Acoustic Treatment of the Studios (Repaired)

Technological University of the PhilippinesAyala Boulevard, Ermita ManilaCollege of EngineeringElectronics Engineering Department

AM BROADCAST DESIGN

Submitted to:Engr. Luna A. Dela Cruz

Submitted by:

Rolando Y. Morante, Jr.

BS ECE 5C

05-207-066

2nd Semester, S.Y. 2009-2010

Technological University of the PhilippinesAyala Boulevard, Ermita ManilaCollege of EngineeringElectronics Engineering Department

February 27, 2010

Engr. Luna A. Dela CruzECE Faculty This University

Sir:I am pleasured to present the design entitled "AM Broadcast System design" in compliance for the requirements as a partial fulfillment of the course ECE 15L (Broadcast Engineering and Acoustics, Laboratory). The study on AM Broadcast System will underscore its fundamentals and applications.This covers the development of an AM Broadcasting Station from studio onto the transmitter to be located at Tagbilaran City, Bohol.

Very truly yours,

Rolando Y. Morante, Jr.

BS ECE 5C

CHAPTER IIPreface

AM radio broadcasting involves the modification of the amplitude of audio frequency signal received from the microphone. The audio frequency signal and carrier wave may be amplified independently before being superimposed, i.e. modulated, after which they are sent to the antenna. In another method, the audio signal and carrier wave may be modulated and then amplified before being sent to the antenna. In either case, if amplitude modulation is used, the audio waves amplitude is varied accordingly.

It was felt that a well-designed AM broadcast system could significantly improve reception quality, reliability and ease of use and ensure the continued use of AM bands.

To meet these aims, a highly flexible design has been developed. This was made possible with the recommendations from the KBP standards and the Radio Codes that served as guides.

This design is aimed at the management of broadcasting organizations in areas of policy making as well as in programme making and technical planning. It explains the technical considerations needed to take into account in building an AM studio.

CHAPTER IIIAcknowledgment

To Almighty God

To my friends

To my family

To my professors

I am heartily thankful for the encouragement, guidance and support from initial to final level, which enabled me to develop an understanding of the course.

I offer my regards and blessings to all of those who supported me in any respect during the completion of the project.

CHAPTER VITechnical Requirements

Technical Factors Considered in the Site SelectionA. StudioWhen the studio and the transmitter are to be separated to each other, Studio site must be within densely populated areas, or within a city proper. This is facilitating same technical aspects as:

1. Accessibility of the Studio for maintenance purposes2. Nearness of the Studio to the public3. The Studio will be accessible to the studio personnel (announce, technician etc.) as well as guest.

B. StationThe proper selection of the site for the technical station is an essential and exciting task in the planning of any communication system. The cost of the site development and installation of facilities is high and warrants utmost care. Recognizing the factors involved in the correct choices of equipment site is essential in order to avoid costly mistakes resulting to the poor performance or even total system failure. The following are to be considered:

1. In the absence of any local regulations of the contrary locations should be chosen so that for the power and antenna to be used. The following intensities are delivered over the city to which the station is associated.Overall urban parts25 mV/m minOverall suburban parts2 mV/m min2. The site should have the highest soil conductivity for a distance of at least 1mile from the antenna.3. The site should offer a clean path to the city.4. Avoid obstruction at high hills between the antenna and the nearest city to be observed.5. The area of this station should be large enough to close a ground system of about wavelength in radians or as near to this as a local condition with permit.6. Soil should be consistent which will permit suitable footing for the antenna and guy wires without necessary expenses.7. The site should be where the antenna height will not become an obstruction for air traffic.8. Locate the site as convenient as possible after the above conditions are satisfied to the power and telephone lines as well as rail roads or roads and for transportation.9. Avoid a location that requires the same precautions regarding ground system of an antenna as to that flat terrain. There is no advantage electrically to hill topsides for station operating on low and or medium frequencies.10. Avoid locations where there are chances of flooding of any seasons.11. The location should be reasonably flat and above sea level.

