derived from our tests, which yields an approximate budgetary cost per mile of: very leaky plant = $236/mile or more moderate = $64.90/mile very quiet plant = $17.70/mile

Observations One of the most interesting observations arising from the tests concerns

systems that still use pressure taps and/or non-RFI sleeve connectors. I would have expected that these systems would be prone to more signal leakage and would yield higher figures of merit. But that is not the case. We have found that as long as diligent preventive maintenance is per-formed, older plants do not leak any worse than newer ones. In fact, if a newer system was the victim of poor construction techniques, it may leak worse and cost more to maintain. For this reason, it is a good idea to conduct a quick, abbreviated CLI on all new extensions. One is then able to point out craftsmanship difficulties to those building the plant before too much time has passed. We have found that the second pass-through (testing conducted an-

nually) does not necessarily turn up fewer leaks. The first pass identifies the largest leaks, some of which are masking smaller ones. The figure of merit does come down, but at least two passes are necessary to bring the number of leaks down significantly. Conducting a CLI test and repairing any leaks found on 100 percent

of the system (the only approach I recommend) does improve delivered picture quality and reduce service calls. The degree of impact depends on the severity of the problem that existed in the first place. For example, one average 10,000-subscriber system performed 340 service calls a month before conducting a CLI test and repairing the leaks found: 340 calls x $35 per call = $11,900. After completing the work, the system's


Reader Service Number 69. call dropped to around 300 per month, representing a savings of $1,400 per month or $16,800 per year. The cost for this particular system to conduct the CLI testing was only

$2,000 because all of the plant is accessible from the road. Testing was paid for in about a month and a half. Almost every one of the service calls saved probably would have dealt with ingress as evidenced by the decrease in that category of call. Most important, the system shifted those repairs from a reactive maintenance activity to a preventive effort and made immediate improvement in delivered picture quality. As might be expected, somewhere between 80 and 90 percent of the

leaks found are drop-related and the vast majority of those are caused by "F" connector problems, primarily looseness.

Before we started the testing on a companywide scale, I anticipated that chief technicians might wind up spending a great deal of time calculating CLI from their test results. To expedite the process. I developed a macro-driven, Lotus-based computer program that handles the calcula-tions and serves as a signal leakage log as well. It has proven to be a useful tool. (Jones lntercable will make this program available, along with the accompanying documentation, at no charge. To receive it send a format-ted 31/2" or 51/4" disk and a self-addressed, postage-paid mailer to: Bruce Cafter, Jones I ntercable, 9697 E. Mineral Ave., Englewood, Colo. 80112.) Jones lntercable has conducted these tests for a year and a half and

we have learned that there is no time to spare. The FCC deadline for sub-mission of results indicating that the cable system has been tested in ac-cordance with the rules—and has passed—is July 1990.1believe that the best reasons for conducting signal leakage testing have nothing to do with pressure from the FCC, but rather stem from our industry's concern for professionalism and public safety.

At the outset, the cumulative leakage index test was viewed as an onerous, expensive, labor-intensive task—and it is. CLI testing can create a scheduling problem because of the typically heavy, temporary man-power requirement. However, the benefits far outweigh the obstacles. The real burden is in educating operations management on the value of shift-ing reactive maintenance activities to preventive ones. Fî

Prevention is the only protection Lightning rods attract lightning— that's their function. The only sure protection is to prevent the lightning from striking the structure and damaging the installations inside. That's what the VERDA Lightning Deterrent does—it gives you protection from all lightning-associated problems by deflecting lightning. A positive corona is formed which deters positive lightning energy. The VERDA Lightning Deterrent can be applied in all situations requiring lightning protection—

Communications systems— microwaves—two-way radio —TV—FM—Nurad antennas —boats—police and fire stations—ambulances— telephones—trucks— It's round-the-clock protection against lightning.

This system has been storm-tested on the highest structure in the world

6 Lightning Deterrent Corp. 5321 South Kedzie Avenue Chicago, Illinois 60632 (312) 434-7912 (800) 241-2360 Ext 532

The Proven Lightning Deterrent!

LANCA "L" SERIES DIGITAL TIME DOMAIN REFLECTOMETER

The LANCA "L" Series Custom Digital Time Domain Reflectometers provide a real breakthrough in PERFORMANCE and PRICE. These reliable and versatile test instruments are light weight, rechargeable battery operated, compatible with most dual channel 60 megahertz oscilloscopes and can be programmed and calibrated by the user to meet specific test requirements.

Digital (DTDR) Test Mode: Standard on all models—Pressing key "4" on the Keypad will cause the Digital Test Mode to run a one time test of the cable and display the cable condition as: "OPEN", "SHORT" or "OK TO" in feet, metors or nanoseconds.

Analog (ATDR) Test Mode: Standard on all models—Pressing key "5" on the Keypad will cause the DTDR to enter the ATDR Mode. This mode requires the use of a dual channel 60 megahertz oscilloscope in conjunction with the DTDR. Test Pulse Widths are selectable as: 15ns, 150ns. 110Ons or 37 microseconds. This mode is used to detect pulse reflections that are smaller in magnitude than opens and shorts or to examine the shape of a reflected pulse. Examining smaller reflections allows the user to distinguish connections, taps, etc. and to map out networks.

FOR COMPLETE INFORMATION CONTACT:

Calibration Mode: Standard on all models—The calibration mode enables the user to set up the DTDR to test cable types with different dielectric characteristics (nominal velocity of propagation). Any known velocity of propagation speed can be entered in the "Set" position using the Keypad. Reader Service Number 70.

r irr7 Dealer/Distributor Inquiries Welcome

LANCA INSTRUMENTS, INC.

COAXIAL CABLE TEST INSTRUMENTS 1350 JOHNSON LANE / ROUND ROCK, TEXAS 78664 512 / 388-1195


Figure 3: RF analog optical receiver

fiber. If a fiber cable is broken, there are no sparks to cause fires or explosions and no chance of electrical shock.

Small size and weight: A single conductor fiber-optic cable weighs about nine pounds per 1,000 feet. A comparable coaxial cable weighs 80 pounds per 1,000 feet. Thus, weight-conscious designs can save precious pounds without a sacrifice in signal capacity.

Security: Electronics ' bugging" depends on electromagnetic monitoring; fiber-optic systems are immune to this technique. They must be physically tapped to extract information, which decreases signal levels and is readily detected.

FDM analog system A block diagram for an FDM (frequency divi-

sion multiplexed) analog transmission fiber-optic link is illustrated in Figure 1. The major system components are: 1) the optical transmitter, 2) fiber-optic cable and 3) the optical receiver. 1) Optical transmitter An optical transmitter accepts the individual

RF FDM analog inputs and provides the signal conditioning necessary to drive the semiconduc-tor laser diode. Figure 2 shows the major optical

transmitter functional components. First, an RF combiner sums the multiple analog inputs that are to be transmitted. The RF levels for each car-rier should be equalized prior to the optical transmitter Otherwise, optimum noise and distor-tion performance for each carrier will not be achieved. However, a slope compensation stage may be provided after the combiner stage to ad-just for normal cable slope effects. Broadband amplifiers with AGC (automatic

gain control) provide the necessary signal level to drive the laser diode. The RF drive level to the laser must be controlled precisely to realize the optimum system noise and distortion performance. A DC bias is applied to the laser to provide a

linear operating point. This bias current will deter-mine the average optical output power out of the laser diode, which is typically 0.5 mW for single-mode 1,300 nm lasers. Laser power is sensitive to changes in

temperature and laser aging. To preserve a con-stant average optical output power, two control circuits are commonly provided in the laser transmitter: a laser temperature controller and an automatic optical power controller.

A photodiode monitors the rear facet of the laser as a sample of the transmitted optical power and uses this information to control the laser DC bias current. Thus, if the laser average optical power changes due to time or temperature, the laser bias is adjusted automatically to maintain constant average optical power.

Laser life is adversely affected by operating at higher temperatures. Temperature control is accomplished by using a thermistor to monitor the laser temperature. A control circuit then drives a TEC (thermal electric cooler) to which the laser heatsink is mounted to maintain the laser at a con-stant temperature, typically 20°C. 2) Fiber cable Single-mode 1,300 nm fiber cable is preferred

for multichannel analog systems. This fiber has a core diameter of only 9 mm with an overall clad-ding/buffer diameter of 950 (typical). These fibers may be assembled into various cable assemblies that provide multiple fibers, strain relief and jacket options.

Fiber cable is available in lengths up to several kilometers per reel. For distances greater than several kilometers, the fibers typically are fusion-spliced to minimize path insertion losses. Single-mode fusion splices have typical optical losses of only a few tenths of a dB. Single-mode con-nectors have typical losses of 0.5 dB. The optical transmitter and receiver normally are connec-torized for convenience in servicing equipment. 3) Optical receiver The primary function of an analog optical

receiver is to reconvert the light power into an RF signal with a minimum contribution of noise and distortion. A block diagram is shown in Figure 3. The optical detector commonly employed for 1,300 nm analog applications is either an InGaAs pindiode or a Ge avalanche photodiode. The major distinction between them is that the avalanche diode has gain available (approximately 10), whereas the pindiode does not. The photodiode current drives a transimpe-

dance preamp that provides high input sensitivity and transforms the diode current into a voltage at its output. These preamps are available as DIP-packaged devices with fiber pigtails attached. A post-amplifier (with AGC) follows the preamp

to provide sufficient gain to obtain unity system gain for the entire FO link. AGC is utilized to main-tain a constant output level independent of op-tical input power that may change due to fiber resplicing. fiber loss vs. temperature, etc.

System perfomance parameters We now will discuss how several key system

parameters are affected by the respective f iber-optic system components. The parameters to be considered are carrier-to-noise, bandwidth and distortion. 1) Carrier-to-noise (C/N)

Carrier-to-noise obtained at the end of the FO system ultimately will determine the baseband (video) signal to noise performance. C/N is pre-ferred over system signal-to-noise (S/N) as an FO link parameter, since the output of an optical receiver is an RF carrier.

Also, analog video can be transmitted via VSB-AM, FM or other modulation techniques. For a given C/N ratio, the resultant video S/N ratio is


TV EQUIPMENT MARKETPLACE

SPOTMATICTm You Can't Buy a Better

Ad Insertion System

This is the system everyone thinks of when someone asks, "What is the mos widely used random access ad insertion system?"

The tact is that there are more SPOTMATIC systems in use today than any other type of ad insertion system. The reasons are simple: high quality, proven reliability, unparalleled factory support and an unmatched array of features.

• Completely modular for easy expansion as system grows

• Interfaces with optional Ad Manager". billing and traffic software

Yee! 'Br sas.

-1:U• --•ffl• "lsr 1.:Zn , -111r•-ler,

• Expandable to 32 channels with 32 VCR's inserting ads

• Full random access or random pod operation • Front-panel keyboard or optional personal computer

control • Complete turnkey packages available • Quick delivery • Broadcast quality vertical interval switching • Automatic logging with advertiser-sorted printout • Automatic bypass of malfunctioning VCR • Automatic return to satellite in event of VCR or power

failure

Channelmatic, Inc , 821 Tavern Rd., Alpine, CA 92001. Or phone (800)231-1618 or (619)445-2691.


# immummummailmilip YIDCRRTE7

11 1

Like two systems for the price of one

A new concept in ad insertion allows low cost fully random access ad playback with one through four VCRs on one channel, two VCRs on each of two channels, or four VCRs shared between two channels. Features full stereo audio capability, preview bus, computer-adjusted audio levels, user-friendly CRT terminal interface for easy scheduling, advanced audio and video switching circuitry, front panel status display, and unlimited system expansion capability. Traffic and billing software available. Contact CHANNELMATIC, INC., 821 Tavern Rd., Alpine, CA 92001 (800)231-1618 or (619)445-2691


( FREE

CATALOG Write for our brand new catalog of television and cable system equipment Everything from automatic ad insertion to playback systems to audio and video switching to signal processing and control.

