TMS-3000 CELP VOICE CHANNEL MODULE - GDC · OVERVIEW The CELP (Codebook Excited Linear Predictive) Voice Channel Module is an analog voice channel card for the TMS-3000, TMS Compact,

Publication No. 036R480-000Issue 6, January 1995

OPERATING AND INSTALLATION INSTRUCTIONSFOR

TMS-3000CELP VOICE CHANNEL

MODULE

General DataComm, Inc.MIDDLEBURY, CONNECTICUT06762-1299

ATTENTION!STATIC SENSITIVE DEVICES

PROPER HANDLING AND GROUNDINGPRECAUTIONS REQUIRED

This equipment contains electrostatic sensitive devices. Use ESD precautionaryprocedures when removing or inserting parts or printed circuit (pc) cards. Keep partsand pc cards in their antistatic packaging material until ready to install.

The use of an antistatic wrist strap, connected to the grounded equipment frame orchassis, is recommended when handling pc cards during installation, removal, orsetting of on-board option switches. Do not use a conductive tool, such as a screwdriveror paper clip, to set the position of the option switches.

INSTALLATION SAFETY INSTRUCTIONS

a. Never install telephone wiring during a lightning storm.

b. Never install telephone jacks in a wet location unless the jack is specificallydesigned for wet locations.

c. Never touch uninsulated telephone wires or terminals unless the telephone line hasbeen disconnected at the network interface.

d. Use caution when installing or modifying telephone lines.

CAUTIONPotentially hazardous voltages exist within this unit.

TMS-3000CELP VOICE CHANNEL

MODULE(GDC PART NOs. 036M285-001 through -005)

General DataComm, Inc. (GDC)Middlebury, Connecticut 06762-1299

This product was designed and manufactured by

WARNING

This equipment has been tested and found to comply with the limits for a Class Adigital device , pursuant to Part 15 of the FCC rules. These limits are designed toprovide reasonable protection against harmful interference when the equipment isoperated in a commercial environment. This equipment generates, uses and canradiate radio frequency energy and, if not installed and used in accordance withthe instruction manual, may cause harmful interference to radio communica -tions. Operation of this equipment in a residential area is likely to cause harmfulinterference, in which case the user will be required to correct the interference athis own expense.

The user is cautioned that any changes or modifications not expressly approvedby the party responsible for compliance would void the user's authority to operatethe equipment.

CRC-REQUIRED NOTIFICATION

This equipment is a Class A digital apparatus which complies with the RadioInterference Regulations, CRC c.1374.

PUBLICATION NOTICE

This manual has been carefully compiled and checked for accuracy. The infor-mation in this manual does not constitute a warranty of performance. Further-more, GDC reserves the right to revise this publication and make changes fromtime to time in the content thereof. GDC assumes no liability for losses incurredas a result of out-of-date or incorrect information contained in this manual.

The features described herein may not exist on all versions of the software andare subject to change without notice.

READER’S COMMENTS

Comments regarding this manual should be addressed to:

Publications DepartmentGeneral DataComm, Inc.1579 Straits TurnpikeP.O Box 1299Middlebury, CT 06762-1299

PROPRIETARY NOTICE

This publication contains information proprietary and confidential to GeneralDataComm, Inc. Any reproduction, disclosure, or use of this publication isexpressly prohibited except as General DataComm, Inc., may otherwise authorizein writing.

Copyright, General DataComm, Inc., 1995

FCC-REQUIRED NOTIFICATION

FOR USERS OF FCC-REGISTERED EQUIPMENT

Read before using this technical manual or installing subject equipment.

This equipment complies with Part 68 of the Federal Communications Commission (FCC) Rules andRegulations. Connection of data communication equipment to the public telephone network isregulated by the FCC Rules and Regulations. These regulations require:

A. All connections to the telephone network must be made through standard plugs and telephonecompany provided jacks or equivalent.

B. Connection of this equipment to party lines and coin telephones is prohibited.

C. If the telephone company asks you what equipment is connected to the telephone line, tell them towhich line the equipment is connected, and give them the FCC Registration number and RingerEquivalence number of the equipment. These numbers can be found on a label located on the backof the front panel on all DataComm-type equipment and on the underside or rear panel of otherequipment.

D. If you experience trouble, disconnect the equipment from the telephone line to determine if theequipment is malfunctioning. If it is, remain disconnected until the problem is corrected. Shouldthis equipment cause harm to the telephone network, the telephone company may discontinue yourservice temporarily. If possible they will notify you in advance. But if advance notice is notpractical, you will be notified as soon as possible. You will be informed of your right to file acomplaint with the FCC.

E. The telephone company may change its communication facilities, equipment, operations, andprocedures where reasonably required for operation. If this occurs, the telephone company willnotify you in writing.

F. It is the user's obligation to notify the telephone company prior to disconnecting equipment from1.544 Mbps digital service.

G. According to Part 68 of the FCC Rules and Regulations, customers are not authorized to repair ormodify this equipment. Any repair or modification will null and void the FCC registration andthe warranty of this equipment.

Rev. 4, October 1986

CANADIAN DEPARTMENT OF COMMUNICATIONS (DOC) REQUIRED NOTIFICATION

FOR USERS OF DOC-CERTIFIED EQUIPMENT

Read before using this technical manual or installing subject equipment.

The Canadian Department of Communications label identifies certified equipment. This certificationmeans that the equipment meets certain telecommunications network protective, operational, andsafety requirements. The Department does not guarantee the equipment will operate to the user'ssatisfaction.

Before installing this equipment, users should ensure that it is permissible to be connected to thefacilities of the local telecommunications company. The equipment must also be installed using anacceptable method of connection. In some cases, the company's inside wiring associated with a singleline individual service may be extended by means of a certified connector assembly (telephoneextension cord). The customer should be aware that compliance with the above conditions may notprevent degradation of service in some situations.

Repairs to certified equipment should be made by an authorized Canadian maintenance facilitydesignated by the supplier. Any repairs or alterations made by the user to this equipment, or equipmentmalfunctions, may give the telecommunications company cause to request the user to disconnect theequipment.

Users should ensure for their own protection that the electrical ground connections of the power utility,telephone lines, and internal metallic water pipe system, if present, are connected together. Thisprecaution may be particularly important in rural areas.

Caution: Users should not attempt to make such connections themselves, but should contact theappropriate electric inspection authority, or electrician, as appropriate.

CANADIAN EMISSIONS REQUIREMENTS

“This digital apparatus does not exceed the (ClassA) limits for radio noise emissions fromdigital apparatus set out in the Radio Interference Regulations of the Canadian Department ofCommunications.”

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Publications DepartmentTechnology CenterGeneral DataComm Industries, Inc.Middlebury, Ct 06762-1299

i

TABLE OF CONTENTS

Section &Subject Page

1 — INTRODUCTION

OVERVIEW ................................................................ ................................................................................. 1-1

FUNCTIONAL DESCRIPTION ................................................................ .................................................. 1-1

FUNCTION OF THE TMS/SUPERVISORY CONTROLLER................................................................ .... 1-2

TECHNICAL MANUALS ................................................................ ............................................................ 1-2

EQUIPMENT LIST................................................................ ...................................................................... 1-3

SERVICE AND TRAINING ................................................................ ........................................................ 1-3

APPLICATIONS ................................................................ .......................................................................... 1-3

2 — INSTALLATION

UNPACKING AND HANDLING ................................................................ ................................................ 2-1

INSTALLATION PROCEDURES................................................................ ................................................ 2-1

PREOPERATIONAL CHECK ................................................................ ..................................................... 2-1

OPTION SELECTION ................................................................ ................................................................. 2-1

MOUNTING OF CELP VOICE CHANNEL MODULE ................................................................ ............... 2-4

CELP VOICE CHANNEL SIGNALING ................................................................ ..................................... 2-5

E-Lead Signaling State ................................................................ .............................................................. 2-6

E-Lead Polarity................................................................ .......................................................................... 2-6

Noise Suppression Filter ................................................................ ........................................................... 2-7

In-Band E&M Signaling ................................................................ .......................................................... 2-7

E-Lead Loss of Sync................................................................ ................................................................... 2-8

CELP Module Analog Levels ................................................................ .................................................... 2-9

Analog Input Fine Level Adjustments................................................................ ...................................... 2-10

Echo Canceller ................................................................ ........................................................................... 2-11

3 — OPERATION

OVERVIEW ................................................................ ................................................................................. 3-1

CONTROLS, INDICATORS AND CONNECTORS ................................................................ .................... 3-1

4 — PRINCIPLES OF OPERATION

OVERVIEW ................................................................ ................................................................................. 4-1

Base Card Operation ................................................................ .................................................................. 4-1

E&M Signaling (-001 Version) ................................................................ ................................................. 4-1

E&M Signaling (-002, -003, -004, -005 Versions) ................................................................ ....................... 4-2

Piggyback Card Operation ................................................................ ........................................................ 4-2

5 — TESTS

OVERVIEW ................................................................ ................................................................................. 5-1

ii

TABLE OF CONTENTS (Cont.)

Section &Subject Page

5 — TESTS (Cont.)