Factors Considered in Choosing the Site for Transmitter and Studio

The main considerations in selection of a Broadcast site are:A. Location in relation to the population to be served and to other communication installations and airports.B. Conductivity of the soil at and immediately adjacent to the site.C. Conductivity of the path between the site and the target area.

Before the approval is given for any site, the authority shall refer to existing local and natural regulations governing antenna construction. Restrictions may be imposed on the height and location of masts in certain areas and obstruction painting and/or lighting may be necessary. Except in the area now officially designated as an antenna farm, masts or tower less than 150 feet from the ground in height may be erected and are exempted from this provision. Masts or towers with heights above 150 feet from the ground are normally required to put up the standard obstruction lighting and painting.

A. TRANSMITTING EQUIPMENT

The transmitting equipment and facilities shall be laid out in accordance with good engineering practice, thereby providing ease of maintenance and operation, and safety to personnel.

B. LOCATION AND LAYOUT

The building shall be of a design and type of construction suitable to the area in which it is located and it shall comply with relevant building regulations.1. Adequate space shall be provided in the building to facilitate access to all equipment for operation and maintenance purposes. Adequate space for staff facilities shall also be provided.2. Adequate ventilation and where necessary, air conditioning shall be provided to ensure satisfactory working conditions for staff and equipment.3. Adequate lighting shall be provided in all equipment rooms to facilitate operation and maintenance of the equipment.

C. STUDIO LOCATION AND LAYOUT

1. The building that will contain the studio shall satisfy the provisions given in section of these standards.2. Each studio shall be associated with a control room from which the operational area of the studio may be viewed with ease. The authority may, however, approve an operation whereby the studio and control rooms are integrated into one and that responsible personnel shall perform simple font panel type functions like level adjustments and switching during his/her board hours, provided, a licensed ratio technician with a 1st, 2nd or 3rd class radio telephone licensed is employed to perform all the more complicated pre and post sign on adjustments of a more technical nature including maintenance jobs which are necessary for the proper operation of technical studio equipment. Provided further, that this kind of operation, an automatic program level control is employed to ensure that a proper program level is fed to the transmitter.3. Studios and control rooms shall be constructed that they are adequately insulated from sources of extraneous noise and vibration, and the acoustic treatment of such studios and control rooms shall be in accordance with good engineering practice.

Location Plan of Studio and Transmitter

A. For StudioBuilding should be located in an area of the metropolitan district where the following conditions could best to met:1. Zoning restrictions must permit type of building required and permit erections of tower on site.2. Sufficient land for the erections of a two-storey building and room for future additions or expansion.3. A site location approximately in the geographical center of the metropolitan area to be served by the television signal.4. Attractive frontage.5. Land of reasonable valuation, but with good prospects for future developments.

B. For Transmitter SiteStep 1:Select a frequencyYou may operate on any AM frequencies that do not interfere with a licensed operator.

Step 2:Survey onsite listeningSurvey the streets and roadways where listening is required with an automobile digital AM radio tuned to your candidate frequencies. Monitor all the candidate frequencies throughout the listening area at least once during daylight hours and at least one after dark. Note which frequency appears to be quietest when monitored.

Step 3:Choose a general location for coverageUse a map to select a general antenna location such that a signal-radius circle fully encompasses the streets, parking lots and other areas that require coverage. If a geographic area is critically important to cover, consider locations near the center of that area. Mark the map to show the area within which the antenna should be located to meet your coverage goals.

Step 4;Consider the installation styleInstall the transmitter and flexible antenna system in a building to produce coverage in the vicinity of a building.The transmitter may be located in the building or in a weatherproof cabinet at the base of the pole or tower. The same power considerations above will apply. The coaxial cable that connects the transmitter to the antenna may be one of the following length ranges: 0 25 ft., 75 200 ft. and 250 400 ft.

Remote Audio ModulesIf you will be controlling audio by telephone, a telephone line must be accessible at the transmitter location.

Step 5:Consider equipment, options and servicesReview the price sheet, options and services.