Complete product line listing with photos, block diagrams, and comprehensive des-criptions and specifications. Enough detail to spec out your own custom system. cata-log will become a valuable reference. And it's yours just for the asking. Write, call, or circle the bingo number. But do it soon.

Channelmatic. Inc. 821 Tavern Rd. Alpine, CA 92001 (800)231-1618 or (619)445-2691

Reader Service Number 75. }

BROADCASTER I'm PROGRAMMABLE VIDEOCASSETTE

CHANGER Access 15 cassettes to play in any order

Uses one Sony VP-5000 series 3'4" VCR Easy to program, stores up to a full week's schedule Highly reliable mechanism uses no belts, chains, gears Suitable for broadcast, cable, industrial, educational, and government installations for any multiple-tape playback requirement

ChanneLmatic, Inc. 821 Tavern Rd, Alpine, CA 92001 (800)231-1618 or (619)445-2691


ARE YOU THROWING MONEY AWAY?

Losing verification data is just the same as throwing money away, and who in their right mind would do that. Make sure when you run somebody's ad you get paid for it. The LOGMATIC°4 and LOGMATICJR.Tm logging and venfication systems always get their data when used in a system with SPOTMATIC JR. and LI'L MONEYMAKER low-cost ad insertion systems.

L °GAM TIC

L OGMA TIC JR. The LOGMATIC contains a 4000-event memory and

interfaces to an 80-column printer or to a PC for data re-trieval. The LCGMATIC JR. has a built-in 20-column prin-ter and real-time clock. It prints the event record as the event occurs. Both loggers feature automatic operation. and they record insertions on four channels. Call or write for more information. You don't have to

lose money for unverified spots. Channelmatic, Inc. 821 Tavern Rd. Alpine, CA 92001. (800)231-1618 or

(619)445-2691. Reader Service Number 76.

NETWORK SHARE SWITCHER

• Inserts ads into four networks from one ad

source.

• Inserts ads one network at a time on a first

corne, first served basis.

• Four Digital DTMF cue tone decoders.

• Four preroll delay timers one for each

network.

• Composit sync out put to facilitate vertical

interval switching.

• Cue tone decoder disable switches.

• Power fail relay bypass.

• Inputs and outputs for controlling ad

insertion devices.

il

NSS 4A NETWORK SHARE WITCH ER

CI IANNELMATIC, INC. 821 Tavern Rd. Alpine, CA 92001 (800)231 1618 or (6t9)445-2691


LIKE GETTING YOUR MONEY FOR

NOTHING AND YOUR CHECKS FOR FREE

Make Money the Easy Way — Put either SPOTMATIC JR.". or [IL MONEYMAKERT, to work for you now. They arethe lowest-cost tools you can use to automatically insert local ads into cable TV programming. You have one unn controlling one VCR to put ais on one channel. Equipment overhead is very low. Switching occurs during the vertical interval for

broadcast quality transitions. Once the system is programmed by the operator, It operates automatically. The SPOTMATICJR. has a built-In printer for

verification records; however, both the LI'L MONEYMAKER and SPOTMATIC JR. inserters connect easily to a LOGMATICT. logging and verification system. With optional software, this enables computerized data ref heval and automated billing and report generation. Write now to see just how little it takes to get into automalic ad insertion.

Channelmalic, Inc. 821 Tavern Rd., Alpine, CA 92001 (8001231-1618 or (619)445-2691


Does the high cost of monitor switchers have you behind the eightball? Then you need to

PUT AN EIGHTBALL'm UNDER YOUR MONITOR-8x1 Very Low Cost Switcher It is an integrated circuit-based monitor

switcher featuring broadcast quality stereo audio and video switching. Lighted momentary contact pushbuttons are field-legendable. Its cost is far less than any other comparable unit on the market. Write or call for information today.

CHANNELMATIC. INC 821 Tavern Rd Alpine, CA 92001 (8001231.1618 or (61914452691



a function of the modulation approach. Wide-band FM provides higher S/N ratios at the sacrifice of utilizing greater channel bandwidths. The optical transmitter will have an impact on

C/N in two ways: 1) setting of a particular modula-tion depth and 2) inherent laser source noise.

For an analog system, a time-varying signal, S(t), is used to directly modulate the optical source about a bias current point (Is) as shown in the laser LI curve (Figure 4). With no signal input, the optical output power is Pt. When the signal S(t) is applied, the optical output power, P(t), is:

P(t) = Pt [1 + m s(t)] (1)

Where m is the modulation depth defined by:

Is'

Is' = —

Where IT = laser threshold current

(2)

The parameter A l is the RF variation in cur-rent about the bias point. To prevent distortions in the output signal, the modulation must be con-fined to the linear region of the curve. Further-more, if A I is greater than Is', the lower portion of the signal gets cut off and severe distortion results. Typical m values for analog applications are .25 to .50. A higher modulation index (m) will provide a

higher RF C/N ratio since the received RF car-

rier is proportional to m. Thus, a direct tradeoff exists between system distortion and noise per-formance as contributed by the optical transmitter.

Inherent laser source noise defines the max-imum achievable C/N obtainable from a laser transmitter. Minute fluctuations in optical emis-sion are exhibited when biased above threshold. This noise phenomenon is referred to as relative intensity noise (RIN). The intensity noise is neither thermal nor strictly shot noise in nature. It is the response of the laser to modulation by intrinsic shot noise that results from the granular nature light and electricity. Typical values of laser C/N due to RIN are —120 to —140 dB/Hz. The optical loss budget analysis is the conven-

tional approach used for determining the max-imum optical path loss. A loss budget compares the optical power transmitted with the minimum optical power at the receiver to provide the re-quired C/N ratio out of the receiver. The difference between these two quantities is the optical loss budget allowable for the total path loss. A typical analysis is shown as follows:

Power launched (Tx) Fiber loss Splice loss Connector loss

Received optical power (Rx) Received sensitivity (Rx) (minimum power allowable to provide required C/N)

System margin

CABLE DESIGNATOR

"SIX PAK"

model

2901B+

model

525

with...the ability to transmit

through taps and splitters!

• Identifies unique cables within a bundle of cable. • Has the ability to transmit through taps and splitters making previously installed cable easy to identify. • Identifies home run bundles in apartment buildings. • Identifies multiple cables at one time.

$395

DIGITAL

TIME DOMAIN REFLECTOMETER

CABLE FAULT

LOCATOR

with...SCOPE OUTPUT CAPABILITY

$795 manufactured in the USA by Riser-Bond Instruments

3430 Fujita Avenue Torrance, California 90505-4078

Lii i,r (213) 539-8030 in Calif. 18001641-2288 Outside Calif. (800)551-2288

—3.0 dBm 20.0 dB 2.0 1.0 dB

—26 dBm —30 dBm

4 dB

One might ask how the C/N performance of the system will change as a function of optical input power. The answer depends on whether the system noise performance is receiver limited, quantum noise limited or laser source noise limited. The C/N present at the output of an op-tical receiver employing a pin-diode is:

(1/2N2Xm x Ro x Rt)2 C/N -

(RIN R02 Pt, B)+2q(Ro Pt+Id)8+(44 %Meet

(source + quantum + receiver)

where Ro =

Pt

Id 8

=

Ft RIN N

diode responsivity = modulation depth = average optical power received = electron charge = Boltzmann's constant = diode dark current = bandwidth of receiver = temperature (°K)

equivalent resistance of photodiode load and amplifier

= noise factor of preamplifier = source relative intensity noise = number of FDM channels

(3)

When the optical power incident on the photodiode is low the receiver circuit noise term dominates the system noise, so that

C/N _ (1/2N2)(m x R, x pt)2

(4Kb Ts/Reg)Ft (4)

f N Factory Authorized

WAVETEK METER REPAIR

FAST AND EFFICIENT SERVICE

- SAM

• • o D)-4. —Mr

Ail&' Now available on thi

WEST COAST

CAW SERVICES

Outgirlp

800/227-1200

800/223-3152

\ 2.211 Warm Springs Court, Fremont CA 94539i

See us at the NCTA Show. Booth 1556. Reader Service Number 81. See us at the NCTA Show. Booth 1712.


GET THE PICTURE NOW!!!

If you want to get the Whole Picture, you need to look at the ISS GL-5000A Satellite Receiver and see some of the features you might be missing.

• C/KU Band Switchable • 950-1450 MHz Downconversion Format • Extended Threshold with low, low C/N • Internal Notch Filter • Special Versions for International, Subcarrier Programming and

Extreme TI Environment applications.

To GET THE WHOLE PICTURE, call today to arrange for an evaluation unit and get the answers to your headend needs from one source.

ISS ENGINEERING, COMMITTED TO EXCELLENCE

ISS ENGINEERING 104 Constitution Drive #4 Menlo Park, Ca. 94025 (415) 853-0833

800-227-6288

!SS/EAST 434 Westchester Drive Birmingham, Al. 35215 (205) 853-6919

800-351-4477



Figure 5: C/N vs. received optical power

120

110

N

90

Source limited

1 dB/1 dB

Quantum limited

2 dB/1 dB

Receiver limited

-10 -20

Optical power (Pt, dBm)

-30 -40

Here, C/N is directly proportional to the square of the average optical power. Thus, for each 1 dB change in optical power received, the C/N ratio will change by 2 dB. For larger optical signals incident on the photodiode, the quantum noise associated with the signal detection pro-cess dominates (assuming Id negligible), so that

C/N (1/2N2)(m2 x R, x Pt)

(2qB) (5)

Since the C/N ratio in this case is independent of circuit noise, it represents the fundamental or quantum limit for analog receiver sensitivity. In this optical power range the C/N ratio will change

1 dB for each 1 dB change in receiver optical power. For very high optical power levels the C/N ratio may be limited by the laser source.

(1/2Nz)(mz) C/N -

(RIN x B) (6)

Thus, the C/N ratio is constant at the maximum obtainable from the laser transmitter. Figure 5 il-lustrates an example of C/N obtainable at the receiver output as a function of optical input power when these noise sources are present. 2) Bandwidth limitations

Laser transmitters have available modulation bandwidths of at least several GHz. Typically the transmitter circuitry will limit the upper bandwidth rather than the semiconductor laser diode. However, linearity constraints will tend to limit full utilization of the available bandwidth in analog FDM systems. Single-mode 1,300 nm fiber has bandwidths

above 10 GHz/km available. The electrical 3 dB bandwidth for a single-mode fiber is

f(3 dB) = (.35)/(M x A Xx L) (7)

where: M = material dispersion (ps/nm x km) AX= optical spectral width (nm) L = fiber length (km)

For 1,300 nm single-mode fiber:

M = 3.5 (ps/nm x km)

UNTANGLE YOUR SUBSCRIBERS!

No more tangled cables. No more bulky switches. No more confusion with changing connections.

GIVE YOUR SUBSCRIBERS PUSH-BUTTON VIDEO SELECTION CONVENIENCE... 4 RF Inputs to a TV Set (Cable TV, Outdoor Antenna, Satellite Receiver, VCR, Video Disc Player, Video Game, Computer). View a scrambled channel while at the same time record unscrambled channel, or vice versa. TV Remote Controls can be used.

RMS GIVES YOU TWO VIDEO CONTROL CENTERS!... Model VCC-1, and Model VCC-11A Amplified.

For more information- contact your RMS Account Executive...