DATA PATH TESTS................................................................ ................................................................... 5-1

Digital Test ................................................................ ................................................................................ 5-1

Control State Test ................................................................ ....................................................................... 5-1

User Data Test ................................................................ ........................................................................... 5-1

1 kHz Tone Test ................................................................ ........................................................................ 5-1

SET dB LEVEL ADJUSTMENT................................................................ .................................................. 5-2

TEST POINTS ................................................................ ............................................................................. 5-2

TECHNICAL ASSISTANCE PROCEDURE ................................................................ ................................ 5-2

TRAINING ................................................................ .................................................................................. 5-3

APPENDIX A — TECHNICAL CHARACTERISTICS

APPENDIX B — CELP VOICE CHANNEL MODULE APPLICATIONS

APPENDIX C — M-LEAD SIGNALING INTERFACES

APPENDIX D — CELP CIRCUIT VOICE LEVEL TESTING

APPENDIX E — CELP VOICE CHANNEL MODULE CONNECTOR PIN ASSIGNMENTS

APPENDIX F — GLOSSARY

INDEX

LIST OF ILLUSTRATIONS

Section &Figure Page

2 — INSTALLATION

2-1 CELP VOICE CHANNEL MODULE OPTION LOCATIONS........................................................... 2-3

3 — OPERATION

3-1 CELP VOICE CHANNEL MODULE FRONT PANEL ................................................................ ... 3-2

LIST OF TABLES

Section &Tables Page

1 — INTRODUCTION

1-1 EQUIPMENT LIST................................................................ ........................................................... 1-3

1-2 FEATURE LIST ................................................................ ................................................................ 1-3

iii

LIST OF TABLES (Cont.)

Section &Tables Page

2 — INSTALLATION

2-1 CELP PLUG-IN OPTION, SIGNALING TYPE................................................................ ............... 2-2

2-2 VOICE CHANNEL CONNECTION CABLES ................................................................ .................. 2-4

2-3 OPTION SELECTIONS, M-SIGNALING TYPES................................................................ ............. 2-5

2-4 OPTION SELECTIONS, E-LEAD SIGNALING STATE ................................................................ .. 2-6

2-5 OPTION SELECTIONS, E-LEAD POLARITY ................................................................ ................ 2-6

2-6 OPTION SELECTIONS, NOISE SUPPRESSION FILTER .............................................................. 2-7

2-7 OPTION SELECTIONS, IN-BAND E&M SIGNALING................................................................ ... 2-7

2-8 OPTION SELECTION, E-LEAD CONDITION UPON LOSS OF SYNC ......................................... 2-8

2-9 OPTION SELECTION, INPUT/OUTPUT LEVELS................................................................ ......... 2-9

2-10 OPTION SELECTIONS, INPUT LEVEL ADJUSTMENT ............................................................... 2-10

2-11 OPTION SELECTIONS, CODEC TIMING ................................................................ ...................... 2-11

SECTION 1

INTRODUCTION

OVERVIEW The CELP (Codebook Excited Linear Predictive) Voice Channel Moduleis an analog voice channel card for the TMS-3000, TMS Compact, Univ.MM+ V4 TDM and the MINIMUX TDM. The CELP module providesvoice encoding algorithms that maximize voice channel bandwidthutilization while offering low bit rate values of 4.8 and 6.4 kHz. A CELPmodule in a TMS-3000 also offers a bit rate of 9.6 kHz. OCM CELP iscovered in GDC Publication 036R340-000.

The CELP Voice Channel Module is used in transmission applications tomaximize available bandwidth. Applications include use in digital ser-vices such as ASDS (FT-1), ADN, satellite and in feeder applications inwhich a customer needs to integrate both voice and data. Voice communi-cation is two-way simultaneous (full duplex).

FUNCTIONALDESCRIPTION

The CELP Voice Channel Module consists of two cards; a base card and apiggyback card. Voice is first processed by an analog-to-digital conver-sion on the base card yielding a 64 kHz data rate. This data is then con-verted to a low bit channel rate through software on the piggyback card.The bit rate is 4.8, 6.4 or 9.6 kHz. An echo canceller feature is providedfor large inherent delays involved in the digital signal processing of thevoice channel.

2-state in-band E&M signaling is supported. Overhead bandwidth is notrequired through the multiplexer network for signaling.

The CELP Voice Channel Module mounts into the TMS-3000 or TMSCompact channel or expansion shelf. In the Univ. MM+ V4 TDM orMINIMUX TDM it mounts into the channel slot.

The CELP Voice Channel Module utilizes a 600 ohm 4-wire interface withE&M signaling and connects to the voice terminating equipment via aGDC standard voice channel connection cable.

The CELP Voice Channel Module (-002) supports Group 3 FAX transfers atthe 6.4 kHz voice multiplexer data rate with in-band E&M signalling.

The CELP Voice Channel Module (-003) supports 4.8 kHz voice only within-band E&M signalling.

The CELP Voice Channel Module (-004) supports voice and Group 3 FAXtransfers at the 6.4 KHz voice multiplexer data rate with In-band E&Msignaling. When operating in a TMS-3000, 9.6 kHz is also available.

The CELP Voice Channel Module (-005) supports 4.8 kHz voice only within-band E&M signalling. When operating in a TMS-3000, 9.6 kHz is alsoavailable.

1-1

INTRODUCTION

FUNCTION OFTHE TMS/

SUPERVISORYCONTROLLER

NOTE

In the TMS-3000 and TMS Compact, the Controller isreferred to as the TMS-3000 Controller, TMS Controller orController. In the Univ. MM+ V4 TDM and MINIMUXTDM, the Controller is referred to as the Supervisory Con-troller.

In this manual, the abbreviation TMS/Supervisory Controller will beused.

The TMS/Supervisory Controller performs the following functions:

• Recognize the type of voice card

• Configure the voice card

• Program the voice card hardware according to line speed, etc.

• Monitor and report status and alarms, and

• Support diagnostic procedures involving the voice card.

TECHNICALMANUALS

To assist in installation of the CELP Voice Channel Module, it is rec-ommended that the following manuals be available:

If installing in a TMS-3000:

• Operating and Installation Instructions Manual for TMS-3000, GDCPublication No. 036R303-000 and TMS-3000 User's Guide for SoftwareVersion GTS 2.0 (or later), GDC Publication No. 036R603.

Installing in a TMS Compact:

• Instruction Manual for TMS Compact, GDC Publication No. 036R320-000 and TMS-3000 User's Guide for Software Version GTS 2.0 (orlater), GDC Publication No. 036R603.

Installing in a Univ. MM+ V4 TDM:

• Instruction Manual for the MEGAMUX PLUS TDM, GDC PublicationNo. 036R360-000 and the Operator's Instructions for the MEGAMUXPLUS TDM, GDC Publication No. 036R660-000.

Installing in a MINIMUX TDM:

• Instruction Manual for the MINIMUX TDM, GDC Publication No.036R333-000.

1-2

INTRODUCTION

EQUIPMENT LIST The components that make up the CELP Voice Channel Module are pre-sented in Table 1-1. Available features are shown in Table 2-2. The partnumbers in the list generally represent assemblies made of severaldiscrete parts. Technical Characteristics of the CELP Voice ChannelModule are given in Appendix A.

SERVICE ANDTRAINING

See Section 5, TESTS, for information on service and training availablefrom GDC.

APPLICATIONS Appendix B contains typical applications of the CELP Voice ChannelModule.

TABLE 1-1. EQUIPMENT LIST

Equipment Supplied Designation GDC Part No.CELP Voice Channel Module

CELP Plug-in — 036P285-001, -002, -003, -005CELP Basecard — 036P286-001

TABLE 1-2. FEATURE LIST

Voice Module Equipment Features036M285-001 (CELP 1) 036P285-001

036P286-001Voice at 6.4/4.8 kHzE&M signalling – out of band

036M285-002 (CELP/FAX) 036P285-002036P286-001

Voice at 6.4/4.8 kHzE&M signalling – in-band/out-of-bandFAX Group 3 at 6400 bps rate

036M285-003 (CELP 2) 036P285-003036P286-001

Voice at 4.8 kHzE&M signalling in-band/out-of-band

036M285-004 CELP 96/FAX 036P285-005036P286-001

Voice at 9.6/6.4/4.8 KHz E&Msignaling in-band and out-of-band FAXGroup 3 at 9.6/6.4 KHz rates

036M285-005 CELP 96 036P285-005036P286-001

Voice at 9.6/4.8 KHz E&M signaling in-band and out-of-band

NOTE

9.6 kHz is available only in TMS-3000.

1-3

SECTION 2

INSTALLATION

UNPACKING ANDHANDLING

Inspect the CELP Voice Channel Module for damage; if any is found, no-tify the shipper immediately. Do not discard the box and packing mate-rial; their use will facilitate reshipping the unit, if necessary.

INSTALLATIONPROCEDURES

In the TMS-3000 or TMS Compact, the CELP Voice Channel Modulemounts into the channel or expansion shelf. In the Univ. MM+ V4 orMINIMUX TDM, the CELP Voice Channel Module mounts into a channelslot. The shelf should be located in a ventilated area where the ambienttemperature does not exceed 124°F (50°C). Do not install the unit directlyabove equipment that generates a large amount of heat (such as powersupplies). Table 2-2 lists the various cables required for specific CELPapplications.

PREOPERATIONALCHECK

In many instances, a CELP Voice Channel Module may seem to be inop-erative in a particular system, when actually the pc board jumper posi-tions or software options have been improperly selected or a fault existselsewhere in the system.

The CELP Voice Channel Module supports several diagnostic tests thatcan be performed through the TMS/Supervisory controller. Section 5 de-scribes these tests.

If the CELP Voice Channel Module passes these tests, but subsequentlyfails to perform voice communications, the CELP may not be at fault. Anerror may have been made in the installation or configuration, or thereis a faulty communication line or faulty remote installation. Recheck thecables, line connections, the option strapping, and soft option selection.

In the event that the CELP Voice Channel Module does not check outproperly, replace it with a spare CELP Module, if available. Do notattempt to repair the CELP Module. For assistance, contact DataCommService Corporation (see Section 5).