Step 6:Preparing your transmitter siteYou can get ready for installation by preparing your transmitter location. This preparation is detailed in the Installation Instruction Manual and includes 3 steps:1. Equipment Operating LocationFor building-oriented stations, this means identifying the equipment operating location in the building. For isolated-style stations: installing the equipment cabinet at the transmitter site.2. Installation of Power and Telephone ServicesFor building-oriented considerations, this means making sure the 120 VAC power and a (optional) shielded-line telephone service are present/installed at the equipment operating location in the building. For isolated style stations: installing power and shielded telephone line to the equipment cabinet.3. Prepare the Antenna Support SystemFor Roof-Style stations, this includes identifying or setting up a antenna-support system on the building roof and running coaxial cable to the equipment operating location in the building. For Yard and Isolated-Style stations includes setting the pole to support the antenna.

C. Transmitter Technical Aspect

1. The locality must be reasonable flat and free from screening hill angles, buildings and elevated structure in the neighborhood.2. It must be reasonable above sea level and must not be subjected to dampness or liable to water lugged.3. It must be reasonable to have suitable contours soil conductivity, particularly near the site.4. On the standpoint of the foundation for the mass of the building, the best site must be the bottom, it is little below the best site surface point. The areas of this shape of the land to be acquired are govern by the building code up to the extent of the grounding system.

In the absence of local regulation of the country. Location should be chosen for the power and the antenna to be used. The following intensity to be delivered over the city to which the station is associated.Overall urban parts 25 mV/m minOverall suburban parts2 mV/m min

ECONOMIC ASPECT CONSIDERED IN THE SITE

A. Studio1. The site must be near a road to make it accessible.2. It should be near the power line and water supply.3. The site is not critical.

Since the studio is near densely populated area, it gathers income from site and studio goers specially when having live shows. Sometimes this economic signal aspect often gives less attention the technical aspects.

B. StationAfter accessing the physical characteristics of the site favorable to the type of service proposed, the engineer must acquaint himself with the following:1. Building restriction enforced by the local authority.2. Aviation regulations governing the mass.3. The prevailing cost of the land in the locality.4. Cost of preparing the site, concerning erecting buildings.

The important economic issues, which affect the construction on putting into operation of, station area:1. A good road within a short distance of the site in rainy season and all weather conditions. Any bridge along the route must be able or capable of handling the heaviest load to be transported.2. It must be reasonable short distance from the nearest town railways, etc.3. It must be low cost of building materials, skilled workers and means of transporting them into the site.4. Cost electricity derived from the proposed site to which existing power transmission line extends.5. The abundance of fresh water supply at all times.6. Cost of construction and installation of the telephone line between the studio and the transmitter.7. Consideration of highways within the large site and appreciable areas of land bay, the tower beneath the antenna system.8. Cultivated land area must be avoided to the high cost of compensation to the owner.9. The site must be sometimes outside the city for the low cost of the land.

CHAPTER VIISite Description

LOCATION PLANA. STUDIOThe studio is set to be located in the district of Tagbilaran City in Bohol. Particular location of the studio is on the 3rd floor of a commercial building. The studio and its adjacent function rooms will occupy at least one half of the floor area of the third floor.

The location of the studio passed all the most important factors in choosing a site for broadcast studio. The place is very accessible to the public, to maintenance personnel and the studio personnel itself. Being in the heart of Tagbilaran, Bohol, it enjoys an adequate power supply and easy access of water and telephone lines.

The selection of the studio offers very excellent economics plus factors to the building owner and would owner of the station. In addition, the site offers good commercial opportunities. Income from the promotion and advertisement from the nearby commercial establishments should not be discounted.

B. STATION (Transmitter)The transmitting station is to be located in spacious ground of Tagbilaran City, Bohol. It will be house in a one story-building especially constructed for the purpose. The station and the antenna space will cover an approximate area of 2000 square meters of land.

The conductivity of the adjacent soil, area is quite good. The place is not too far with a body of water, fishing grounds and lines of trees as well as rice fields. Basically, the environment within the area shows a very good condition of propagation.

C. SITE DESCRIPTION AND LOCATION

The AM Broadcasting studio and the transmitter station are separated by approximately 3 km. both locations enjoys a good access to supply of electricity, telephone lines of course water because its a town proper or main city of Bohol.