RMS ELECTRONICS, INC. 50 Antin Place, Bronx, N.Y., 10462 - CALL COLLECT: (212)892-1000 (New York State) TOLL FREE: (800) 223-8312 (Continental U.S.A., Puerto Rico, U.S. Virgin Islands)

See us at the NCTA Show, Booth 2705. Reader Service Number 83. , Copyright 1986 RMS Electronics, Inc.


Choose A STEL/SCOPE® And Make Everyone Happy Choosing an aerial lift that will satisfy the many different needs of your company's management team can be a difficult decision. And, unfor-tunately, it's a decision you'll have to live with for years.

Choose the wrong one and you'll hear about it—from everyone. Crews griping about jerky controls or how hard it is to reach a lot of poles and cables. Fleet service managers complaining about the way it seems to spend more time in the shop than on the job. And, when downtime records and maintenance costs start to pile up, financial management is going to start asking if that low-bid aerial was such a bargain after all.

The next time you're looking for an aerial lift, why not make it easy on yourself. Choose a Stel/Scope, the aerial lift designed and built to make everyone happy. Crews will like its smooth operation, the way it helps them get work done faster, with less fatigue and in greater safety. Fleet managers will like its low-main-tenance dependability. Financial managers will ap-preciate the savings realized in long term cost of ownership. And you'll like the peace and quiet that comes from choosing an aerial lift that makes everyone happy.

STELCO 5500 Kansas Ave. Kansas City, KS 66106

(913) 287-1500


Figure 6: spectrum plan to avoid second orders

Second orders

- f

Transmission spectrum

Second orders

fl + f2

250 MHz 500 MHz 1000 MHz

Thus, for a 10 km path with a single-mode laser (A X= 1 nm)

f(3 dB) = 10 GHz

High-sensitivity receivers require that band-widths be limited. As seen from the expression for C/N ratio (Formula 3), all the noise terms are directly proportional to bandwidth. For this reason the optical receiver will intentionally limit the bandwidth to only that required for the par-ticular transmission requirement.

High-sensitivity receivers also require high in-put resistances, as can be seen by the C/N ex-pression in Formula 3. Higher bandwidths are difficult to maintain at higher resistance levels, due to real and parasitic capacitances present in the optical receiver circuitry. Very wide-band

(>1 GHz) receivers typically utilize 50-ohm photodiode, preamp and post-amp stages that will provide lower receiver sensitivities due to the 50-ohm thermal noise source at the preamp input. 3) Distortion The limiting distortions in an analog FDM

system are second- and third-order intermodula-tion. Second-order intermods are defined as ti + f2 products. Third-order intermods are de-fined as fl ± t2 ± t3 products. The laser diode normally will be the distortion-

limiting component in a fiber-optic link. Typical values of distortion for a single-mode laser operating at a 50 percent modulation depth are: Second order, 30-45 dB; and third order, 45-60 dB.

The spread in values indicates that not all lasers have good linearity. Some lasers even may have abrupt discontinuities (kinks) in their LI curves, which disqualifies them completely for use in analog systems.

Circuit linearization techniques for lasers have not proven successful to date. A scheme that measures the non-linearity and corrects it in real time, such as feedback or feedforward, can be helpful here. However, at this time, careful specification criteria and selection of lasers for linear analog performance are an absolute re-quirement to obtain high-performance analog FO links. The linearity of fiber-optic receivers are

generally quite good since they operate at relatively low signal levels. Pin photodiodes have good linearity over several orders of magnitude. Well-designed preamps and post-amplifier elec-tronics will not contribute significantly to system distortions.

At very high optical powers present at the receiver input, it may be necessary to utilize an optical and/or electrical AGC. Fixed optical at-tenuators also may be used at the receiver in-put when the high levels are a permanent condition.

With prior knowledge of the distortion perfor-mance available in a FO link, a system designer can minimize some of the possible limitations. For example, since second orders are the strongest distortions, a frequency transmission spectrum that eliminates second orders from fall-ing in desired channels can be selected. Limiting

Permatrap /ILNOrthenst Filter Co., Inc.

albe/0111 nay,

CHANIYI,

Date Coding Stamped Into Metal Sleeve

• Nonremovable Crimped Sleeve. • Passband Range All Others. 600 MHz min. • Passband Range Low Band. 450 MHz min. • RTV Instead of -0- Ring Sleeve Seal.

Return Loss Typically 15 dB Min. 2 Elements More To Improve Return Loss.

• Rubber Connector Seal. • Rubber Male Pin Seal. • Improved Return Loss At All Frequencies To Improve Mach And Ability To Use Several Traps Without Signal Loss.

4 - Pole Sharp

Trap Product Type Single Channel Sharp

Lower Adjacent Rejection Sound (dB) Depth (dB)

Lower Adjacent Video (dB)

Upper Adjacent Video (dB)

SCS - 2, 3, 4, 5, 6 SCS - A-2, A-1, A SCS - B, C, D, E

SCS - F, G, H, I

SCS - 7, 8, 9, 10

SCS - 11, 12, 13

SCS - J, K, L, M, N, 0

SCS - P thru W

-4.0

-6.0 -6.5

-7.5

-10.0

-12.0

-15.0

-25.0

-65 -0.5

-65 -0.5 -65 -0.5 -65 -0.8

-65 -1.5

-65 -2.0

65 -3.0

-65 3.5

-0.5 -0.5

-0.6

-0.8 -1.5

-2.0

-3.0

-3.5

4 - Pole "Positive Traps"

Trap Product Type Descrambler Filter

Video Loss (dB)

Rejection Color Carrier Upper Adjacent Depth (dB) Loss (dB) Video (dB)

SCD - 2, 3, 4, 5, 6 SCD - A-2 thru D SCD - E thru I

SCD - 7 and 8

-2.5

-3.0

-3.5 -4.0

-65 -6.0 -0.5 -65 -8.0 -0.7

-65 -8.0 -0.7

-65 -12.0 -1.5

100% Urethane Filled

• Superior Sleeve Seal With Moisture Cure Adhesive. • Completely Shockproof. • Superior Temperature Stability.

Ar/111%

Northeast Filter Co. Inc.

1 WY/

Northeast Filter Co., Inc. 14 Corporate Circle East Syracuse. N.Y. 13057

PHONE: 315-437-7377 315-437-7378

FAX: 315-437-7879 MADE

IN U.S.A.

2 Year Warranty Free Color Laminated Label


Attn

: Greg Hayward

NO MORE HOLES TO DRILL!

The Ultimate Locator is NOT a Backhoe

C -0 0 0- — — (0

7, i c& 01:20•)_li,' >, 1,— no • — .5'

2 ro c o

& or 1 ro ? IÔ

a. 2 -0 te ,0 E at e te pe Y ex, Cre • — pe 0

Lai — C Li- ei) Lj 4— CN E E 00crIri)t)

o d ru > •••-• c c

D ... < v; c) c - el) b s- o >...„

=• 0 ima_ E0

• e è - e • ;*

. .‘, e •er . ••• '

E o

o

Cu

o

E -0

oo cc

a)

I) ( " a)

• (f)

coc)

e)

Eliminate costly trial digging & cable repair with Rycom's Model 8830 Buried Cable & Fault Locator.

Locate path and depth, shorts, grounds, crosses, and splits. Have all the features of a traditional locator but MORE

Look at these EXCLUSIVE features!

• A High Output Transmitter & a High Gain Receiver allow for 30 Miles of pinpoint accuracy detection.

• A Collapsible Ground Return Probe saves storage space in truck.

Send today for FREE

information or Call Toll Free

1-800-851-7347

Name Title

Company Phone

Address

City State Zip CT 5/87

mielerelum 1.1()iff ,..„,,.,,_....., RIF .

vwJ NOW OSTS AVAILABLEj.

IN BLACK

,

COMPARE! SAXXON ,sTEEL, PLASTIC

,GENERiCI SAX XON SAVINGS

FACTOR

RELATIVE LONGEVITY 5 (Galvaiume Steel) 1 (Easily degradablei 5 CLIP SPACING 18' • 24" 12' 1.5

WASTAGE 5% iMisses Bad hits) 20% for more) 1.25 THE SAXXON CLIP NOW COSTS YOU EVEN LESS!

The Sachs SC18 Saxxon clip is available for 6mm, 7mm and 8mm cables

elk • 30W SERVICE RD.CHAMPLAIN N.Y 12919-9703 1

SACH I FREE SAMPLES I

S e— CALL US NOW TO SEE HOW COMMUNICATIONS INC. YOU TOO CAN SAVE COSTS w

2

-800-361-3685 COMPANY

ADDRESS

a. NJ

- SPECIFY SIZE USED


UNITED STATES

BUSINESS REPLY CARD FIRST CLASS PERMIT NO. 127 DES PLAINES, IL


011ETÀF CLIP IT 1[Linx

201 SCOTT STREET ELK GROVE VILLAGE, IL 60007

At-tn: Greg Hayward

Name

Company

Address

City/State/Zip 1111

BUSINESS REPLY MAIL FIRST CLASS PERMIT NO 13158 KANSAS CITY. MO


, grycom® NE instrurrsients, inc.

9351 East 59th Street Raytown, MO 64133-9968

NO POSTAGE

NECESSARY

IF MAILED

IN THE

UNITED STATES

NO POSTAGE NECESSARY

IF MAILED

IN THE

UNITED STATES

BUSINESS REPLY MAIL FIRST CLASS PERMIT NO 60 CHAMPLAIN, NY


e SACHS Communications, Inc.

30 W. Service Rd Champlain, N.Y. 12919-9989

1-

piemAeH 6aio :

tiny

.oui Suo!leopnwwoo sHovs

Figure 7: Beat stacking for five-channel system

el RF

e2 #3

Channel spectrum

#4 .5

he transmission bandwidth to the highest oc-tave region will cause all the second orders to fall above or below the desired transmission spectrum (Figure 6). Without the second-order limitation, third orders will be the limiting distor-tion mechanism. As the number of channels increase above

three and are equally spaced, it is important to realize that there will be intermod or beat stack-ing. That is, several individual beats will exist at or near the same frequency. This is commonly referred to as composite triple beats (CT B). The result of beat stacking tends to be additive on a power basis (assuming the individual carriers are not phase-locked). Figure 7 illustrates this situation for five RF carriers. The cumulative ef-

fect of stacking can be estimated using the expression:

CTB = —d3 + 10Iog (N)

where: —d3 = distortion level of a single third-order

intermod (three tone) N = number of stacked beats (equal

levels)

The largest number of beats will fall in the center channel for a symmetrically spaced spec-trum. For the five-channel spectrum shown in Figure 7, there will be four (three-tone) third-order beats stacked in the center of the channel spec-

trum. Thus, the worst case third-order distortion would be 6 dB worse than that contributed by a single third-order distortion. Two-tone, third-order distortions also will be present with multi-ple carriers. However, they will have individual distortions that are 6 dB below a three-tone third-order product and thus tend to be a negligible contribution as the number of channels in-creases. These extrapolations are useful since many linearity tests are performed using a limited number of carriers.

Systems applications Analog FDM fiber-optic transmission systems

have been used successfully to carry up to 16 channels of video on a fiber link with perfor-mance approaching RS-250B (short haul). The most common modulation technique employed is wide-band FM ( > 7 MHz deviation). Wide-band FM modulation provides a signal-to-noise ratio improvement of over 20 dB compared to standard AM transmission. FM signals also have a high tolerance to intermod distortion. Whereas AM channels require channel distortion levels greater than —57 dB below the RF carrier, FM will operate with distortion levels of —40 dB. VSB-AM fiber-optic transmission systems have

successfully carried four to eight channels of video up to 12 km. Performance levels are com-parable to CATV standards. However, the cost per channel for an AM system is significantly lower than for video FM. F.P.e3

This article was presented at the RF Technology

Expo 87

0

D

0

le it

•

Communications

Visibility

Information

Knowledge

Reprints work for you. For more information on

this effective marketing tool, call Marla Sullivan at:

(303) 792-0023


Telstar 303. . .Galaxy 3. . .What's Next??