OPTIONSELECTION

The CELP Module contains both hardware and software optioning. Thismanual deals mainly with the hardware configuration of the CELPModule. To configure software options on a CELP Voice Channel Moduleinstalled in the TMS-3000 or TMS Compact, refer to the TMS-3000 User'sGuide for Software Version GTS 2.0 (or later), GDC Publication No.036R603.

To configure software options on the Univ. MM+ V4 TDM, refer to theOperator's Instructions for the Univ. MM+ V4 TDM, GDC Publication No.036R660-000.

To configure software options on the MINIMUX TDM, refer to the Instruc-tion Manual for the MINIMUX TDM, GDC Publication No. 036R333-000.

2-1

INSTALLATION

There is one hardware option on the piggyback card. That option isdescribed in Table 2-1.

TABLE 2-1. CELP PLUG-IN OPTION, SIGNALING TYPE

Feature Jumper X1 ApplicationE&M Signaling E&M Normal jumper positionAC15 Signaling AC15 Future use jumper position

Note that switch SW1 on the piggyback card has been adjusted at thefactory. Do not under any circumstances change the settings of SW1 onthe piggyback card.

Figure 2-1 shows the location of the option switches and jumpers on theCELP base card.

Tables 2-3 through 2-10 provide the information necessary to configure theCELP Voice Channel Module for the TMS-3000.

2-2

INSTALLATION

UK

S1

ON 1 2 3 4 5 6 7 8

S2

FL1

FL2

FL3

TP3TP2TP1

UK

US

UK

DS3

DS4

X3 X2

X1 X4 X5 X6 X7 X8

X9INT

GND

GND

BAT

GND

BAT

M

M

US IDL

BSY

+

-

+PIGGYBACK P/N 036P285

CELP PIGGYBACK CARD

036P286-001

NOTE

JUMPERS SHOWN IN DEFAULT POSITION.

DS1

DS2

J1

INT

M

IDL

BSY -

US

DEFAULT FOR S1-1 THROUGH S1-8 IS OFF. THIS PROVIDES O dBm TRANSMIT AND O dBm RECEIVE LEVELS. DEFAULT FOR S2-1 THROUGH S2-4 IS OFF. DEFAULT FOR S2-5 IS ON S2-6 THROUGH S2-8 IS OFF.

TYPE I SIGNALING REQUIRED TO INTERFACE TO TELLABS SATE MODULES. JUMPER X5 AND X6 SHOULD BE SET TO IDL FOR PLAR CIRCUITS.

XA

1J1

XA

1J2

NOTE

X11CSIG

NORM

FIGURE 2-1. CELP OPTION LOCATIONS

2-3

INSTALLATION

MOUNTING OFCELP VOICE

CHANNELMODULE

The CELP Voice Channel Module consists of two subassemblies, theCELP base card and piggyback card. The CELP base card is a standardGDC channel card 9 in. x 6.25 in. (22.86 cm x 15.88 cm) with edge fingerconnections to the harness card on the opposite side to the front panel.

The CELP Voice Channel Module piggyback card is 6 in. x 4.6 in. (15.24cm x 11.43 cm). It mounts onto the base card with the component side fac-ing down via two sockets. Standoffs provide 0.5-inch (1.27-cm) spacing be-tween the cards.

The CELP Voice Channel Module mounts into an empty channel slot inthe TMS-3000, TMS Compact, Univ. MM+ V4 or MINIMUX TDM.Connections to the 4-wire VF line are made via standard GDC voicechannel cables (refer to Table 2-2).

TABLE 2-2. VOICE CHANNEL CONNECTION CABLESGDC Cable No. Description Application027H306 Voice Channel, DB-25 connector to spade

lugsSingle channel connection; tip, ring, E-lead, M-lead, andground brought out to spade lugs. Available in 5-, 15-, and25-foot lengths.

027H409 Voice Channel, DB-25 connector to punch-down wire leads

Single channel connection; tip, ring, E-Lead, M-Lead, sta-tion battery, signal and station ground brought out to wireends for punch-down applications. Available in 5-, 15-,and 25- foot lengths.

326H024 TMS-3000, TMS Compact, MM PLUS orMINIMUX TDM to PBX;DB-25 connector to 50-pin Amphenolconnector. Up to 8 voice channels.

Used to connect up to 8 voice channels to private branchexchange. 5-foot length only; requires 021H605-025 ex-tension cable.

326H025 8-channel harness; DB-25 connector to50-pin Amphenol connector

Used to connect up to 8 voice channels to facility.Transmit and receive leads crossed over. 5-foot only.Requires 021H605-025 extension cable.

326H026 6-channel harness; DB-25 connector to50-pin Amphenol connector

Used to connect up to 6 voice channels to facility.

021H623 TMS-3000, TMS Compact, MM PLUS orMINIMUX TDM to Tellabs 266D shelf (6voice channels)

Used to connect up to 6 voice channels to Tellabs 266ARshelf. Available in 5- or 15-foot lengths.

021H622 TMS-3000, TMS Compact, MM PLUS orMINIMUX TDM to Tellabs 266XR-12 shelf(12 voice channels)

Used to connect up to 12 channels to Tellabs 266ARshelf. Available in 5- or 15-foot lengths.

830-002S008 50-pin Amphenol male to male extensioncable (25 pairs)

Used to connect 50-pin cables above to customer voicetermination point (demark), (voice channel to PBX).

830-002S007 50-pin Amphenol male to femaleextension cable (25 pairs)

Used to connect Tellabs shelf to customer voice termina-tion point (demark) (Tellabs Shelf to PBX).

2-4

INSTALLATION

CELP VOICECHANNEL

SIGNALING

The CELP Voice Channel Module supports 4-wire voice with two-stateE&M signaling only. The five major E&M signaling systems (E&Mtypes I-V) are supported. For the United Kingdom, SSDC5A is supported.

As previously mentioned, the CELP Voice Channel Module provides two-state signaling only. An "M" Lead input produces an "E-lead" output atthe remote multiplexer channel. The M-signal input into the base cardwill vary according to the signaling type selected. The base card is op-tioned for the appropriate signaling type using jumpers as shown inTable 2-3.

Type I signaling is generally used to interface to Signaling And Termi-nating Equipment (SATE).

The E-lead output from the CELP Voice Channel Module is a solid-stateFET (field effect transistor) switch with a low resistance signifying abusy condition. In order to read the busy state of the E-lead to stationground, the external equipment (SATE, PBX channel, etc.) must be con-nected as the voice channel switching circuitry is powered by the externalequipment (via the E-lead).

M-Lead Signaling interface diagrams can be found in Appendix C.

TABLE 2-3. OPTION SELECTIONS, M-SIGNALING TYPES

Signaling Jumper Positions M-Signaling StatesType X1 X2 X3 X4, X9 Idle Busy Application

I GND M GND U.S. 0 Vdc –12 to –48 Vdc X1, X2, X3, X4 and X9 select

II GND M BAT U.S. OPEN –12 to –48 Vdc the proper interface for dif-

III GND M BAT U.S. 0 Vdc –12 to –48 Vdc ferent E&M signaling types.

IV M BAT GND U.S. OPEN 0 Vdc The jumper positions de-

V M BAT GND U.S. OPEN 0 Vdc pend on the E&M signaling

II * M INT INT U.S. OPEN 0 Vdc types used by the voice

SSDC5A M BAT GND U.K. OPEN 0 Vdc equipment connected to theCELP Module .

* For back-to-back signaling using no external battery.

Note 1: AT&T signaling types II through V require an external –48 volt supply to be connected to the Negative Battery (NBATT) input pin.

Note 2: Signaling types I, IV, V and SSDC5A require a local ground to be used for the return lines of either the E or M leads. This could be achievedby adding a jumper in X3 (INT position); alternatively, a more reliable way is to externally connect the local Station Ground to the SG pin on themultiplexer. All other signaling types require the local station ground to be connected externally to the SG pin on the multiplexer.

Note 3: Type II signaling (back-to-back) requires signaling connections between the back-to-back CELP Modules (as shown in the table below):

LOCALCELPVOICECHANNELMODULE

REMOTECELPVOICECHANNELMODULE

LOCALCELPVOICECHANNELMODULE

REMOTECELPVOICECHANNELMODULE

SB SG TIP IN TIP OUTSG SB RING IN RING OUT KEYE M TIP OUT TIP IN SB-STATION BATTERY

M E RING OUT RING IN SB-STATION GROUND

2-5

INSTALLATION

E-Lead SignalingState

Table 2-4 describes how the E-Lead signaling is conditioned on loss ofpower in the TMS-3000 controller.

TABLE 2-4. OPTION SELECTIONS, E-LEAD SIGNALING STATE

Jumper JumperX5 X6

Feature Position Position ApplicationLoss of PowerE-Lead Signaling State

Busy (BSY) Busy (BSY) With these two jumpers set in the position shown, theE-Lead (pin 24 on the DB-25 EIA connector) is in aBusy state during loss of power. This selection isgenerally made for connections between the voicechannel and PBX systems, or Tellabs and other voicetermination systems (Not in PLAR applications, seeNote below).

Idle ( IDL) Idle ( IDL) With these two jumpers set in the position shown, theE-Lead (pin 24 on the DB-25 EIA connector) is in anIdle state during loss of power. This selection is gen-erally made for connections between the voice chan-nel and automatic ringdown circuits.

Idle Busy Invalid. Do not use.

Busy Idle Invalid. Do not use.Note: Busy should not be used in private line automatic ringdown applications, as a loss of power will cause the phones at bothends to ring until power is restored.