The main broadcast studio will be constructed at the second floor of a commercial building in Tagbilaran City wherein it will occupy about 55% of the floor area of the 3rd floor. Some renovations are to be made to segregate studio room and adjacent facilities from one other commercial store within the building. The transmitting antenna of the STL will be in the roof top of the building.

CHAPTER VIIIDesign Procedures

1. Select the area where the proposed station is to be set up.2. Obtain a list of stations already existing within the area and nearby regions together with their operating power, frequency, class of operation and approximate locations.3. Choose the class operation of the proposed broadcast station, its operating power, operating frequency taking into account all the information obtained from #24. Determine the general shape of area intended to be served and choose a specific site for your antenna.5. Choose an antenna system to fit the general shape of the intended area.6. Determine the inverse field strength at different distances from the antenna taking into account the conductivity of the ground in each and every direction.7. Determine the inverse field strength of one mile from the selected antenna site at the operating power in every direction.8. Draw the field intensity contour of the class of operation and check if it satisfies the requirements of the intended service area, the co-channel, adjacent channel interference and other relative considerations.

Modify whatever system parameter necessary (EG transmitted power, antenna system, antenna spacing, etc.) to obtain a satisfactory design.

From Step 6: Determine the inverse field strength at one (1) mile.

1. Determine the operating wavelength = c / f = Vc / fc2. Obtain the antenna height from the ground entitles (frequency vs vertical height for broadcast station).3. Convert the antenna height from feet to wavelength.4. Determine the effective field strength E from 1 KW for 1 mile, for a simple omnidirectional vertical antenna with ground station at least 120 radials or from the graph entitled Antenna Height.5. Determine the inverse field strength at 1 mile at operating power frequencyEff = Eo sqrt Pt / eachwhere:Pt = operating power in kW when using 2 tower directional antennaEo = field strengthEff = Effective field strength, mV / m

Inverse field strength at one mile from the antennaE = E1 sqrt(2F) sqrt { [ (1 + F2) / 2F ] + cos (Scos + ) }where:E = inverse field strengthE1 = inverse field strength at 1 mile from tower 1 when operating in array, mV/mE2 = inverse field strength at 1 mile from tower 2 when operating in array, mV/mF = E2 / E1, the ratio of field strength from 2 to 1, degrees = azimuth angle from the line of tower, degrees, radial angleS = spacing between tower to tower, degrees = phasing of antenna

Inverse field strength of one mile operating in the arrayE1 = Eo = sqrt { R1 / [ ( R11 + RL1 + RC1 ) + M ( R22 + RL2 + RC2 ) ] }where:E1 = inverse field strength at 1 mile for tower 1 operating alone as standard reference area, mV / mEo = effective field strength, mV / mR11 = Loop resistance at tower 1, RL1 = Loop resistance assumed for tower 1, RC1 = Coupled resistance at loop of tower 1 from another tower while array is in operation, R22 = Loop resistance at tower 2, RL2 = Loop resistance assumed for tower 2, RC2 = Coupled resistance at loop of tower 2 from another tower while array is in operation, M = ratio of current at loop of tower 2 divided by current at loop of tower 1Coupled Resistance Formula:RC1 = Mz cos ( + )RC2 = M / z cos ( - + )Where:Z = magnitude of loop impedance between the two towers, = angle of loop mutual impedance, degrees = electrical phase of current in tower 2 with respect to tower 1, degreesM = magnitude of loop current ratio of loop current in tower 2 divided by tower 1

CHAPTER IXDesign Computations

CHANNEL: 5CALL SIGN: DYKAOPERATING FREQUENCY: 567 kHzCLASS OF STATION: Class BPOWER OUTPUT: 10kW

OPERATING WAVELENGTH ()