Up to $4500.00 cash back for your existing antenna farm when you purchase Simulsat. Simulsat ... the only antenna you'll ever need.

Call for details.

ANTENNA TECHNOLOGY CORPORATION



1140 East Greenway Street. Suite #2 Mesa, Arizona 85203

(602) 264-7275 Telex: 187217 - Intelex Telex. 187216 - Westel

PRODUCT NEWS 11111111111111111111111111111111111111111111

Spectrum analyzer IFR Systems is offering its Model A-8000 spec-

trum analyzer. Its synthesized RF section covers a frequency range of 10 kHz to 2.6 GHz with a time base accuracy of ±0.5 PPM. Scan width can be selected from 1 kHz to 200 MHz/division plus zero scan and full scan. Resolution band-widths vary from 300 Hz to 3 MHz and sweep times can be selected from 5 milliseconds to 10 seconds/division. A 10 dB, 2 dB or linear scale can be selected

on the vertical raster scan display and the log mode can be scaled in dBm, dBV, dBgV, dBmV and d6µW. There is 60 dB of internal attenua-tion and 65 dB of IF gain available to permit a displayed measurement range of —120 to 30 dBm. Two video filters, 300 Hz or 30 kHz, also

can be selected, as well as an average mode. For more information, contact IFR Systems

Inc., 10200W. York St., Wichita, Kan. 67215-8935. (316) 522-4981; or circle #125 on the reader ser-vice card.

Water removal The Water Guard dessicating packets from Oil

Maintenance Technology are said to remove moisture and condensate that accumulates in amplifier boxes or other closed areas and reduce the maintenance costs due to water problems. Packets are available in several sizes; custom packets can be made to fit specific needs.

For further details, contact Oil Maintenance Technology Inc., P.O. Box 1079, Channelview, Texas 77530, (713) 452-5732; or circle #123 on the reader service card.

Remote controls R.L. Drake is introducing a new line of pro-

grammable remote controls that allow the user to operate up to three different remote controlled

products from one module. The remote has a 30-foot range and only can be used with infrared (not ultrasonic) products.

To program the unit, the user flips the "learn" switch and places the module against the com-ponent's remote The function desired is pressed on both remotes; the Drake unit flashes a light

the O.K. BULL CORRAL

fvE r•rx.,Nr> A NeVAY Tc derrALIZE

E. Nev./ Aig R 'LE

(-we A FZEE Ankit NNA v./trf4

A 3 hict4T c7.1411t.-E Ue..121PriCKI.

1111111111111111-

to indicate it has learned the function. According o the company, the 41-function module can operate even the most sophisticated consumer electronics components.

For more details, contact R. L. Drake Co., PO, Box 112, Miamisburg, Ohio 45342, (513) 866-2421; or circle #133 on the reader service card

Feedforward amp Hughes Aircraft's Microwave Products Divi-

sion announced its new feedforward power amplifier, designed to extend the range of its AM L microwave line extender. The AML-FFA-160 is able to transmit up to 60 channels and provide the full benefits of feedforward distortion cancella-tion at CARS-band microwave frequencies. The 12.7-13.2 GHz microwave amp uses stan-

dard AML GaAs FET solid-state technology in a feedforward configuration. Housed in a separate temperature-controlled outdoor hous-ing, it provides the AM L-OLE-111 microwave line extender with up to 10 dB more output capabili-ty without further degrading the noise and distor-tion performance.

For more details, contact Hughes Aircraft Co., Microwave Products Division, PO. Box 2940, Tor-rance, Calif. 90509-2940, (213)517-6233; or cir-cle #135 on the reader service card.

Steel molding CableReady Inc. has introduced a two-inch

version of its Guardian galvanized steel molding. The new size has a 45 AG-6 capacity and is con-structed of 26-gauge galvanized steel like the company's one-inch molding, which has an 18 RG-6 capacity. Both sizes are said to be vandal-and weather-resistant. They offer security key re-entry for fast and easy upgrades. A 15-year war-ranty on each size also is offered.

For more information, contact CableReady Inc., 6820 N. Broadway, Suite E, Denver, Colo. 80221, (303) 428-9141; or circle #136 on the reader service card.

F connectors Gilbert Engineering is offering its new color-

identified F connectors to be used in conjunc-tion with color-identified drop cable produced by major cable manufacturers. The color ring on each connector identifies its size and is designed for easy installation and proper gripping of matching color drop cables. The connectors were produced originally to meet ICI specifica-

1

10e MAY 19Ei7 Courtesy Parallex


1111111111111111111111111 11 11111111 1111111111 1111 1111111111111111111111111111111111111111111111111111111111111111 11

tions, but now are standard catalog items available for general use.

For further information, contact Gilbert Engineering, P.O. Box 23189, Phoenix, Ariz. 85063-3189, (602) 245-1050; or circle #137 on the reader service card.

0.. to

L=SUNII 440 •

111 •

• • •

.j.j t ô ••••• • •

Signal level meter

•

b.

Sadelco's new Super 600 Special signal level meter shares many of the internal features of the regular Super 600, but now has a user-replaceable F connector on the front panel. The meter comes equipped with individual band il-lumination and a microammeter for improved night vision. An AFC control also is mounted on the front panel. The NiCad battery supply with auto shutoff includes deep discharge protection.

For more information, contact Sadelco Inc., 75 W. Forest Ave., Englewood, N.J. 07631, (201) 569-3323; or circle #141 on the reader service card.

DBS antenna Matsushita Electric, together with Comsat

Corp., has introduced a new flat Ku-band satellite antenna suitable for direct broadcast satellite (DBS) and fixed satellite service (FSS). Unlike a parabolic dish antenna that reflects microwaves off its surface and collects them, the flat anten-na receives microwaves directly. The antenna is said to be highly portable and

easily installed; its flat surface is resistant to prob-lems associated with snow and wind, and can

be colored or printed to order. The antenna comes in three sizes (1.2 foot square, 1.3 by 2.4 feet, and 2.4 foot square). It is available in left/right circular polarization and dual types.

For complete details, contact Matsushita Elec-tric Works, 10400 N. Tantau Ave., Cupertino, Calif. 95014, (408) 446-5010; or circle #128 on the reader service card.

Cable cement Silaprene M5038, part of a new line of cable

splicing cement from Uniroyal Plastics, is said to provide a secure and flexible bond for splic-ing high-voltage wires as well as other electrical cables. Its reclaim rubber base is quick drying and offers adhesion to rubber, non-porous metals and plastics surfaces. The product is available in black and can be

applied by spray gun or brush. Joining the spliced surfaces and applying pressure establishes a bond and ensures full contact. The dried adhesive can be reactivated with petro-leum naphtha.

For more details, contact Uniroyal Plastics Co. Inc., P.O. Box 2000, Mishawaka, Ind. 46544-1399. (800)336-1973; or circle #126 on the reader ser-

vice card.

Power supply Nova Electric is offering its Galaxy 5000, a

small 5 kVA uninterruptible power system. The module stands 83/4 inches hioh: its 7-inch hat-

tery pack provides up to 10 minutes of opera-tion at full load. According to Nova, the product employs reliable state-of-the-art transistor technology. Only two printed circuit cards are used to provide all necessary signal processing and control to the system's battery charger, in-verter and solid-state transfer switch.

For more details, contact Nova Electric Inc., 263 Hillside Ave., Nutley, N.J. 07110, (201) 661-3434; or circle #131 on the reader service card.

Lightning guard Lightning Prevention Systems is offering its

Model ALS-3000, designed to prevent lightning from striking any structure it is mounted on. It is said to remove the attractive charge from the pro-tected structure and render it virtually "invis:ble" to lightning. The system arrays combine a total of over 40,000 dissipating points to neutralize over 30,000 square feet of surrounding ground area.

For more information, contact Lightning Prevention Systems, 204B Cross Keys Rd., Berlin, N.J. 08009, (609) 767-7209; or circle #121 on the reader service card

ZERO IN ON MULTIPATHING

with Reader service Number 89.

SITCO CIRCULAR POLARIZED RECEIVE ANTENNAS ECCP & EMCP SERIES MSITCO Antennas

lO NINE Mr, 1.• R. • CYR 9,220 503 253 21.0)

COMMUNICATIONS TECHNOLOGY MAY 19E37 1 0

SYSTEM ECONOMY111111111111111111111111 1111111111 1111 11111111111111111

Practical considerations for rebuilds The need for additional channels continues to be a motivating force in the cable industry New services, the repositioning of basic, pay-per-view home shopping and soon, all force the operator to look for methods to add channels to existing systems. This article will attempt to review some of the important considerations involved in rebuild decisions.

By Patrick K. McDonough Corporate Chief Engineer. United Cable Televislon Corp

When to do a rebuild is just as important as how it should be done. The timing depends on a number of factors. Often this decision is made by default, as in the case of a franchise nearing expiration. Usually, some type of upgrade is re-quired to keep the franchise and to respond to competitive forces within a geographical area. Refranchise timing is tracked by most MSOs and, in conjunction with marketing, technical or revenue considerations, is the most common reason for rebuilding or upgrading a system. The need to refranchise is not the only reason

to consider upgrading a plant. Sometimes the opportunity for significant revenue increases will be recognized by a marketing group and the need for additional channels to accomplish this goal will be the decisive factor in the rebuild deci-sion. At other times, the ongoing costs to main-tain and operate an older plant will be motiva-tion to rebuild. Forces of nature, such as tor-nadoes or floods, also will bring on the need for rebuilds. The annual budget review is the logical time to consider most rebuild requirements within an MSO, since there usually is a concentration of management, marketing and technical per-sonnel gathered together who have both the ex-pertise and authority to make these decisions.

A myriad of possibilities

Once the decision has been made that a rebuild is necessary, the next step is to determine what exactly is required. This can be an area of confusion and conflicting demands for the engineer who is given this reponsibility. There are a myriad of possibilities to consider, and it must be stressed that there is no one right answer to the question of how to upgrade that will fit every circumstance. Up to this point the terms rebuild and upgrade

have been used interchangeably but a distinc-tion should be made. A rebuild, as used here, involves the total replacement of the existing cable plant. An upgrade, on the other hand, is the partial replacement of equipment and/or cable to extend the life or bandwidth of a system. Obviously the differences in cost between these two similar approaches are a significant part of the decision-making process. In practice the operator quite often will find that a combination

of both approaches is the best solution to any problems.

In making the decision to rebuild or upgrade. the engineer must consider a broad base of in-formation. One of the first and most important factors is why the need to rebuild exists in each particular case. If an 8-year-old plant needs to add six more channels for new services, this probably can be accomplished through some type of upgrade. If, on the other hand, a 15-year-old system built on the Pacific coast needs to add the same six channels, the system more likely will need to be rebuilt.

On-site inspection of the system is needed to resolve most of these questions. What is the con-dition of the cable and electronics? Can any of the existing gear be salvaged? Importantly, what is the condition of strand and other support hard-ware? Can this be reused? Is underground cable in conduit or direct buried? Can existing conduit, vaults and pedestals be used in the new plant? What is the condition of the drop wire and installa-tion passives and can they pass the new band-width? Significantly, this last question often is overlooked, even though it is of prime impor-tance. The answers to all of these and many more questions must be determined before final plan-ning can begin.