E-Lead Polarity Table 2-5 describes the procedure for setting the E-Lead Polarity in rela-tion to Station Ground.

TABLE 2-5. OPTION SELECTIONS, E-LEAD POLARITY

Jumper JumperX7 X8

Feature Position Position ApplicationElectrical Polarity of E- – – E-Lead is negative.lead relative to Station + + E-lead is positive.Ground + – Invalid. Do not use.

– + Invalid. Do not use.

2-6

INSTALLATION

Noise SuppressionFilter

Table 2-6 describes the procedure for setting the Noise Suppression Filterfor the various E&M signaling types.

TABLE 2-6. OPTION SELECTIONS, NOISE SUPPRESSION FILTER

JumperX9

Feature Position ApplicationNoise Suppression Filter(NSF) as defined bySSDC5A specification

US, US NSF is disabled for signaling types I-V.

UK, UK NSF is enabled for SSDC5A signaling.

In-Band E&MSignaling

Table 2-7 describes the procedure for setting the Jumper X11 for in-bandE&M signaling types.

TABLE 2-7. OPTION SELECTIONS, IN-BAND E&M SIGNALING

JumperX11

Feature Position ApplicationIn-band E&M Signaling NORM E&M signaling is conveyed in-band via the voice

channel data. Any changes in the state of the input Mlead (high to low or low to high) will briefly interrupt thevoice traffic as the signaling information is conveyedend to end. For proper operation, pulse widths shallbe a minimum of 20 ms (20.625 ms at a 4.8 kHz datarate). This will yield a maximum of 0.625 pulse widthdistortion. Both ends of the circuit must be in NORMmode.

CSIG E&M signaling is conveyed via the "Controls"overhead in the multiplexer's aggregate data link.This is "out of band" since it is not conveyed via theCELP voice channel. We only recommend on-hook/off-hook type of E&M signaling with this methodsince no guarantee can be given regarding pulsewidth distortion. Both ends of the circuit must be inCSIG mode.

E&M Signaling Overhead CSIG To enable overhead E&M signaling. This positionshould be selected on all 036M285-001 assembliesand on 036M285-002 assemblies when a -001 is atthe other end of the CELP circuit.

NORM To enable true In-Band E&M signaling. This positionshould only be selected when both ends of the CELPcircuit are 036M285-002, -003, -004 or -005.

2-7

INSTALLATION

E-LeadLoss of Sync

The M-lead input at one end is normally conveyed to the E-lead output atthe other end with no more than one millisecond of timing distortion.When the CELP Voice Channel Module card loses end-to-endsynchronization, the E-lead is conditioned according to Table 2-8.

TABLE 2-8. OPTION SELECTION, E-LEAD CONDITION UPON LOSS OF SYNC

Dip SwitchSettings

Feature S1-6 S1-7 ApplicationForce E-lead to Idle ON ON Forces the E-lead to Idle when either the multiplexer or CELP Voice Channel

Module declare loss of end-to-end synchronization. This option terminates thecall in E&M applications or when used with Tellabs PLAR (Private Line AutomaticRingdown), preventing false rings.

Force E-lead to Busy OFF ON Forces the E-lead to Busy when either the multiplexer or CELP Voice ChannelModule declares loss of end-to-end synchronization. This option will cause thecircuit to be busy, preventing further calls.

Freeze E-lead ON OFF Freezes the E-lead when either the multiplexer or the CELP Voice ChannelModule declares loss of end-to-end synchronization until synchronization isrestored again. This option attempts to hold the call on a PBX. This option is notrecommended for the CELP module since the state of the E-lead is not reliable atthe instant of freezing.

Disconnect the Call OFF OFF This option is recommended when operating on the analog tie-lines (trunk lines)of PBXs. This option causes the call to be terminated and the line "busied" out toprevent furthur access upon loss of end-to-end synchronization. The E-leadgoes Idle for 3 seconds to terminate the call. Then the E-lead goes busy for aminimum of 3 seconds and stays busy until the restoral of end-to-endsynchronization.

2-8

INSTALLATION

CELP ModuleAnalog Levels

The nominal VF input and output analog levels are selected by DIPswitches S1-1 and S1-8. Table 2-9 describes the setting of these switches.These switches are programmed for peak levels with a safety margin ofapproximately 3 dB allowed.

TABLE 2-9. OPTION SELECTION, INPUT/OUTPUT LEVELS

Switch(S), Jumper(X)Feature Selection Desig. Position Application

Nominal Input Level 0 dBm

– 16 dBm

S1-1

S1-1

OFF

ON

The nominal input level selection is deter-mined by the nominal output level of thetelephone equipment connected to thechannel. Most systems specify either 0 dBmor –16 dBm as their nominal output. If actualoutput levels of connected equipment varyfrom the nominal levels of 0 dBm or –16 dBm,switches S1-2, S1-3, S1-4 and S1-5 may beset to achieve some level of compensation inthe range of –6 dB to +1.5 dB.

Nominal Output Level +7 dBm

0 dBm

S1-8

S1-8

ON

OFF

The nominal output level for the Voice Chan-nel is either 0 dBm or +7 dBm. This selectiondepends on the nominal input expected intothe telephone equipment connected to thechannel. Adjustments to the actual measuredoutput level of the voice channel may bemade through the CRT interface, by setting adegree of attenuation or amplification in therange of – 6 dB to + 1.5 dB.

NOTES0 dBm input and output levels are pre-ferred, where possible.

The transmit nominal input level of–16dBm actually amplifies the input by16 dBm. A setting of 0 dBm performsno amplification.

2-9

INSTALLATION

Analog InputFine Level

Adjustments

The analog sections in both transmit and receive directions have ad-justments to fine tune the signal amplitude to compensate for installa-tions where the input levels are not within the –16 to + 0 dB range or whenexcessive output cable lengths require greater than nominal signal drive.

The amplitude of the input transmit signal to the transmit circuit can beadjusted in 0.5 dB steps in the range –6.0 to +1.5 dB (approximately a 0 to–16 dBm transmit level selection) by DIP switches S1-2, S1-3, S1-4 and S1-5. Refer to Table 2-10 for setting of the DIP switches.

Similarly, the amplitude of the output receive signal from the receive cir-cuit can be adjusted in 0.5 dB steps in the range –6.0 to +1.5 dB(approximately a 0 to + 7 dBm receive level selection) by software via theTMS/supervisory controller.

For instructions on how to align the levels, refer to Appendix D, CELPCircuit Voice Level Testing.

TABLE 2-10. OPTION SELECTIONS, INPUT LEVEL ADJUSTMENT

S1-2 S1-3 S1-4 S1-5 Input(–2 dB) (+1 dB) (–4 dB) (+0.5 dB) Compensation Application

OFFOFFOFFOFFONONONONOFFOFFOFFOFFONONONON

ONONOFFOFFONONOFFOFFONONOFFOFFONONOFFOFF

OFFOFFOFFOFFOFFOFFOFFOFFONONONONONONONON

ONOFFONOFFONOFFONOFFONOFFONOFFONOFFONOFF

+1.5 dB+1.0 dB+0.5 dB0.0 dB

–0.5 dB–1.0 dB–1.5 dB–2.0 dB–2.5 dB–3.0 dB–3.5 dB–4.0 dB–4.5 dB–5.0 dB–5.5 dB–6.0 dB

Switches S1-2 through S1-5 select attenuationor amplification for the voice input level. Thiscompensates for cable losses or improperoutput levels from connected telephoneequipment. The switch selects a level ofcompensation from +1.5 dB to –6.0 dB, in 0.5dB steps. Each segment of switch S2 selects alevel of attenuation or amplification; theindividual steps are added to produce aparticular level. A level is selected tocompensate for some measured deviation ofthe output level of equipment connected to thechannel. The deviation is the differencebetween the actual level and the nominal levelof 0 dBm or –16 dBm selected on switch S1-1.For example, if the nominal level is 0 dBm, andthe actual level is +2 dBm, selection of –2 dBwould compensate for the difference betweenthe nominal and measured input values.

2-10

INSTALLATION

Echo Canceller The CELP Module contains an Echo Canceller. This Echo Canceller canneutralize echo in tail circuits up to 8ms round trip delay. When the tailcircuit delay is greater than this value then an external echo cancellermust be used. Note that any echo cancellation circuitry in the tail circuit(in the range of 0 to 8ms) e.g. in a PBX must be disabled. The CELP EchoCanceller can not be disabled (See Table 2-11).

TABLE 2-11. OPTION SELECTIONS, CODEC TIMING

Switch (S)Feature Selection Desig. Position Application

CODEC TimingSource

Basecard S2-5 OFF This switch controls the source of timing for thebasecards CODEC IC. The CELP Plug-in alwaysneeds to supply timing for the CODEC.

Plug-in S2-5 ON Therefore, this switch should always be in the “ON”position when the CELP plug-in is present.

Not Used S2-1S2-2S2-3S2-4S2-6S2-7S2-8

OFFOFFOFFOFFOFFOFFOFF

Echo Canceller is always enabled

2-11

SECTION 3

INSTALLATION

OVERVIEW The CELP Voice Channel Module operates automatically after it is in-stalled (refer to Section 2, Installation). You simply send and receiveanalog voice signals while the CELP Voice Channel Module functionstransparently. You may check the operation of the CELP Voice ChannelModule by monitoring the front panel indicators.

CONTROLS,INDICATORS AND

CONNECTORS

Figure 3-1 illustrates the CELP Voice channel module front panel and ex-plains the function of each control and indicator. Connector pin assign-ments for the CELP Voice channel module are described in Appendix E ofthis manual.