*Actual Antenna Height

ANTENNA HEIGHT (m)From Figure 1

hom = 310 ft

ANTENNA HEIGHT IN WAVELENGTH

ANTENNA HEIGHT IN ELECTRICAL DEGREES

h2 = h1 x 360 = x 360 = 65.3433

POWER CLASS Power Class = 10 kW P1 = 0.5Power Class = 0.5*10kw = 5kW

*INVERSE FIELD STRENGTH AT 1 MILE FROM TOWER OPERATING ALONE AS A STANDARD REF. ANTENNA E0 = E * p1/2 E = Effective field strength (mV/m) E = 180 mV/m E0 = 180(51/2) E0 = 402.4922 mV/m

ANTENNA SPECIFICATIONSNo. of Antenna in the System: 2Spacing of the two antenna (); 90Phasing of the two antenna (): 165% Field Strength Radiated in Horizontal Plane from No. I Antenna:63 mV/m from No. 2 Antenna:63 mV/m% RMS Field Strength in Horizontal Plane from Antenna System: 56

DETERMINE THE RADIATION LOOP RESISTANCES R11 = Tower 1 ; R22 = Tower 2 *for identical towers, R11 = R22 From Figure 3: R11 = R22 = 25 DETERMINE THE LOOP MUTUAL IMPEDANCE BETWEEN A/4 VERTICAL ANTENNA From Figure 4: Impedance (Z) = 7 RC1 = MZ*cos( + ) RC2 = (Z/M)*cos( - ) *M is constant Phasing () = 100 Spacing () = 90 M=0.995 RC1 = 0.995*7*cos(90+100) RC1 = -6.8592 RC2 = (7/0.995)*cos(90-100) RC2 = 6.9283

*INVERSE FIELD STRENGTH AT 1 MILE FROM TOWER 1 WHILE OPERATING IN THE ARRAY (mV/m)E1 = E0 *{R11/ [(R11+RL1+RC1) + M * (R22 + RL2 + RC2)]} mV/mE0 = 402.4922 mV/mRL1 = RL2 = 2 (Assumed Loop Resistance)E1 = 402.4922 *{25/ [(25 + 2 + (-6.8592)) + 0.995*(25 + 2 + 6.9283)]} E1 = 274.1166 mV/m

COMPUTING FOR THE RADIANSE = E1 * (2)1/2 * {1 + cos[ (cos( + ))]} = 90 = 165

For the Graph:E0 = 14.5155E15= 14.1421E30= 14.5155E45 = 15.5493E60= 16.9942E75 = 18.4776E90 = 19.5882E105= 20.0000E120 = 19.5882E135 = 18.4776E150 = 16.9942E165 = 15.5493E180 = 14.5155E195 = 14.1421E210 = 14.5155E225 = 15.5493E240 = 16.9942E255 = 18.4776E270 = 19.5882E285 = 20.0000E300 = 19.5882E315 = 18.4776E330 = 16.9942E345= 15.5493By substitution:

E0 = 397.8938 mV/mE15 = 387.6594 mV/mE30 = 397.8938 mV/mE45 = 426.2309 mV/mE60 = 465.8395 mV/mE75 = 506.5014 mV/mE90 = 536.9453 mV/mE105= 548.2332 mV/mE120 = 536.9453 mV/mE135 = 506.5014 mV/mE150 = 465.8395 mV/mE165 = 426.2309 mV/mE180 = 397.8938 mV/mE195 = 387.6594 mV/mE210 = 397.8938 mV/mE225 = 426.2309 mV/mE240 = 465.8395 mV/mE255 = 506.5014 mV/mE270 = 536.9453 mV/mE285 = 548.2332mV/mE300 = 536.9453 mV/mE315 = 506.5014 mV/mE330 = 465.8395 mV/mE345 = 426.2309 mV/m

CHAPTER XGraph, Tables and Contour Mapping

Conductivity Table

TerrainConductivity mV / m

Sea water5,000

Fresh water8

Dry, sandy, flat coastal land2

Marshy, forested, flat land8

Rich agricultural land1

Pastoral, medium hills & forestation5

Rocky land, green hills mountainous hills up to 3000 ft.1

Cities, residential2

Cities, industrial0.5

Contour Mapping

Distance (mi)TerrainConductivity (mV / m)