At this point it has been determined that a rebuild or upgrade is necessary and approx-imately what needs to be done. The next steps concern how the project will be completed. This is the nuts-and-bolts part of the process, the ac-tivities that most people associate with a rebuild.

First, accurate as-builts and/or strand maps of the existing system must be developed. As-built maps are required in an upgrade situation,

while good strand maps, with or without as-built information, are needed in rebuild projects. Maps should detail the information needed to deter-mine cable routing, include all M DU and future construction areas, show bridges, lakes and other obstructions, and indicate specifically any existing plant areas that can be included in the new system without modification. Design criteria and instructions should be

developed next. Some of this may have been completed in the analysis phase of the project but design now should be refined. This includes the call-out of system operating specifications, forward and reverse levels, bandwidth, and cable and passive device attenuations. Special instruc-tions, such as the need to maintain the same amplifier locations, also should be included. Mapping and design can and should begin well in advance of the actual construction effort. The design, whether done by phase or power supply area, should generate accurate BOMs (bill of materials) for project costing, material orders and project control.

'First, accurate as-builts and/or strand maps of the existing system must be developed'

Good contracts The next logical step will be deciding who does

the work, how they will be supervised, setting up reporting procedures and so on. A good con-tract, written by qualified attorneys, is a must. It should be specific in detailing the work functions, unit prices, time frames and responsibilities of all concerned parties. Items such as retainage, reports, payment for confirmed production, per-formance bonds and warranties should be included. Some MSOs have the capability of providing

such construction services from within the organization. On some projects, such as the drop-in upgrade of a smaller system, local system personnel may be able to handle the work themselves. A formal contract in these cases is not required, but care should be taken to make sure that system technicians receive the proper training prior to undertaking such a project. Whether a contractor is used or not, the crews

must be supervised by one person with overall responsibility for the project. The size of the con-struction management team will depend on the scope of the project. Construction management may vary from a single supervisor to a fairly large group consisting of various specialists such as make-ready engineers, underground locators, etc. Cost control, warehousing and materials handling should not be overlooked in determin-ing the construction team size. From this point on, it is a matter of relying on

the people put in place to bring the project to a successful conclusion. Naturally, the rebuild should be monitored via the reporting system to identify and correct problems before they become too serious. When the project is done, the entire system should be proofed just as a new-build plant would be. This is the final assurance that the newly rebuilt system will achieve the goals for which it was designed.

In summary, the steps taken toward imple-menting a rebuild or upgrade project should follow a logical pattern. Using when, what, how and who as a framework is the beginning of just such a logical approach. The better organized a project like this is, the more control the operator can have over the results. The end product will prove to be worth the effort.


THE THE

&,Ceiu\n't A MODERN CABLE FABLE

nce upon a time, in a not-so-far-off land, the grain the people used to make their

dai y bread was grown by four huge giants-and one small independent farmer. For years, all five grain producers co-existed peacefully, in an atmosphere of healthy competition.

But then one day, the four giants entered into a battle for control of the grain market. When the battle ended and the dust cleared, only two giants were left. And, of course, the little inde-pendent farmer.

wr hen a strange thing happened. Overnight, the competitive situation changed. And

the people began to worry "Now that there are only two giants:' one person said, "what's to stop them from charging higher prices for their grain?" "If they do, we won't be able to make as much bread as before cried another.

But the little farmer overheard the people talking. And he cleared his throat and took

a step forward. "My friends:' he said, "you're forgetting about me:' "You:' snorted a man at the front of the crowd, "what can you

do against such giants?" "I can do just what I've always done the farmer replied, "supply the finest grain and the best service in the land-at a very competitive price. As long as I'm around the giants carit take complete control of the grain industry-if you'll all think of me and include me in your business:'

e

T I here was a general chorus of "that's right:' • "we didn't think about the little farmer."

And so, after the farmer pledged to maintain his independence and to remain in the land for

111.'--; many years to come, the people went back to baking their bread, greatly relieved. And they all lived happily, and competitively, ever after.

rA ,a,l,hineorsntoerave,,., .thheustale aisrethat varfeiert3th&e cceonmspeteitrioilikne the

r cmfarmaine.tr, we atiCapscan, the only full service, independent C APSCAN al.caebuler autonomy. And

in d continue pUrevignoghtlillseebtoest

quality products and service in the business. We invite A Bu rnup & Sims Cable Products Group Company you to call us for a competitive bid on your next project.

See us at the NCTA Show. Booth 1642. Reeder Service Number 90.

PREVENTIVE MAINTENANCE111111111111111111111111111111111111111111

Building a system history By Peter Rumble Training Coordinator. McCaw Cableveon

Do unexplained subscriber complaints and mysterious outages have your service team run-ning aimlessly all over town "putting out fires?" Are some system amplifiers behaving like unru-ly brats, demanding your attention and throw-ing costly tantrums? Do portions of the plant seem to run flawlessly until the technician leaves the area or goes home at the end of the day? Are you wishing the cable system would leave you alone for just two minutes so you could get some work done?

If the answer to any of these questions is "yes," it's possible that you simply may be unaware of the plant conditions causing these headaches. A preventive maintenance program can bring some relief.

Creating and maintaining a system log can provide the technician with an indispensable troubleshooting tool. With adequate documen-tation, changes in plant conditions can be detected that otherwise would go unnoticed. Compiling information on selected plant parameters generates a history that, when reviewed, assists in identifying design oversights and construction errors.

System trunk data log

TRUNK AMP NO LOCATION

AMP TYPE AGC MGC PAD E0

PwR. IN OUT THRU SELF AC VOLTAGE XFORMER TAP

DC REG VOLT

CABLE SIZE/TYPE , IN OUT

CALCULATED INPUT AT DESIGN FREO, dBmV

SLM LEVELS DATE, TEMP •F ,

CHAN

IN

OUT

BRIDGER

FUSES Port 1- 2 3 4

SWEEP WIDTH ,_ MHz to MHz DATE TEMP °F

Insert Steep Picture Km*

. N Sokoifieonon, .R5 • I Pock to Wilily; N • Trunk Arno* from heaSend

110 MAY 1987

End-of-line check TEST LOCATiOft »0 *rue I» ITO

•Ico LIME LOGATCD 417

CUM

Z.

WC

'Cy»

VA V AV A VA VA V AV A V A 2 4

6 B

E

G

I 7

9 ! 1 i

13

J M ‘ P

R

7 W t

i

D t

LB HB LB HB LB NB ¡ LII 'HI LB NB LB HB LB HB LB NB C/D

%mu

i

NOTES

, s,... cnorod(4. SPoCCS 0.00vIOCD •••( roe COOOICIII IN TOE ACOOMILUT MAL / »AvlooT»)»oc 11•010 Wan CM 500 SUS -LOS C AAAAAAA 1.1 TO 7.10

T DC . SS ear• CARR, os •IN,

S LI • LOWOMOO ell • ITIONSOMO

• % Soy rococo»), OD SC »CCOoDE 0 oS •Cet ,0 SOAK VALUE


B.


1111111111111111111111111111111111111111111111

'Determine what records will be most useful to your operation and include them in your preventive maintenance program'

By periodically analyzing records of field equipment readings, trends and patterns can be spotted. Symptoms of plant deterioration often are exhibited as departures from the documented amplitudes of RF and AC signals, amplifier DC voltages and picture quality in-dicators like C/N (carrier-to-noise) and hum. The locations of faulty power supplies, corroded or loose coax connectors, cracked cable shields, improperly installed line corn ponents and other causes of picture degradation can be pinpointed by observing subtle changes in recorded data. Once identified, actions can betaken to repair

trouble spots before unplanned outages or subscriber complaints result. Plant rework can be scheduled on your own terms within reasonable time constraints and in favorable weather. This yields higher quality workmanship than can be obtained under the pressure of an outage during prime viewing hours.

Accurate records eliminate guesswork in trou-bleshooting. Documentation reduces errors that can result from relying on memory. Evidence is established that calculated design values were met, amplifier station configuration and type were verified, and desired frequency response was attained. This history can aid the sweep techni-cian in duplicating past response when equip-ment changes are made. The maintenance technician can benefit by consulting the log for specific AC voltage readings when troubleshooting powering problems.

Kinds of records Because no two cable systems are exactly

alike, you will need to determine what records will be most useful to your operation and include them in your preventive maintenance program. Additional logs might include histories on stand-by power supplies, battery maintenance, head-end equipment, tower lighting and specialized mini-systems for large commercial accounts like schools, motels and shopping centers. The system logs are intended to be permanent

records and therefore should not betaken to the field. A loose-leaf notebook will allow pages to be removed, copied for reference and replaced. A binder facilitates the addition of updated pages

Pre-Trained Employees Our Specialty

- -o-

Let Us Help Meet Your EEO Requirements

Quality Training With An Accent On Production And Safety

We Have The Best Beginning Level Employees To Fit Your Special Needs

If necessary we will travel to your system for cable marketing training and pole climbing certification.

Call Us For Custom Training Unicorn School Of Communication

55 Woodland Park Drive Kalispell, MT 59901

Kip Hayes— Owner/Instructor Phone: (406) 752-5487


and new data sheets for future builds. The logs should be established during the first proof of the cable system and updated whenever peri-odic balancing or response sweeping is per-formed on any trunk line.

At the front of each log, include a current copy of your preventive maintenance (PM) plan. It clearly should define: • The company's commitment to and philosophies on PM. • The limits of all plant parameters and technical specifications. • The frequency of data collection for each log. • Personnel accou ntable for reports and reviews of PM logs. • The procedures and test equipment required

for measurements. • The technicians currently qualified to perform the tests.

Establish a separate log book for each set of records. The system size and complexity usual-ly dictates the amount of material to be organ-ized and compiled. Headend test-point log

Product reliability and quality begin at the headend. Monitor the stability and performance of the headend and ensure the system input is optimum. For plant maintenance purposes, record the RF levels of each video and audio car-rier on the system and include a photo of the swept response as measured at the headend test point.


Sound engineering practices require that technicians responsible for trunk-line mainte-nance individually record these levels using the signal level meter assigned tothem for daily use. Meter serial number and date of measurement should be included as a permanent part of the log. If doubts about calibration, accuracy or stability arise, this reference can be used for comparisons.

Enter the values of AC voltages used in system powering, if applicable. Levels of test and data carriers, return signals and other inputs also should be included. System trunk data log

Document the actual field values listed for each trunk amplifier in the cable plant from the head-end to the end of the cascade. Recording the information essentially forces the technician to proof the system, amplifier by amplifier. Proper pad, equalizer, powering mode, voltages and operating levels are verified. Unnecessary bridger leg fuses are removed, the operation of AGC/ASC (automatic gain/slope control) circuitry is checked, and an examination of the station is made for mechanical integrity. Although not in the log, the conditions of straps, spacers, hard-ware, lashing wire, shrink boots and clearance should be noted and corrected, if possible. As

Superior signal intepity no added cost.

Amex connectom

Main nut

Integral \ RF shield


Center conductor Body gripping assembly

Lock nut

Patented field-focusing insulator

Long-life seals

Outer conductor gripping mechanism

Armex CATVFIVE pin type connectors feature a patented field focusing insulator that assures 42 dB minimum structural return loss from 0 to 500 MHz, a 20% improvement over most other designs. Result: less signal amplification will be required for a given length of cable run.

For information on the full line of advanced Annex Cable Connectors, write: Annex Cable Corporation, 2700 E. Nine Mile Road, Warren, MI 48091, or call (313) 755-2030.