3-1

OPERATION

A RED LED INDICATOR LIGHTS WHEN AN ALARM CONDITION EXISTS IN THE CHANNEL. SOMEPOSSIBLE ALARM CONDITIONS ARE: TRANSMITCLOCK BAD, RECEIVE CLOCK BAD, CHANNEL OUT OF SYNC AND DIAGNOSTIC TESTS IN PROGRESS. THE LED ALSO LIGHTS IF THE CARD IS INSTALLED IN AN UNDEFINED SLOT.

I n S v c e

CELPVOICECHAN

E

M

C h a nA l m

L E V E L

AMBER LED LIGHTS WHEN THE E-LEADOF THE VOICE CHANNEL IS IN A BUSYSTATE. OUTPUT FROM THE VOICE CHANNEL IS IN THE FORM OF A SOLID STATE SWITCH. LOW RESISTANCE EQUALS A BUSY CONDITION (E-LEAD TO GROUND). E-SIGNAL IS A PRODUCT OF THE REMOTE CHANNELS M-SIGNAL.

A GREEN LED INDICATOR LIGHTS WHEN THECHANNEL IN THE CURRENTLY ACTIVE TDM CONFIGURATION,INDICATING THAT THE CARD IS EITHER OPERATING OR PREPARED TO OPERATE ACCORDING TO THE PARAMETERS ENTERED FOR THAT CHANNEL IN THE ACTIVE CONFIGURATION. WHEN OFF, THE CHANNEL IS OUT OF SERVICE. WHEN OUT OF SERVICE, THE CONTROL LEADS ARE CONDITIONED.

TEST POINT FOR BRIDGED MEASUREMENT OFVOICE CHANNEL VF INPUT LEVEL TO THE TRANSMIT SECTION. TEST POINT ISOLATED THROUGH 10-KILOHM RESISTOR. INPUT LEVELS SHOULD BE 0 dBm OR –16.0 dBm. THIS TEST POINT IS A HIGH IMPEDANCE INPUT AND IS NOT FOR INJECTION OF TONES.

V F I n

V F O u t

G n d

S I G N A LAMBER LED LIGHTS WHEN THE M-LEADOF THE VOICE CHANNEL IS IN A BUSYSTATE.

TEST POINT FOR BRIDGED MEASUREMENT OFVOICE CHANNEL VF OUTPUT LEVEL FROM THE RECEIVE SECTION. TEST POINT ISOLATED THROUGH 10-KILOHM RESISTOR. OUTPUT LEVELS SHOULD BE 0 dBm OR +7.0 dBm

ANALOG GROUND POINT FOR VF INPUT AND VF OUTPUT MEASUREMENT.

NOTE

The E&M and Alarm indicators are still functionalwhen the card is not in service.

FIGURE 3-1. CELP VOICE CHANNEL MODULE, FRONT PANEL

3-2

SECTION 4

PRINCIPLES OF OPERATION

OVERVIEW This section describes the general circuit functions of the CELP VoiceChannel Module. Signal flow and processing through the CELP Module isdescribed to show the relationship of the hardware and interconnectionwith external equipment.

Base CardOperation

Analog voice information is directed into the transmit section of theCELP base card via a standard 600-ohm transformer coupled telephoneinterface. This signal is sent to an analog level conditioning circuit.

The standard input transmit levels are –16.0 and 0 dBm. These levels areselectable through a DIP switch and can be adjusted through hardware in0.5-dB steps in the range of –6.0 dB to +1.5 dB.

This conditioned analog signal then goes through an analog-to-digitalconversion process and is sent to the CELP piggyback card for bit rate re-duction.

The reduced bit rate signal is received from the piggyback at 9.6, 6.4 or4.8 kHz and then passed via an elastic buffer to the multiplexer transmitdata bus. The elastic buffer absorbs any jitter acquired in the data streambefore its passage into the multiplexer.

Receive voice data is sent from the multiplexer at the reduced bit rate andpassed through a receive elastic buffer (similar to the transmit buffer) onits way to the CELP piggyback card.

The receive data comes from the piggyback as regular PCM data at 64kHz. It is sent to the base card and converted to an analog signal. Thisanalog signal passes through a level conditioning circuit (the output pad),where its level is adjusted before being output to the user via a standardtransformer coupled 600-ohm line. The output pad for the receive analogsignal consists of three sections.

The standard receive output levels are 0 and +7.0 dBm. These levels areselectable through a DIP switch and is adjusted through software in 0.5-dBsteps in the range –6.0 dB to +1.5 dB.

E&M Signaling(-001 Version)

The -001 version of the CELP Voice Channel Module uses overhead con-trol bandwidth to pass E&M signaling through the network. The amountof control bandwidth required depends upon various parameters.

This method works fine for simple ON-HOOK/OFF-HOOK applications(with either DTMF or no dialing). The amount of control bandwidth re-quired is not critical in these applications.

For pulse dialing applications, extra overhead bandwidth is required ifthe dial pulse distortion is required to meet certain standards (e.g.,

4-1


AT&T Pub 43801 or BT’s SSDC5A). The recommendation is for at least 4kHz of overhead bandwidth on Minimux/Univ. MM+ V4 aggregate links.Additional bandwidth is required if two or more CELP channels sharingan aggregate are likely to be dialing simultaneously.

Due to the complexity of calculating the overhead bandwidthrequirements of such systems, GDC does not recommend pulse dialingvia the CELP Voice Channel Module (-001) on TMS-3000/TMS Compactsystems .

E&M Signaling(-002, -003, -004,

-005 Versions)

The -002, -003, -004 and -005 versions of the CELP Voice Channel Moduleaccomplish E&M signaling using true in-band techniques. Thesignaling information is passed end-to-end via the voice channel withoutthe need for any extra bandwidth (there will be short breaks in the voicechannel when E&M signaling is being passed). The pulse distortion (625micro secs max) is considered to be acceptable for all applications. Theonly constraint is that signaling pulse widths must be greater than 20 ms(20.625 ms at 4.8 kHz). This is sufficient for all known regular pulsedialing systems (but 20 pps “speed dialing’’ systems will not besupported).

Note that for in-band E&M signaling, both ends of the voice link must bethe -002, -003, -004 or -005 CELP Modules. If one end of the CELP voice linkhas a -001 CELP Module then in-band signaling will not be supported.The “Overhead Control Bandwidth’’ method of E&M signaling must beused in this case.

Piggyback CardOperation

Serial PCM data at 64 kHz is sent from the base card and converted intoa low bit rate data stream for transmission to the multiplexer via the basecard. Simultaneously, low bit rate encoded voice is received from themultiplexer channel and converted back to serial PCM encoded voicedata at 64 kHz and returned to the base card.

The speech compression algorithm selection is based on the speed of thechannel rate clock (either 9.6 kHz, 6.4 kHz or 4.8 kHz).

Software informs the piggyback card which data rate is currently se-lected. The piggyback card detects a change in this bit rate and selects thenew algorithm.

Dialing and call progress tones are passed through the channel. TheCELP Voice Channel Module supports DTMF, MF, SF and 1-kHz testtones.

The CELP Voice Channel Module piggyback card also performs the func-tion of an echo canceller. The echo canceller calculates the amount ofecho in the input signal and attempts to cancel the echo with an equaland opposite computed echo signal. The echo canceller performance isequal to (or better) than CCITT G.165 specifications.

The -002, -003, -004 and -005 versions of the CELP Voice Module transfersE&M signaling information via the voice band. There is a short breakin the voice path every time the piggyback detects a change in thecondition of the M lead input.

4-2


If the M lead is in the Idle condition then the M lead information isretransmitted every 60 seconds. This causes a short break in the voicepath every 60 seconds.

Therefore it is important that on systems which do not use E&M signal-ing (e.g., open lines for traders) that the M lead is somehow forced intothe Busy state. It is not recommended that this is done using the diagnos-tic software since this would force on the Channel Alarm light on a per-manent basis and this could mask real channel alarms.

The -002 version of the card supports FAX bypass at the 6.4 kHz channeldata rate. The FAX data rate is normally 4.8 kHz, with a 2.4 kHzfallback rate if external line conditions dictate. FAX data is sent over thevoice channel. No voice traffic is possible during a FAX session.

The -004 version of the card supports FAX bypass at the 9.6 kHz or 6.4 kHzchannel data rate. The FAX data rate is normally 9.6 kHz with fallbackrates of 7.2, 4.8 and 2.4 kHz as defined by ITU-T.4.

NOTE

The 9.6 kHz channel data rate is available only in TMS-3000.

4-3

SECTION 5

TESTS

OVERVIEW This section describes the tests that may be performed on the CELP VoiceChannel Module after installation. These tests are performed using aTMS/Supervisory controller and are used to isolate problems in the datacommunications system. Tests are performed through the CELP VoiceChannel Module base and piggyback card only. A Technical Assistanceprocedure and CELP Voice Channel Module test point location is given atthe end of this section.

DATA PATH TESTSDigital Test

This test is performed in conjunction with a digital local or remote loop-back test. The test performs a rudimentary error rate check on the digitalportion of the channel module through the multiplexer network or in a lo-cal loop. An alternating "ones and zeroes" pattern is transmitted fromthe CELP Voice Channel Module and received from either the local orremote CELP Voice Channel Module. Errors are counted at the receivingend. This test causes a channel alarm to be raised and forces the E-leadto a Busy state to prevent access by a PBX.

Control State Test The Control State Test forces the M-Input at either end of the channel to a"busy" state. The E-lead at the remote end should be "Busy" as a result ofthe M-signal sent.