FromToDistance

At 0

04.00004.0000Rich agricultural land1

4.00004.30770.3077Sea water5000

4.30774.76920.4615Dry, sandy, flat coastal land2

4.76925.53850.7692Sea water5000

5.53858.46152.9231Marshy, forested, flat land8

8.461511.53853.0769Rocky land, green hills mountainous hills up to 3000 ft.1

11.538516.92315.3846Rich agricultural land1

16.923117.69230.7692Sea water5000


18.461520.00001.5385Sea water5000

At 15






At 30


9.692312.30772.6154Pastoral, medium hills & forestation5




At 45






At 60





At 75







At 90









At 105



9.384620.000010.6154Sea water5000

At 120



2.307720.000017.6923Sea water5000

At 135



0.769220.000019.2308Sea water5000

At 150



0.46150.76920.3077Sea water5000


1.230820.000018.7692Sea water5000

At 165



0.30770.76920.4615Sea water5000


2.615420.000017.3846Sea water5000

At 180



0.30770.76920.4615Sea water5000


3.230820.000016.7692Sea water5000

At 195



0.30770.76920.4615Sea water5000


3.692320.000016.3077Sea water5000

At 210



0.30770.61540.3077Sea water5000


5.230820.000010.9231Sea water5000

At 225



0.30770.61540.3077Sea water5000


9.076920.000010.9231Sea water5000

At 240



0.46150.61540.1538Sea water5000


8.923120.000011.0769Sea water5000

At 255



0.46150.76920.3077Sea water5000



6.153820.000013.8462Sea water5000

At 270



0.46150.61540.1538Sea water5000


2.000020.000018.0000Sea water5000

At 285



0.461520.000019.5385Sea water5000

At 300



0.615420.000019.5385Sea water5000

At 315



0.923120.000019.0769Sea water5000

At 330



2.15387.07694.9231Sea water5000



10.461520.00009.5385Sea water5000

At 345


2.30772.46150.1538Sea water5000


6.92317.23080.3077Sea water5000




14.000014.15380.1538Sea water5000


15.384620.00004.6154Sea water5000

CHAPTER XIIAcoustical Treatment of the Studio

A. Control of Room ResourcesA room with good acoustics is essential to recording and mixing your music correctly. "Good acoustics" can be defined as getting the sound from the speakers to your ears as unchanged as possible. A good home studio room should be as neutral as possible while still having some life to enable you to hear detail (such as stereo positioning) properly. This ensures that music you have mixed and equalized to sound good has the best chance of sounding good in other rooms. Controlling the sound in a room is achieved by selective acoustic treatments. Once again, let me stress acoustic treatment is not soundproofing - it does not stop sound from getting in or out of the room, it controls the characteristics of sound within the room.

These are the common problems which you need to fix to make your room conform to the ideal listening environment mentioned above:

Room ReverberationWe home reccers are often at a disadvantage as we are working in relatively small rooms with parallel walls, as well as a parallel ceiling and floor. Any sound in a room like this reflects repeatedly backwards and forwards between these surfaces, creating reverberation. You know what this sounds like - we have all clapped our hands in an empty room and listened to the reverb (some of us do this compulsively!). Controlling these reflections is one of the most important things we can do to make the room sound good. For our purposes, the reverberation time (the amount of time it takes for the reverb to die away) should be close to a half second.

Early ReflectionsWhen either the sound source or the listener is close to a boundary or any hard surface, the reflection from that boundary can cause a sound to arrive at the listening point via two paths (direct and reflected) at slightly different times. The two sounds will be out of phase with each other at some frequencies and these frequencies will cancel each other out. Other frequencies will be in phase and these will be reinforced. The resulting frequency response will be very uneven, and the stereo image will also be distorted.

Standing Waves & Dead SpotsStanding waves are created when you have two parallel boundaries (two walls, or the ceiling and floor). Some frequencies are reinforced by the distance between the boundaries (the sound makes exactly one round trip on each cycle of the speaker and the pressure fronts pile up). This is why it's nice to sing in the shower - the low frequencies of your voice are greatly amplified by the standing waves.

B. Treatment of the Work Place

You may be surprised to find that basic sound control of a room is actually quite simple and can often be accomplished with inexpensive materials.