AIRprOW CABLE TV emu_

HARDWARE

technicians work their way through to the end of the system, problems will be discovered and corrected. An invaluable system history will be generated in the process. The parameters included are considered as

the suggested minimum indicators of trunk sta-tion performance. Input/output channels selected should include system pilots, highest and lowest video carrier frequencies, one other carrier in each band and any other carriers of interest. A space is provided to attach the latest frequency response pictures, documenting that the desired peak-to-valley output has been at-tained for that station. Ideally, all trunk stations should be swept twice yearly, recorded and entered into the log.

Dedicate a section of the system log to each trunk line and identify each cascade using a numbering scheme or name describing its destination. As the completed data sheets are returned from the field, they are reviewed before entering into the log. Those items not meeting standards, or with disparities between calculated design and actual field values, can indicate potential field problems. These can be noted and looked at again later. Examples might include cable equalization problems, standing waves, at-tenuation discrepancies or borderline voltage readings. Although these conditions may not drastically affect picture quality, they must be cor-rected to ensure peak system performance and reliability. Trunk amplifier maintenance history The purpose of this record is to prevent

"repeated maintenance," that is, treating the symptoms and not the causes of signal problems over and over again. For example, it's possible for more than one technician to change a bridger module in the same location in a given week to correct a rash of complaint calls. Each was led to believe that the old module was the cause of the distortions in the feeder line, without the knowledge that it was replaced only hours ago. Yet each time it was exchanged, the problem cleared!

Technicians usually are too busy to discuss with one another the what, why, where and when of each module they change. By recording each problem and resolution for a particular amplifier location, the field technician or supervisor review-ing the log can see what has occurred. After repeated module changes, it should be evident that the amplifier was not causing the problem, but merely reproducing it. The informed techni-cian now can look for the real cause of the customer's poor reception.

File this record along with the corresponding system trunk data sheet for each amplifier sta-tion. This way, pages easily can be located and identified. Review work orders and maintenance reports daily as they return from the field, and make the proper log entries. End-of-line checks The end-of-line checks are used to monitor the

performance of the system on a "whole picture" approach. A new perspective on how the cable plant is operating is realized by weekly com-parisons of this record. Variations in headend stability, poor amplifier response, AGC failure and gradual increases in video distortions often can be detected only by reviewing this log.



At several test-point locations, video and audio carrier levels, C/N and hum are measured carefully and recorded. Ambient temperature also is rated, providing a reference for tracking proper AGC action. The RF carrier levels of every cable channel are not necessary for this check. Scrambled channels, system pilots, data streams, unmodulated test signals and other car-riers of interest in plant operation should be con-sidered. Regularly monitoring signal power level in the restricted bands verifies compliance with FCC limits. A check of picture quality with a known good

portable television set is recommended on every channel, if possible. As a backup, sweep response viewed at the end-of-line can detect spikes, suckouts, rolloffs and other abnormalities that might have developed since the last visit.

Finding and correcting the cause of an out-of-spec weekly reading on hum, for instance, could save your staff valuable time. Visiting three or four households, diagnosing the problem and then going out in the field to troubleshoot it is wasted effort.

Intermittent scrambling in just one part of town easily might be corrected. A search for the source of low RF levels at the end-of-line test point soon reveals a radial crack in the trunk line that

is located and repaired. The test points chosen for the end-of-line

checks will be used to monitor selected plant parameters. Establish several test points throughout the system on all major trunk lines. Include the ends of the longest cascades and the trunk lines feeding the areas of highest subscriber density. Also consider those portions of the town that routinely generate the majority of complaint calls. The number of test points is not as important

as the amount of coverage provided. Try to establish a minimum number that will provide an adequate representation of overall plant opera-tion. A good cross section, of course, will be dependent on plant miles, but five to15 locations can be logged weekly with little manpower. The accessibility of the test points is propor-

tional to the continued success of the program and the probability of obtaining reliable, accurate information on a regular basis. Data collection points located in backyard easements, on nar-row bridges or around heavily traveled highway intersections are to be avoided.

It will be necessary to assume that the bridger output is representative of the trunk that feeds it. At the trunk bridger location chosen, obtain test signals by either: A) Directional coupler or low-value tap cut into an unused bridger port. For accurate C/N measurements, it is desirable that at least 30 dBmV be available at the test point; or B) Subscriber tap-off points presently in the feeder line. This will provide adequate levels for all portions of the maintenance check except C/N in most systems. These readings will need to be taken where appropriate levels can be obtained.

Install a good quality drop wire from the signal source down the pole to a suitable height. The drop wire can be protected by installing it in PVC conduit or by covering it with pole moulding. Routing the drop close to existing pole mouldings or risers will maintain cosmetic ap-

Finally,AtLast Just InTimeí

5oo A"SEEI The need for another headend, dish, receivers and costly labor can be eliminated.

Install the Graycor Prolink in

less time than you could imagine saving thousands of

dollars. No FCC permit, no

easement permits to compli-cate your life. Capacity up

to 42 channels with

excellent carrier to noise at distances that will astound

you. The Graycor 500 was

chosen recently in a shoot-out against another

brand ( that resembles

a stove pipe) by one of the nation's major MSO's.

See the pmlink in action. Delivery is limited so inquire now at Midwest Corporation

operating since 1950

with a 1987

product line for

the future.

YOUR EXCLUSIVE PROLINK SOUTf,FAST DISTRIBUTOR

MIDWEST CORPORATION

CATV DIVISION

1-800-r64161 -V 0

pearances and minimize personnel climbing hazards. Guard against corrosion and possible RF leakage by "weatherizing" the connectors and providing a means to terminate the drop when not in use. The recommended frequency of data collec-

tion for the end-of-line check is weekly on all system test points. For scheduling purposes, stagger the readings so that all locations are not due the same day.

Why bother? Today's cable consumer demands the same

reliability and quality available from other home entertainment alternatives. Preventive maintenance can extend plant life, decrease replacement costs, increase operational efficien-

cy and be the determining factor in the monthly decision to renew service. The success of any PM program requires a

continuous commitment at every level of the organization. This knowledge must be understood in the corporate office as well as in the field. A lapse in dedication by any member of the team results in a loss of momentum. The program will falter and eventually may fail.

Resistance to PM programs will prompt responses like "we're too busy" or "we don't have the manpower." This indicates a situation in which the cable system is managing the staff. Implement a planned and organized program using a system of routine testing and accurate documentation to regain control of the plant and stay on top of it. Li

COMMUNICATIONS TECHNOLOGY MAY 19£37 113

CONSTRUCTION TECHNICDUES1111111111111111111111111111111

Salvageable revenues By Tom Wood Jr. Resource Recovery Systems

Lost revenue.. . a popular topic with any business interested in making a profit. Within the cable TV industry this subject lately has become synonymous with that of signal theft at the subscriber level. Unfortunately, another pertinent area of the industry, that of the system construc-tion phase, has been virtually ignored recently. Though perhaps not as glamorous a topic as

signal theft, there exists no other phase of a cable system's operation as potentially wasteful and costly as construction. Millions of dollars are spent on equipment and materials, the distribu-tion and utilization of which are essential to the very success of the system. Yet one routinely finds little or no coordination between the system's construction engineering personnel, its con-struction contractors and a reputable salvage contractor. This lack of preplanning usually

Scrap coaxial cable can be a good source of recyclable materials. Here, wreck-out is be-ing unloaded at a salvage contractor's facilities.

WHY CALL CABLE LINK? We can satisfy your needs, be it buying or selling, or

repairing your converters, line gear and headend equipment.

CABLE INK

/1/C.

WE'RE THE CABLE OPERATORS' CONVERTER STORE

AND A WHOLE LOT MORE!

Jerrold Oak Hamlin Eagle Texscan

OHIO 280 Cozzins Si. Columbus, OH 44213 1614f 221-.3131

Check our stock for your needs:

Pioneer RCA Scientific Atlanta Standard Component Arcom

Magnavox C-Cor Sylvania Blonder-Tongue

MICHIGAN Sales Ofti«• TEXAS Sales Office 2482 Tuson Drive - 21 Drayton Plains, MI 48020 131 b 671-0818

2439 NE Loop 410 - #140,1 San Antonio, TX 78217

630-3132

'In some parts of the country, landfills do not accept scrap reels and cable'

results in unexpected accumulations of partial reels of unusable coaxial cable as well as, in the case of rebuild systems, unwanted miles of wreck-out piled high at a headend or a contrac-tor's yard.

With landfill and dumpster fees soaring into the hundreds of dollars—not to mention rising labor costs—these accumulations of scrap can pose an expensive and time-consuming prob-lem to the MS0 as well as its contractors. Pro-per coordination between engineering, con-struction and purchasing can of course minimize some of these problems. Custom purchasing based upon the system's needs (if your largest aerial span is 1,600 feet, don't buy 2,200-foot reels of coax), as well as close supervision and control of the materials used, are essential. A cer-tain percentage of material, however, always will be unusable and should be disposed of in a cost-effective manner. The obvious solution is to sell these materials.

A system should plan in advance of construc-tion, however, to find a salvage contractor who will provide the best overall program to deal with reels as well as the cable and electronics. While there are a number of companies that will clean up your waste materials and haul them away, not all are prepared to pay for the privilege of doing so. This is particularly true when those firms are unaccustomed to the type and volume of scrap generated by a new or rebuild cable TV system.

Recyclable resources Scrap is made of critical natural resources

needed to build future systems. Landfills are not the place for these recyclable resources. In some parts of the country, landfills do not accept scrap reels and cable.

To ensure prompt and dependable services, as well as maximum dollar return, cable system operators only should deal with reputable recy-cling firms. This entails not only solicitation of the best scrap price but, more importantly, investiga-tion of the firm's past reputation within the in-dustry. A history of previous service with certain scrap contractors should be available between an MSC's corporate office and its various systems around the country. This is particularly useful when dealing with a nationwide recycling organization, of which there are few. A scrap contractor should be attuned to the

needs of his clients and even can help minimize waste. Accurate monitoring of incoming scrap payments can help pinpoint those areas where excessive and unacceptable percentages of scrap are being generated. The bottom line is that cable operators should be as concerned with their potential losses from system waste as from signal theft—both are lost revenue. El


Affordable Masterpiece

•

No specifications equal those of the Signal Vision Directional Tap It is, mechanically and electron-ically speaking, a work of art.

High art commands a high price, right? Wrong. The price for this tap is a value any critic would admire

So you don't have to be an art expert to make your own appraisal. The Signal Vision Directional Tap is nothing less than a masterpiece

Call Signal Vision for price and information about our new Directional Tap or for a catalog of our entire product line.

We Make The Connection Three Wrigley • Irvine, CA 92718

714 / 586-3196

2-WAY & 4-WAY OUT-PUT MULTI-TAPS

MODELS: SVT-20 SVT-40

Features:

True performance to 550 MHz and beyond • Machined brass F ports • Corrosion resistant 360 aluminum alloy housing and protective epoxy coating • Aluminum gasket for maximum RH integrity • Stainless steel spring loaded clutch • Tapered entry for center conductor • Neoprene weather-proof gasket. • Aerial or pedestal mounting without changing center seizure screws. • Center pin stop in seizure block. • Plastic PC board housing cover • Excellent insertion loss to 550 MHz.

Bandwidth:

Tap-to-Tap isolation:

Return loss:

Power passing:

5-550 MHz

30 db

20db minimum all ports

18db 5 MHz tap port

6 Amp ACiDC

Specifications:

Tap loss:

Impedance:

RFI:

Input/Output ports:

Subscriber ports:

1 db of assigned valu,

75 OHMS

—100 db

5/8 female

F-Type female (bras.


KEEPING TRACKI111111111111111111111111111111111111111111111111111111111111111111111

Coslo

Dennis Costo nas been named goduction manager at Broad-band Networks Inc. He will be responsible for the company's manufacturing operations. Before joining the company, Costo was

assistant vice president of manufacturing at Penn Tran Corp. Contact: P.O. Box 8071, State Col-lege. Pa. 16803 (814) 237-4073.