User Data Test The User Data Test creates a test path for use with external test equip-ment. When User Data Test is selected, the user voice data is looped ei-ther locally or at the remote end. Local loopback is performed at the digi-tal section of the local CELP Voice Channel Module card. Remote loop-back is performed at the analog section of the remote CELP Voice Chan-nel Module. Remote loopback includes almost all of the circuitry on bothCELP Voice Channel Modules.

1 kHz Tone Test This test sends a 1-kHz tone through the test path.

The channel module at the origin node generates a 1-kHz tone. This toneis then digitized and sent through the selected path.

In a circuit remote loopback test, the 1-kHz signal loops back at the ana-log section of the module. In a channel local test, the signal loops back inthe digital section of the module.

The 1-kHz tone may be monitored by connecting external test equipmentto the VF Out front panel test point of the originating channel.

5-1

TESTS

SET dB LEVELADJUSTMENT

The Set dB level adjusts the output level of the selected channel module tothe input requirements of the connected telephone equipment. The Rcv dBoutput level should be adjusted at both ends of the CELP Voice ChannelModule.

Note, the Rcv dB level is not considered a test but an adjustment. Thenominal Receive level (0 dBm or + 7.0 dBm) is set by switch S1-8 on theCELP Voice Channel Module. You may adjust that level through softwarewithin the range of +1.5 to –6.0 dB in 0.5 dB steps.

TEST POINTS The test points located at the bottom of the front panel provide access to in-put/output signals. The VF analog signals are isolated via a l0-kilohmresistor and are suitable for bridge measurement of VF levels. Section 3of this manual contains descriptions of each module's front panel indica-tor, including the test points. The following test points are found on theCELP Voice Channel Module's front panel:

TP3 VFIN Analog Input signal to the transmit section.TP2 VFOUT Analog Output signal from the receive section.TP1 GND Analog Ground

The voice signals in and out of the channel should be present at the VFINand VFOUT test points.

TECHNICALASSISTANCEPROCEDURE

For technical assistance, customers should call DataComm Service Cor-poration at 203-598-7526.

In Canada:

General DataComm (Canada) Ltd.Service and Repair Facility1790 Beaulac StreetSt. Laurent, Montreal, Quebec H4R 1W8Telephone: 1-514-336-5454TWX: 610-421-3221Telex: 05824085

In the United Kingdom, contact the GDC area manager at:

General DataComm (U.K.) Ltd.Molly Millars CloseMolly Millars LaneWokingham, BerkshireEngland RG11 2QFTelephone: 011-44-734-774-868Telex: 851 847298Fax: 011-44-734-774-871

In Europe/Africa/Middle East:

General DataComm3 Batiment SaturneParc Club ArianeRue Helene Boucher78284 Guyancourt Cedex, FranceTel: 011-33-1-30570200Fax: 011-33-1-30443794

5-2

TESTS

In the Pacific:

General DataComm Pty.Suite 404275 Alfred Street NorthNorth Sydney, NSW 2060, AustraliaTel: 011-61-2-956-5099Fax: 011-61-2-956-5083

In Asia:

General DataComm401 Centry Square1-13 D'Aguilar StreetCentral, Hong KongTel: 011-852-5265511Telex: 780-80579Fax: 011-852-5259944

In Latin America:

General DataComm, International1579 Straits TurnpikeP.O. Box 1299Middlebury, Connecticut 06762-1299Telephone: 203-574-1118Telex: 7400905Fax: 203-758-9518

To return a unit for repair, if so authorized by GDC, use the return tagand address the package:

Product Repair DepartmentGeneral DataComm, Inc.1579 Straits TurnpikeP.O. Box 1299Middlebury, Connecticut 06762-1299

Lease and Maintenance contract customers may call DataComm ServiceCorporation toll-free at 1-800-243-1030, 24 hours a day, 7 days a week fortrouble reporting or installation scheduling. (Installations are normallyscheduled between 8 a.m. and 5 p.m.)

TRAINING Hands-on training courses are available from DataComm Service Corpo-ration Educational Services in the USA and in the UK. Courses offeredrange from basic data communications, modems and multiplexers, tocomplex network systems, and are given at GDC’s Connecticut facility orat a customer’s location.

For information call:

USA (203) 574-1118, Ext. 6190UK (44-734) 774-868

5-3

APPENDIX A

TECHNICAL CHARACTERISTICS

Item SpecificationsElectrical

Power Requirements: CELP assembly + 5 V dc ±5%, .70 A, typical, 1.0 A maximum, 3.50 W, typical+ 12 V dc ±10%, 7 mA, typical, 10 mA, maximum, 0.084 W, typical– 12 V dc ±10%, 30 mA, typical, 40 mA, maximum, 0.36 W, typical

Telephone Interface (4-wire/E&M)Impedance 600-ohms resistiveReturn Loss 18 dB minimum, (300-3400 Hz)Longitudinal Balance 56 dB minimum, (300-3400 Hz)Usable Audio Bandwidth 300-3400 HzIdle Channel Noise Less than –65 dBm0p at 6.4 and 4.8 kHz.

Transmission LevelsTransmit Section:

Nominal Input Level –16 dBm or 0 dBm (switch selectable)Input Adjustments (around nominalin put level)

–6 dB to +1.5 dB in 0.5-dB steps. Adjustments made by DIP switch.

Receive SectionNominal Output Level 0 dBm or +7 dBm (switch selectable)Output Adjustments – 6 dB to +1.5 dB in 0.5-dB steps. Adjustments made in software.

Data RatesMultiplexer 9.6, 6.4 or 4.8 kHz

M-Lead Input CharacteristicsU.S. E&M (Types I-V)M-Lead Input Resistance 2.4 kilohms (approximately)Threshold Currents

Idle 1 mA or less (M-lead to station ground)Busy 2.0 mA or greater (M-lead to station ground)

U.K. SSDC5A An earth via resistance of up to 1500 ohms in parallel with a capacitor of 1 micro-farad ±10% applied to the M-lead draws a minimum of 5 mA and is recognized as aBusy condition.An earth via resistance of greater than 400-kilohms in parallel with a capacitor of1 microfarad ±10% applied to the M-Lead is recognized as an Idle condition.

E-Lead Output CharacteristicsIdle leakage Current 500 microamps maximum at 64 VMax “on” voltage 2.0 V at 5 mA

2.5 V at 50 mA

A-1

APPENDIX A

TECHNICAL CHARACTERISTICS (Cont.)

Item SpecificationsEcho Canceller

Maximum Tail Circuit Delay 8 ms

In-Band E&M Signaling (-002 and -003)

Bandwidth Overhead No overhead bandwidth required.

Pulse Distortion ±625 microseconds.

Minimum pulse width 20 ms for a 6.4 kHz channel20.625 ms for a 4.8 kHz channel.

FAX Bypass (-002 only)

Protocol CCITT Group 3-T.4 (1988), T.30 (1988).

Transfer Rate Protocol V.21 (300 bps)Data V.29 (9.6/7.2 kHz) or V.27 ter (4.8/2.4 kHz)

Channel Rate 6.4 kHz.

Physical

Base card 9.0 in. x 6.25 in. (22.86 cm. x 15.88 cm.)

Piggyback Card 6.0 in. x 4.6 in. (1.5.24 cm. x 11.68 cm.)

Environmental

Operating Temperature* 32°F to 124°F (0°C to 50°C)

Nonoperating –40°F to 186°F (–40°C to +85°C)

Humidity 95% relative humidity with no condensation

Altitude

Operating 10,000 ft (3048 m)

Nonoperating 40,000 ft (12,192 m)* Derate operating temperature by 1°C/1000 ft. above sea level

A-2

APPENDIX B

CELP VOICE CHANNEL MODULE APPLICATIONS

OVERVIEW The CELP Voice Channel Module reduces the effective data bandwidthrequired by a speech circuit passing through the TMS-3000/TMS Compact,Univ. MM+ V4 or MINIMUX TDM network. Three bit rates are offeredunder software control: 4.8, 6.4 or 9.6 kHz. The speech compressionfunction will be performed using digital signal processing techniques. Ittakes a standard E&M speech channel and, through speech reductionalgorithms, defines parameters of the speech. These parameters are thentransmitted at a lower bit rate to the receiving end where they arereconstituted back into speech again.

Quality TelephoneVoice

The CELP Voice Channel Module provides good business communica-tions quality voice channels at 4.8, 6.4 kHz or 9.6 KHz. Customerstypically find the voice quality at these rates to be more than acceptablefor their purposes. An all-digital "echo canceller" conforming to CCITTrecommendation G.165 has been included on the CELP Voice ChannelModule. This eliminates the need for cumbersome external echocancellation equipment in most applications.

FAX Bypass Option This voice channel is designed for conveying speech. Other audio forms(e.g., music), may not be transmitted. Modems will not transmit datasince phase information contained in the carrier will be lost.

One main application of the CELP Voice Channel Module is to maximizevoice channel capacity of n x 64 kHz aggregates on TMS-3000/TMSCompact, Univ. MM+ V4 and MINIMUX TDM networks. This isespecially important on long haul routes where bandwidth costs remainhigh.

As shown in Figures B-1 and B-2, two PBXs communicate via their ana-log tie lines through a user's private TMS-3000/TMS Compact, Univ.MM+ V4 or MINIMUX TDM network, respectively. Analog voice iscompressed into digital data in the CELP Voice Channel Module andtransmitted via data links to a remote CELP Voice Channel Module. Thisreduces many of the noise and quality signal problems associated withanalog tail circuits in public telephone networks. Existing voice linescan thus be eliminated or a new voice network added with no increase inline cost. In the U.S. or Canada, simply connect the CELP Voice ChannelModule between a TMS-3000/TMS Compact, Univ. MM+ V4 or MINIMUXTDM and a spare port of your telephone system and you have a privatevoice circuit. There is no costly upgrading of existing equipment, noincrease in line costs and minimum installation/maintenance costs.