Stephen Hattrup has been named vice president and treas-

urer for American Television and Communications Corp Pr,or to

this, he was corporate vice presi-dent of financial planning.

Earl Langenberg and David Pangrac have been named direc-tors of engineering and technolo-gy. Prior to this, Langenberg was vice president of engineering for

Rogers Cablesystems. Pangrac previously was vice president of engineering for ATC's Kansas City Division

Also. Timothy Evard has been named director of marketing, strategy and planning. He previously was vice president of marketing for the Tampa Bay Divi-sion of Paragon Communications.

Finally, Raleigh Stelle III has been named standards engineer for ATC. Prior to this, he was vice president of marketing and a direc-tor for Texscan Corp. in Phoenix, Ariz. Contact: 160 Inverness Dr West, Englewood, Colo. 80112, (303) 799-1200.

Advanced Protection Tech-nologies announced Thomas Norling as vice president of research and development. His responsibilities include establish-

When you think of complete Service and Repair...

Think Com-Tek!

Sales • Refurbished Equipment

Hot Line • Headend Equipment • Test Equipment • Line Equipment • Converters

Repair • Work Guaranteed • Quick Turnaround • Headend Equipment • Test Equipment • Line Equipment

Two locations to serve you!

COM-TEK

24209 Clawiter Road Hayward, CA 94545

(415) 785-4790

1710 West 9th Street Sedalia, MO 65301

(816) 826-3011


116 MAY 1987

ing an electronic research facility for communications and power transmission protection. Norling previously held positions at ITT and General Cable Co. Contact: 14088 Icot Blvd., Clearwater, Fla. 33520. (813) 535-6339.

Zenith Electronics Corp. elected Robert Hansen to the new position of president of its Con-sumer Products Group. He will continue as a corporate executive vice president.

Howard Graham has been named corporate vice president of finance and chief financial officer at Zenith. He had been vice presi-dent of finance services since 1983.

Finally, John Taylor has been named director of corporate public relations and communications. Prior to this, he was Zenith's manager of this department. Con-tact: 1000 Milwaukee Ave., Glen-view, III. 60025. (312) 391-8181.

International Cablecasting Technologies appointed W. Thomas Oliver as its president and chief operating officer. He previously was senior vice presi-dent of Home Box Office. Contact: 9033 Wilshire Blvd., Penthouse, Beverly Hills, Calif. 90211, (213) 276-4660.

American Cablesystems of New York named Phil Ripa as its new director of engineering. Previously, he was project engineer for the MSO's Cam-bridge, Mass., system. Contact: 55 Tozer Rd., Beverly, Mass. 01915, (617) 921-0080.

Panasonic namec: Robert Chalfant planning manager of its Planning and Market Develop-ment Division. He will be respon-sible for coordinating efforts on behalf of Panasonic's parent com-pany, Matsushita Electric Corp. of America, to strengthen industrial sales in the United States. Previously. Chalfant was marketing manager for Panasonic's Cable Television Products Group. Con-tact: 1 Panasonic Way, Secaucus, N.J. 07094, (201) 348-7183.

Bob Holladay has been named director of marketing for CableBus Systems Corp. He will be respon-sible for all sales and marketing ac-tivities, as well as contributing to


Holladay

corporate planning and develop-ment. Prior to this, Holladay waz special projects manager for Delta Engineering. Contact: 7869 SW. Nimbus Ave., Beaverton, Ore. 97005, (503) 643-3329.

Signal Vision Inc. announced the appointment of Michael Soloman to the position of regional sales representative for the northern California, Washing-ton and Oregon territories. Prior to this, he was regional sales manager for RMS Electronics. Contact: 3 Wrigley, Irvine, Calif. 92718. (714) 586-3196.

G. Bickley Remmey has joined the Jerrold Division of General Instrument Corp. as manager of sales support/ad-ministration. Prior to this, he was Northeast regional sales manager for Texscan Corp. Contact: 2200 Byberry Rd., Hatboro, Pa. 19040, (215) 674-4800.

Ward

Brian Ward has been ap-pointed director of marketing for Triple Crown Electronics. Prior to this, he was sales manager for Electrohome Electronics. Contact: 4560 Fieldgate Dr., Mississauga, Ontario L4W 3W6 Canada, (416) 629-1111.

4

I.

TECH BOOK1111111111111111111111111111111111111111111111111111111111111111111

0

CATV applications of Ohm's law

e

I

.

0(

o

o

By Ron Hranac and Bruce Catter Jones lntercable Inc.

The relationship between voltage, current and resistance is known as Ohm's law. The current flowing in a circuit is directly proportional to the applied voltage and inversely proportional to the resistance, which is shown by the mathematical formula

E I= R

The following diagram illustrates conversions between common units of electrical measure-ment as they relate to Ohm's law.

Ohm's law

E = Voltage I = Current R = Resistance W = Power

COMMUNICATIONS TECHNOLOGY MAY 1987

Example 1

Problem: How much current (I) is flowing through the following circuit?

_L E = 24 VDC =

= ?

Unknown: Current (I)

From the chart: I = E

= 24 I 12

I = 2 amps

Example 2

Problem: What is the value of the resistor in the following circuit?

E = 30 VDC = ? I = 2 amps

Unknown: Resistance (R)

From the chart: R = E

R = 30 2

R = 15 ohms

Example 3

Problem: 1) What is the voltage drop in the span of cable shown below? 2) What is the AC voltage at amplifier B?

E = ?

60 V power supply

Loop resistance (R) = 2.6 (,.2

Unknown: Voltage (E) drop in cable

1) From the chart: E = IR

E = (1.5)(2.6)

E = 3.9 VAC

2) AC voltage at amp B = 60 V — 3.9 V

= 56.1 VAC

Current (I) draw = 1.5 amps

E — ?

MAY 1987 COMMUNICATIONS TECHNOLOGY

Enhance your drop cable invest-ment by specifying the exclusive lifeTime- cable from Times Fiber Communications. For as little as an additional 18< per subscriber*, lifeTime can "insure" maximum protection and offer 20-30% longer cable life.

lifeTime provides increased cover-age against moisture—one of the major causes of premature cable failure, signal leakage and damag-ing corrosion. Let your customers become the beneficiaries of clear reception, decreased incidence of flashing and reduced subscriber outages.

lifeTime cable diminishes the need for expensive sealed con-nectors. Decreased frequency of connector replacement and the connector compatibility of this cable should dramatically reduce labor and maintenance costs.

Center Conductor

First Outer

Conductor •

Second Outer

Conductor

Dielectric

j--lifeTime Protectant

Jacket

Your most significant operating expense between the tap and the home is labor, not material. By specifying lifeTime drop cable, you can defer the labor costs, drop replacement and increase operating profits. Make lifeTime a part of your quality picture.

For a free benefit analysis contact: Times Fiber Communications, Inc. P.O. Box 384, Wallingford, CT 06492, (203) 265-8540 or 1-800-TFC-CATV. *Average drop length 125 feet • lifeTime is not recommended for indoor applications

11" FC TIMES FIBER COMMUNICATIONS. INC. an

eY)2company

358 Hall Ave • P 0 Box 384 • Wallingford. CT 06492

ir-FC ... Where technology meets the bottom line. See us at the NCTA Show, Booth 2148.


CALENDAR 111111111111111111111111111111111111111111111111111111111111111111111111111111111111I

May

May 4-6: Canadian Cable Show, Convention Center, Montreal, Canada. Contact (613) 232-2631. May 12-14: Maryland/Delaware/ D.C. Cable Television Associa-tion annual spring meeting, An-napolis Hotel, Annapolis, Md. Con-tact Susan Hollis, (301) 268-2721. May 14: SCTE Central Indiana Meeting Group seminar on BCT/E Category IV-Distribution Systems, Indianapolis Motor Speedway, Indianapolis. Contact Rick Cole, (317) 841-3692. May 17-20: NCTA Show, Conven-tion Center, Las Vegas. Contact (202) 775-3550. May 18-21: Trellis Communica-tions seminar on designing and installing fiber-optic networks, Trellis Training Center, Salem, N.H. Contact (603) 898-3434. May 26: SCTE Satellite Tele-Seminar Program, "RF Field Strength Measurement Principles and Practices," 12-1 p.m. ET on Transponder 7 of Satcom I II R. Con-tact (215) 363-6888.

June

June 1-5: Information Gate-keepers' European Fiber Optic Communications and Local Area Networks Exposition, European World Trade and Convention Center, Basel, Switzerland. Con-tact Renee Farrington, (617) 232-3111. June 2-4: Online International's CableSat 87 exhibition and con-ference, Metropole Hotel, Brighton, England. Contact Pam Howard, 01-868-4466. June 3: SCTE Rocky Mountain Chapter review on Category IV-Distribution Systems and BCT/E testing. Contact Joe Thomas, (303) 978-9770. June 7-9: Space and Telecomm Inc.'s annual symposium, Albert Thomas Convention Center, Houston. Contact (713) 225-1950. June 10-12: Institute for Ad-vanced Technology seminar on local area networks, IAT Training Center, Washington, D.C. Contact (800) 638-6590. June 15-17: Northeast Cable

Planning ahead July 20-22: New England Show, Dunfey's Hyannis Hotel, Hyannis, Mass. Aug. 30-Sept. 1: Eastern Show, Merchandise Mart, Atlanta. Sept. 21-23: Great Lakes Expo, Indianapolis Conven-tion Center/ Hoosier Dome, Indianapolis. Oct. 6-8: Atlantic Show, Convention Center, Atlantic City, N.J. Oct. 18-22: Mid-America CATV Show, Hyatt Regency at Crown Center, Kansas City, Mo. Dec. 14-16: Western Show, Convention Center, Ana-heim, Calif.

Television technical seminar, Roaring Brook Ranch Resort, Lake George, N.Y. Contact Bob Levy, (518) 474-1324. June 15-17: Online Interna-tional's Localnet East exhibition

and conference, Hilton Hotel, New York. Contact Carol Peters, (212) 279-8890. June 15-19: Information Gate-keepers' ISDN/Broadband Net-works for the Future, Merchandise Mart and Westin Peachtree Plaza, Atlanta. Contact Renee Farrington, (617) 232-3111. June 16-18: Jerrold technical seminar on applying problem-solving technology, Chicago. Con-tact Jerry McGlinchey, (215) 674-4800. June 19: SCTE Heart of America Meeting Group seminar on BCT/E Category II—Video and Audio Signals and Systems, Holi-day Inn Sports Complex, Kansas City, Mo. Contact Wendell Woody, (816) 474-4289. June 22-25: Trellis Communica-tions seminar on designing and installing fiber-optic networks, Trellis Training Center, Salem, N. H. Contact (603) 898-3434. June 23-25: C-COR Electronics technical seminar, St. Louis. Con-tact Tammy Kauffman, (800) 233-2267 or (814) 238-2461.

• e're preparing for our first anniversary,

here at JGL Electronics, and we want you to join our celebration. Our reliable

service, quick turnaround, and competitive prices have made this an exciting and successful first year.

So let's celebrate! To our customers who helped • make this first year a success we're sending two coupons worth $50 each toward their next two repairs. And if you're not our customer yet, try us, and we'll send you two $50 coupons for your second and third repair orders. •

• For additional information call, write, or simply circle the reader service number below. Don't wait — let's celebrate!

Repair & Calibration Specialists for Cable Test Equipment

JGL ELECTRONICS, INC.

RO. BOX 256 252 SOUTH THIRD AVENUE BEECH GROVE, INDIANA 46107 317/7E13-6130

IRWIN INDUSTRIES INC. "Committed To Service Excellence."