B-1

APPENDIX B

Larger networks with 56 kHz and 64 kHz circuits can also utilize theCELP Voice Channel Module to maximize usage of bandwidth. Voicechannels at higher rates quickly absorb much of the data capacity, andrestrict the potential number of voice circuits. The CELP Voice ChannelModule may provide additional voice channels at 4.8, 6.4 or 9.6 kHzwithout impacting the total bandwidth available for data. This capabilitymakes the CELP Voice Channel Module particularly well suited toapplications in the financial community, such as communicationsbetween dealer rooms in global trading networks (see Figures B-3 and B-4).

The CELP Voice Module supports in-band E&M signaling. The pulse dis-tortion level of 0.625 ms and the 20 ms minimum pulse requirement arecompatible with 10 pulse per second dialing systems the world over.

If the CELP Voice Module is used in an application which does not re-quire E&M signaling, such as in open lines between brokers, then in or-der to ensure that breaks do not occur in the voice path every minute dueto the requirement to retransmit the M lead information, the M lead mustbe tied in the BUSY state.

There are various means available for forcing the M lead BUSY. Oneway which may be considered is to configure the M Lead jumpers on thebase card as follows:

X1 — One jumper in the GND position.X2 — One jumper in the INT position.X3 — One jumper in the INT position and one jumper in the

GND position.X4 — One jumper in the US position.

The FAX bypass feature connects FAX machines which comply withCCITT Group 3 standards. This feature requires that the CELP Voice cir-cuit is operating at 6.4 kHz. The actual FAX transfers will take place at4.8 kHz. If the tail circuits are long then the FAX transfers may down-speed, under control of the FAX machines, to the fallback rate of 2.4 kHz.

B-2

APPENDIX B

PBX

PBX

PBX

ANALOGTRUNKS

ANALOGTRUNKS

SATELLITELINK

N X 64 KBPS

OR T1/E1

UNIV. MM+ V4

TMS-3000 ORTMS COMPACT

MINIMUX TDM

FIGURE B-1. CELP VOICE CHANNEL MODULE USED IN PBX ANALOG TIE TRUNK (TMS-3000, TMS COMPACT AND

UNIV. MM+ V4 APPLICATION)

PBX

PBX

PBX

ANALOGTRUNKS

ANALOGTRUNKS

SATELLITELINK

MINIMUX TDM

MINIMUX56/64 KBPS

PBX

MINIMUX MINIMUX

N X 64KBPS N X 64

KBPS

FIGURE B-2. CELP VOICE CHANNEL MODULE USED IN PBX ANALOG TIE TRUNK (MINIMUX TDM APPLICATION)

B-3

APPENDIX B

DEALERROOM

DEALERROOM

DEALERROOM

LONDONNEW YORK

56K

56K

TOKYO

TMS-3000

64K

TMS-3000

TMS-3000

FIGURE B-3. DEALER ROOM-TO-DEALER ROOM COMMUNICATIONS(TMS-3000/TMS COMPACT APPLICATION)

DEALERROOM

DEALERROOM

DEALERROOM

LONDONNEW YORK

56K

64K

TOKYO

TMS-3000 MINIMUX

MINIMUX

FIGURE B-4. DEALER ROOM-TO-DEALER ROOM COMMUNICATIONS(MINIMUX TDM APPLICATION)

B-4

APPENDIX C

M-LEAD SIGNALING INTERFACES

OVERVIEW Figures C-1 through C-7 represent M-lead signaling interface diagramsfor GDC voice channel card types to external equipment.

TYPE-I SIGNALING

X1 ON CELP MODULEX1 ON VOICE II/ASP CHANNEL MODULE AND UNIVERSALVOICE CARDX1 ON VLBRV CHANNEL MODULEX4 ON UNIVERSAL VOICE II/CVSD CHANNEL MODULEX4 ON VOICE II/PCM & ADPCM CHANNEL MODULES

A

M-LEAD SENSOR(ISOLATED)

M-LEAD OUT

GND M

-12 V

- BATT

SB

N.C.

N.C.

-12 TO -48 V

TERMINATING EQUIPMENT

VOICE CHANNEL

SG

M

PTC

BATT

BATT M

GNDD

INT

INT

A

X2 ON CELP MODULEX2 ON VOICE II/ASP CHANNEL MODULE AND UNIVERSAL VOICE CARDX2 ON VLBRV CHANNEL MODULEX5 ON VOICE II/CVSD CHANNEL MODULEX3 ON VOICE II/PCM & ADPCM CHANNEL MODULES

B

X3 ON CELP MODULEX3 ON VOICE II/ASP CHANNEL MODULE AND UNIVERSAL VOICE CARDX3 ON VLBRV CHANNEL MODULEX6 ON VOICE II/CVSD CHANNEL MODULEX5 ON VOICE II/PCM & ADPCM CHANNEL MODULES

C

B

C

NOTE: X2, X6 AND X10 ON EAM-1 PIGGYBACK BOARD IN U.S. POSITION.

X4 AND X9 ON UNIVERSAL VOICE CARD IN U.S. POSITION.

+

—

IDLE

BUSY

8

3

2

15

FIGURE C-1. M-LEAD SIGNALING INTERFACE,TYPE-I SIGNALING

C-1

APPENDIX C


M-LEAD OUT

GND M

-12 V

- BATT

SB

-12 TO -48 V


VOICE CHANNEL

SG

M

PTC

BATT

BATT M

D

INT

INT

A

B

C

B

CX1 ON VOICE II/ASP CHANNEL MODULE AND UNIVERSALVOICE CARDX1 ON VLBRV & CELP CHANNEL MODULEX4 ON UNIVERSAL VOICE II/CVSD CHANNEL MODULEX4 ON VOICE II/PCM & ADPCM CHANNEL MODULES

X2 ON VOICE II/ASP CHANNEL MODULE AND UNIVERSAL VOICE CARDX2 ON VLBRV & CELP CHANNEL MODULEX5 ON VOICE II/CVSD CHANNEL MODULEX3 ON VOICE II/PCM & ADPCM CHANNEL MODULES




P1

—

A

+

BUSY

IDLE

TYPE-II SIGNALING

FIGURE C-2. M-LEAD SIGNALING INTERFACE,TYPE-II SIGNALING

C-2

APPENDIX C


M-LEAD OUT

GND M

-12 V

- BATT

SB

-12 TO -48 V


VOICE CHANNEL

SG

M

PTC

BATT

BATT M

D

INT

INT

A

B

C

B






P1

—

A

+

975 Ω

IDLE

BUSY

TYPE-III SIGNALING

FIGURE C-3. M-LEAD SIGNALING INTERFACE,TYPE-III SIGNALING

C-3

APPENDIX C


M-LEAD OUT

GND M

-12 V

- BATT

SB

-12 TO -48 V


VOICE CHANNEL

SG

M

PTC

BATT

BATT M

D

INT

INT

A

B

C

B






P1

—

A

+

TYPE-IV SIGNALING

IDLE

BUSY

FIGURE C-4. M-LEAD SIGNALING INTERFACE,TYPE IV SIGNALING

C-4

APPENDIX C

TYPE-V SIGNALING


M-LEAD OUT

GND M

-12 V

- BATT

SB

-12 TO -48 V


VOICE CHANNEL

SG

M

PTC

BATT

BATT M

D

INT

INT

A

B

C

B






P1

—

A

+

IDLE

BUSY

N.C

N.C.

GND

FIGURE C-5. M-LEAD SIGNALING INTERFACE, TYPE V SIGNALING

C-5

APPENDIX C


M-LEAD OUT

GND M

-12 V

- BATT

SB

VOICE CHANNEL

SG

M

PTC

BATT

BATTM

D

INT

INT

A

B

C

B






—

A

+

IDLE

BUSY

N.C GNDN.C

IDLE

BUSY

CABLEE

VOICE CHANNEL

M

SB

E

- BATT

SG

TYPE-II SIGNALING BACK-TO-BACK. USING NO EXTERNAL BATTERY.

FIGURE C-6. M-LEAD SIGNALING INTERFACE,TYPE-II (BACK-TO-BACK)

C-6

APPENDIX C

M-LEAD SENSOR (U.K.)

M-LEAD OUT

GND

M

-12 V

- BATT

SB


VOICE CHANNEL

SG

M

PTC

BATT

BATTM

D

INT

INT

A

B

C

B




NOTE: X4 AND X9 MUST BE IN THE U.K. POSITION ON THE UVC AND VOICE II ASP CHANNEL MODULE ONLY.

X2, X6 AND X10 ON EAM-1 PIGGYBACK BOARD IN U.K. POSITION.

—

A

+

IDLE

BUSY

N.C.

GND

SG

E

N.C.

D

- 12 V

X1

X2

X3

15

2

3

8

P1, P2

U.K.OPERATION (SSDC5A)

FIGURE C-7. M-LEAD SIGNALING INTERFACE, UK OPERATION (SSDC5A)

C-7

APPENDIX D

CELP CIRCUIT VOICE LEVEL TESTING

INTRODUCTION The CELP (Codebook Excited Linear Predictive) module is installed andused in General DataComm multiplexer equipment to provide severaldifferent types of application scenarios. These scenarios range from thesimplest (4-wire) applications to the most complex applications using con-ference networks with analog bridging of tandem CELP circuits.