III

III

III

Customer Installations

Multiple Dwelling Units

Plant Construction and Maintenance

Long Beach, California (213) 595-4747



AD INDEX 11111111111111111 1111111

Alpha Electronics 36

Alpha Technologies 77

AM Cable 31

American Cablesystems of Florida 84

Anixter 124

Antenna Technology Corp. 105

Armex 112

Brad Cable Electronics Inc. 71, 73, 75

Broadband Engineering 51

Burnup & Sims 9, 109

Cable Link 114

Cable Security Systems Inc 6

Cable Services 2

CableTek Center Products 90

CADCO 88

CaLan 123

CATV Services Inc. 28, 98

C-COR Electronics 34-35

Channelmatic 97

Comm/Scope 56, 69

ComSonics 15, 83

ComTek 116

Converter Parts Inc 95

Eagle Comtronics 36, 37

Eastern Cable Television Services Inc 10

English Enterprizes 95

EZ Trench 74

FM Systems 10

General Electric 89

General Instrument/TOCOM Division 47

Groundhog Inc. 12

GNB Batteries 25

Head End Co. 21

IFR 55

Intercept Communication Products 14

Intrastellar Electronics 95

Irwin Industries 120

ISS Engineering 99

ITW Linx 103

Jensen Tools 12

Jerrold/General Instrument 5

JGL Electronics 120

Jones Futurex 84

Lakeshore Cable Construction 32

Lanca Instruments Inc. 93

Larson Electronics 95

Leaming Industries 82

Lightning Deterrent Corp. 93

Lindsay Specialty Products 20

1111111 11111111111 1111111111111111111111111111111

LAC 24

M/A-COM/Mac 19

Magnavox 13

Main Line Equipment 16

M&B Sales 24

Michigan State University 80

Microflect 80

Midwest Corp. 113

Monroe Electronics Inc. 70

Multi Link 28

Nacom Construction Corp. 76

Northeast Filter 102

Oak Communications 11

Panasonic Industrial Co. 33

Passive Devices 95

Pico Macom 23

Pioneer Communications of America 27

Precise Manufacturing 17

Progressive Electronics Inc. 30

PTS/Katek 81

Ointar 49

OAF Services 91

Resource Recovery System Inc 44

RF Analysts 8

Riser-Bond/Western CATV 98

RMS Engineering 100

Rycom Instruments Inc. 103

Sachs Communications Inc. 103

SCTE 87

Scientific-Atlanta 7

Sencore Inc. 29

Signal Vision 115

Sitco Antennas 107

Standard Communications 41

Stelco Inc. 101

Temtron Electronics Ltd. 21, 44

Three Dimensional Artworks Inc. 95

Time Manufacturing 90

Times Fiber 119

Toner Cable Equipment 43

Trilogy Communications 3

Triple Crown 54

Trompeter 21

Unicorn 111

Video Tape Systems 48

Viewsonics 45

Wadena Vocational Technical Institute 95

Wavetek Indiana 53

Wegener Communications Inc 79

COMMUNICATIONS TECHNOLOGY MAY 1987 '121

CICIORA'S FORUM

Competing for quality By Walter S. Ciciora, Ph.D. Vice President of Strategy and Planning American Television and Communications Corp

Cable technologists long have appreciated the strategic importance of signal quality; it always has been a part of good service. Now as we become more attuned to competition, signal quality takes on even greater importance—a strategic importance. There are a number of aspects to signal quality.

We can argue for hours over subtle differences between images. But one thing that defies argu-ment is an outage. Outage control is the "necessary but not sufficient" fundamental con-dition for good signal quality. Once we have outages under control, we can turn our attention to the other aspects of signal quality. Human perception has difficulty with absolute

judgments of video quality. An isolated TV receiver's picture can be acceptable even when it is badly out of adjustment. But relative com-parisons are remarkably easy. Even subtle dif-ferences are noticeable when many screens are side by side. Color differences between TV receivers are striking when viewed on the showroom floor of a TV dealer. Yet almost any one of the sets seen by itself would be accepta-ble. So an important principle is that we must be very careful of situations in which the subscriber might be able to make comparisons. There are three types of comparisons to be

concerned about: 1) time-sequenced, 2) side-by-side and 3) to other images. Time-sequenced comparisons are the ones most likely to happen in the home, while side-by-side are salesroom floor situations. Comparisons to other images are the least likely evaluations made by subscribers. Video professionals can be expected to use 35mm film or movie theater images as standards.

The A/B switch Consider some of the ways in which cable

subscribers may have an opportunity for com-parisons in time sequence. A current hot topic involves A/B switches. If subscribers use an A/B switch to choose between off-air and cable reception, it is important that they not experience noticeably poorer signal quality on cable. The greatest vulnerabilities occur where the off-air signals are strong and ghost-free. (A ghost is a delayed and transformed version of the original image.) Cable signals likewise must be noise-and ghost-free. There is an unfortunate vulnerability with off-

air comparisons. If the off-air signals are very strong and the TV receiver's immunity to direct pick-up (DPU) is inadequate, cable performance

may appear to be inferior when, in fact, it is the TV receiver's fault. DPU is the susceptibility to interfering signals directly picked up off-air by the receiver's internal circuits because of inadequate shielding. Where local signals are carried "on channel," this interference appears on the screen as leaving ghosted images. In cable systems operating on a harmonically related carrier (HRC) frequency plan, annoying beats between the broadcast carrier and the cable signal car-rier result in diagonal bars in the picture. A solu-tion is to add a converter. But this has negative consumer electronics interface consequences. An extremely damaging situation occurs when

we invite a comparison by having an outage. If subscribers see a better picture when they switch to the external antenna, we have shot ourselves in the foot. Subscribers, already irritated over the outage, just may be pushed over the edge, resulting in the loss of subscriptions. The best opportunity to shine is when the off-

air signals are inferior. Good antennas, even ghost-canceling configurations of antennas, can ensure a quality picture at the headend. Good cable practice can deliver it to the home. It would be a mistake not to take advantage of such op-portunities to do better than the alternative. A bothersome side-by-side comparison in-

volves direct broadcast satellite (DBS). The nature of the DBS signal is that it is free of ghosts and very likely to be free of cross modulation products. It is an FM signal, unlike cable's AM. Signal-to-noise can be controlled by the size of the dish and the quaky of the low-noise converter. A point of vulnerability is the showroom floor of the TVRO dealer. With a cable feed and a signal from a large dish, the dealer can make com-parisons that can be slanted in the TVRO's favor. This also can cost cable a lost subscription. It is important to ensure that cable headend satellite signals are of first quality. Modern consumer-grade TVROs have the potential to produce bet-ter pictures than old earth stations that have been maintained poorly. The most troublesome situation involves the

VCR. The number of cable subscribers exposed to this comparison far exceeds any other. When subscribers rent videotapes, they sometimes ex-perience "better video." The nature of the "bet-ter" carries important messages for cable prac-tice. Present rental videotapes actually have less resolution than broadcast or cable video. Their signal-to-random-noise ratio is not all that dif-ferent from cable or broadcast video. But they have very little coherent interference. Coherent interference on cable results in identifiable im-ages or patterns in the picture. The interference

If subscribers see a better picture when they switch to the external antenna, we have shot ourselves in the foot'

may be a ghost picked up by the headend antenna. Another alternative is co-channel interference,

the simultaneous reception of two different video images. Cross modulation overlays an image from another channel on the viewed image. Sometimes all that can be recognized from the other channel is the vertical and horizontal blank-ing bars slowly rolling through the desired image.

Finally, there is a wide range of beats resulting in non-image patterns on the screen: diagonal bars, herringbone patterns or just the ap-pearance of looking at the TV receiver through a screen door. None of these are present in the rental tape, which is popped into the VCR for Fri-day night viewing. The really bad news about VCRs is that "you

ain't seen nothing yet." "Super VHS" is about to make its appearance in the United States. It will put video on the subscriber's screen that will "knock your socks off." But that's a subject for next month's column. See you then. Eità


CALAN's Lightweight Champion. The Heavyweight Performer.

Weighing in at only 20 pounds, the CALAN Inc. Model 1776 Integrated Sweep Receiver replaces over 60 pounds of traditional field test equipment.

With a 5-600 MHz totally usable sweep range available, and a completely non-interfering sweep operation, system sweep now becomes an easy-to-carry maintenance tool.

VCRs, addressable converters, and data transmission are completely unaffected, as the Model 1777 Integrated Sweep Transmitter sets automatic guard bands around the carriers on the system, protect-ing them from damage.

This means that 550 MHz systems, or ANY system concerned about sweep interference, now has one less worry.

G o.

kl21.31eLL:Lbkl-LILL • ‘, ‘, I

20 POUNDS And to make routine maintenance even lighter. a 5-600 MHz digital Spectrum Analyzer is built into the unit, for a complete Proof-of-Performance capability anywhere in the system... including CTB, Carrier-to-Noise Levels, and Radiation Measurements.

Perhaps the most significant weight difference is that the Model 1776/1777 costs OVER 30% LESS than a comparable package!

• •

If this combination of a non-interfering sweep and spectrum analyzer that weighs 2/3 less and Costs V3 less sounds like the perfect solution to your maintenance prob-lems, maybe it's time you called to arrange for a demonstration in your system.

Heavyweight performers don't HAVE to be heavyweights.

N CABLE AND LOCAL AREA NETWORKS CALAN INC. R.R. 1. BOX 861' DINGMANS FERRY, PENNSYLVANIA 18328 (717) 828-2356



Now Anixter puts CommiScopé/ Coaxial Cable even closer to

your next rebuild!

...That's because we've added additional stock to all of our on-line computer linked distribution centers located throughout North America.

Anixter has a "just-in-time" delivery service that puts your rebuild trunk, distribution and drop cable at the job site where and when you need it. So don't buy more cable for rebuilds than you need.

Remember, at Anixter, Service is our Technology.'

ANIKIR COMMUNICATIONS

WEST-ANAHEIM: (714) 778-4414. (800) 854-0443. ANCHORAGE: (907) 274-8525: DENVER: (303) 373-9200, (800) 841-1531: SEATTLE: (206) 251-6760. (800) 426-7665; MIDWEST-CHICAGO: (312) 364-7000. (800) 544-5368; DALLAS: (214) 484-2933, (800) 231-5006: SKOKIE, IL HDOTRS: (312) 677-2600: EAST-ATLANTA: (404) 449-6533, (800) 241-5790: CIN-CINNATI: (513) 733-9100. (800) 543-0113: NEW JERSEY: (201) 328-0980. (800) 631-9603: ROCHESTER: (716) 426-3440. (800) 252-7516: TAMPA: (813) 626-7115. (800) 237-6466; CANADA-CALGARY: (403) 250-9646. MONTREAL: (514) 636-3636: TORONTO: (416) 625-5110: VANCOUVER: (604) 321-5885.

In an emergency. weekends and holidays or alter 5 PM call toll free 118001 323-8167 CORPORATE OFFICES, ANIXTEFi BROS INC. 4711 Golf Road. Skokie. IL 60076.1312) 677-2600

•

Mail To:

iintriEt

DEPT. COMM/SCOPE 4711 Golf Rd , Skokie, IL 60076

Please send me more information on Comm/Scope's coaxial cable

Name _

Title _

Company

Address

City

Telephone

-Comm/Scope is a division of General Instrument 1987 Anixter Bros . Inc

CT 5/87


Documents

worldradiohistory.com...Head-end through drop materials, it performs the way we say, or we'll correct it — immediately. Satisfaction guaranteed. - • Head-end Moll** ,* In • •