This appendix requires that you have some familiarity with voicetelephony. In order to make full use of the procedures and guidelines youmay need to refer to other references. One recommended reference whichprovides general background information is

a 3 volume set entitled:

Telecommunications Transmission EngineeringISBN Number 1-878108-04-2

published by:

The Bell System Center for Technical EducationUSA Phone Number (201) 699-5802

You should be able to identify the features used by the equipment beingconnected to the voice module. This information is available from thevendor in the form of technical manuals. In the case where it is notavailable it is necessary to formulate the operating characteristics of theconnected equipment. This appendix provides a relatively simpleprocedure to identify these characteristics.

The contents are arranged into three main sections:

GENERAL COMMENTSOUTLINES OF PROCEDURESDETAILED PROCEDURES

The CELP installer should read the General section, and then select theappropriate installation procedures for each situation. Note that the firstand second sections are outlines of the main procedures and terminologyand do not include all of the details. The third section is used to describethe procedures in full detail.

You are also required to use the manuals provided with the test equipmentto select the correct options to run each test.

D-1

APPENDIX D

GENERAL The CELP module can be installed in TMS-3000, Univ. MM+ V4 orMINIMUX Plus equipment manufactured by General DataComm. TheCELP module is used to provide an end to end (MUX to MUX) voice cir-cuit. VF (Voice Frequency) signals into the CELP module are convertedto digital data and transmitted across an aggregate trunk to a remoteMUX where it is converted back into an VF signal.

The CELP is less forgiving of VF signal overload than the ADPCM mod-ules. When upgrading from ADPCM to CELP what may have appeared towork acceptably for ADPCM may not work well for CELP. Therefore,care must be taken during the installation to insure that the alignment ofthe levels of CELP circuits is done correctly. This appendix explains howto properly align these levels.

Each piece of equipment in a circuit has a nominal interface impedance.This impedance is due to the electrical characteristics of the componentsand wires in the circuits. Varying designs and combinations of equip-ment being connected to a CELP module may present different actualimpedances. The differences in the load presented by the terminalequipment to the CELP vary from installation to installation. Whenmeasuring the VF signal levels, they should be measured using actualloads, especially where hybrids are involved. The use of test equipment toprovide the termination should be avoided when possible. When measur-ing levels using the terminal equipment as the load, it is also veryimportant that you use the meter in BRIDGE mode. Failure to do so causesthe readings to be inaccurate.

To properly install a circuit it is necessary that the ‘LOSS PLAN’ be inplace. The Loss Plan will have to be designed using later sections of thisappendix. A Loss Plan is a means of planning and defining the expectedVF signal levels at all points in a network for future reference. The LossPlan need not be overly complicated; however, it is important that it becomplete. When, in the future, adjustments need to be made for any rea-son, then the Loss Plan must be consulted and levels set accordingly.When installing the circuit, the installer will refer to the Loss Plan. Thiswill allow for proper adjustments at the various adjustment points. Muchof the data used to design this plan should be provided in thedocumentation of the equipment being connected to the CELP. In the eventthat this data is not available, it is necessary to perform tests, specifiedlater in this appendix, to obtain the necessary data.

The reason it is so important that the levels being input to the CELP arenot excessive is as follows: the CELP uses a standard CODEC in order toproduce a digital representation of the input VF signal. This digitalsignal is then run through an algorithm (a mathematical process) whichproduces a low speed message for transmission to the remote CELP. Theprocess used to produce this digital signal takes many of the CODEC’s 8bit samples and creates one sample which is decoded to recreate theoriginal VF signal. The CELP algorithm depends on the constant changeof the samples in order to process the digital signal. When the CODEC’sVF signal input is excessive (overloaded), the digital signal which isoutput from the CODEC reaches a maximum numeric value and ceases tochange. In contrast the ADPCM algorithm used is more forgiving. Ittakes each of the CODEC’s digital samples and creates a smaller sample

D-2

APPENDIX D

to be decoded at the remote end. When overdriven, both modules will notcorrectly reproduce the VF signal input, and the CELP will reproduce alower quality VF signal (due to the larger number of errors in the digitalsignal).

When the data is transmitted across an aggregate trunk, the CELP Voicechannel data bits are bit interleaved in a proprietary format, along withdata bits from other types of channel modules. This means that each 64kHz DS0 channel on a E1 or T1 aggregate could contain bits from manydifferent channels. This makes it impossible for the Carrier provider orinstallation technician to monitor and check levels at any point withinthe CELP circuit.

When testing CELP voice circuits using a 1 milliwatt test tone, the digitalequivalent of a 0 dBm VF signal should appear on the Aggregate trunk indigital format, but the data bits are not contained within any single 64kHz DS0 channel, i.e., if a Voice channel were installed in a TMS-3000node, and the Voice channel’s transmit attenuator and gain switcheswere set for 0 dB, then a 0 dBm 1004 Hz tone injected into the Voicechannel should produce a digital equivalent of the 0 dBm 1004 Hz signalwithin the aggregate bit stream, but the bits will be spread out amongstmultiple DS0 channels of the aggregate trunk. Because of the bitinterleaved technique, the digital signal transmitted from the CELPmodule cannot be monitored on the aggregate trunk by any test equip-ment that is available.

The Echo Canceller in the CELP requires an echo return loss of greaterthan 6 dB measured at the CODEC to function properly. This was also thecase with the VEC-1 on the ADPCM. The terminal equipment must betested to assure that it meets this requirement. It is recommended that theecho return loss be at least 18 dB in order to preserve a margin of safety,although only six dB is required (refer to Echo Return Loss later in thisappendix).

OUTLINES OFSPECIFIC

PROCEDURES

This section of the appendix covers the various aspects of alignment andtheir associated concepts. Since many of the terms used may not befamiliar, a Detailed Reference subsection is presented to provide you withfurther explanation of terms. This section is broken down into subsec-tions as follows:

1. Detailed Reference.

2. 4-wire circuits such as 4-wire phones or 4-wire PBXs. No hybrids pre-sent.

3. 2-wire circuits such as PBXs or telephones, which have to be connectedthrough 2- to 4-wire hybrid converters or term sets.

4. Hoot ‘n holler or shoutdown circuits which are commonly encounteredin brokerage applications. These circuits have speakers at one or bothends.

5. Analog bridging circuits which are used to implement conferencephone networks.

D-3

APPENDIX D

Detailed Reference The following paragraphs provide details on terms and concepts whichare used in this appendix. You should refer to this material for precisedefinitions of terms used throughout the appendix.

ECHO RETURN LOSS(ERL)

Echo return loss is the signal which escapes through the transmit path ofthe hybrid when a signal is being received. The return loss of any hybridshould be at least 18 dB. The CELP is capable of accepting return losses ofas little as 6 dB although this is not recommended.

INSERTION LOSS Insertion loss is the loss from 2-wire side to the 4-wire side of the hybridand vice versa. Many hybrids exhibit a 6 dB insertion loss. Generally,active hybrids are designed to operate at 0 dB insertion loss.

HYBRID

TRANSMIT

4-WIRE

RECEIVE

2-WIRE

Z INIMPEDANCE MATCHING CIRCUIT

036R480DI

TERMINOLOGY It is important to understand some terms and concepts when aligningvoice circuits. Two important terms that come to mind are ‘dBm0’ and‘TLP’. ‘dBm0’ is the signal level relative to the TLP. ‘TLP’ is the level ofa 0 dB tone. This level is used when aligning circuits. when reading thefollowing statements pay close attention to the use of dBm, dBm0 and dB.A Voice channel module operates best when the input is close to 0 dB at theCODEC chip input. Therefore a Voice channel optioned for 0 dB gain orloss on the transmit side, would require that the VF signal (analog) inputto the Voice channel be aligned to 0 dBm, for optimum performance.Therefore the module is said to have a 0 dB TLP or 0 TLP. If 16 dB ofgain were selected, then –16 dB would be the TLP.

A Voice channel optioned for –4 dB (4 dB of attenuation), would require a+4 dBm VF input for optimum performance. If you were asked to inject a–10 dBm0 test tone, you would be correct to inject a –6 dBm signal, since+4 dB VF input TLP would be the 0 dBm level, simply because of the at-tenuation option setting of –4 dB.

D-4

APPENDIX D

An example of the use of the terms (dBm0 and TLP) would be as follows:Picture yourself at a TMS-3000 location, about to test a voice circuit withsomeone else at the other end of the voice circuit. He may ask you to in-ject a 1004 Hz tone at a 0 dB level, so he can check his receive level. Thelevel that you should inject would be a level that will provide a 0 dBmsignal into the CODEC chip of your voice channel module. You wouldthen refer to the information about the terminal equipment and obtain thenominal output level. You would then determine what the coarse and fineattenuation/gain option settings are on the Voice channel module. Thetone would be injected at a level that corresponds to the nominal inputlevel (or TLP). The injected VF signal would be at the 0 dBm0 level.

Bridge A device used for the interconnection of two or morefull duplex voice circuits in such a way as to allowsimultaneous transmission and reception to/from alltermination points on the circuit. The bridge is used toinsure proper level control and impedance matching.

CELP Codebook Excited Linear Predictive. A module manu-factured for use in General DataComm Multiplexers.

CODEC A circuit which creates a PCM code signal from ananalog or VF waveform.

dB The logarithmic unit of signal ratio expressed as a di-mensionless quantity. This does not imply anyabsolute value but instead a related loss or gainbetween two point

Documents

TMS-3000 CELP VOICE CHANNEL MODULE - GDC · OVERVIEW The CELP (Codebook Excited Linear Predictive) Voice Channel Module is an analog voice channel card for the TMS-3000, TMS Compact,