ToolsFortunately, the best tools to measure sound in a room are your ears! Listen to the sound of a room before and after the acoustic treatments listed below by listening to CDs you are familiar with. Vocals and words should be clear, the bass balanced and tight, and cymbals bright without being harsh. A mono signal will seem to come from a spot exactly between the speakers - and that spot should not move with different notes. Clap your hands and listen to the resulting sound - you should hear a slight thickening of the sound, but little reverb - and no definite pitches or echoes.

Monitor Speaker Positioning Everything in the room should be as symmetrical as possible. Monitor speaker placement should be symmetrical within the room - with each speaker the same distance from its closest wall. Putting speakers too close to corners tends to emphasize the bass in an unpredictable way, so place your speakers away from them. Small changes in position can affect the sound quite significantly, so experiment with moving your speakers forward or backwards while your CD is playing and aim for a smooth response, especially at the low end. If some bass notes seem louder than others, move the speakers around until this is minimized. The distance between the monitors should be equal to the distance between each speaker and your ears - forming an equilateral triangle. Avoid strong early reflections from near field monitors (which cause phase interference). Put them on solid speaker stands behind the desk rather than on the meter bridge of a large mixer (this creates an early reflection path off the mixer surface). If you're getting strong reflections from the ceiling above the speakers, consider putting a foam absorber or two up there.

DiffusionYou can break up reverb from flat surfaces by mounting objects called diffusers on them. When sound is reflected off a convex or complex surface, it spreads the reverberant sound evenly throughout a room. This prevents standing waves and also eliminates "dead spots"- where frequencies are drastically reduced or missing. The thicker the diffuser, the lower the frequency that will be affected. One of the best diffusers I know is a deep bookcase well stocked with a variety of sizes of book. A rough stone wall is also quite an effective diffuser.

AbsorptionExcessive reverb and standing waves can be tamed by using materials which absorb sound. These are often fiberglass or particleboard panels, special foam tiles (which often double as diffusers). These generally work well down to 100 Hz or so. Absorption materials need not be expensive. Carpet on a thick under felt, thick curtains with backing and even plush furniture can help reduce reflections. Dont try covering every surface of your room with absorptive material to completely deaden the room. A dead room would be unpleasant to work in, as your ears use the subtle phase differences of a live room to accurately place sound sources in a stereo image. Also, absorptive materials are frequency selective, with high frequency sound being absorbed easier than low. This means that as absorption is added to a room it becomes more and bassier in tone.

Avoid bare walls in the front of the room (behind the speakers). Remember, you want only direct sound from the monitors to reach the listening position. So 80-100% coverage with acoustic tiles or at least some heavy drapes will work wonders. Fix a few square meters of acoustic tiles to the walls each side of the listening position to absorb and diffuse. This will help keep the stereo image nice and tight. Use diffusion behind the listening position, at the rear of the room. This makes the room seem deeper than it really is. We happily use materials which do not absorb well below 100 Hz due to the fact that normal wall and floors are absorptive in the low end, but very reflective above 200 Hz.

CHAPTER VDefinition of Terms

Amplitude modulation(AM)A technique used in electronic communication, most commonly for transmitting information via aradiocarrier wave.

Analog TransmissionThebroadcastingof a signal using an analog recording. Examples of use includeradio.

BandwidthThe available space between two given points on the electromagnetic spectrum and, inter alia, the amount of information that can be squeezed into that space.

BroadcastingThedistributionofaudioand/orvideosignalswhich transmit programs to an audience. The audience may be the general public or a relatively large sub-audience, such as children or young adults.

Call LettersThe official name of the radio station in the Philippines. Also known as a station'scallsign.

CrystalRadio Receiver (crystal set)A very simpleradio receiver, popular in the early days of radio. It needs nobatteryor power source and runs on the power received fromradio wavesby a long wireantenna.CoveragePercentage of households that can tune into a radio station within the theoretical broadcast radius.

DaypartThe radio station's broadcast day is normally split up (starting at 6am) into a series of 4 hour sessions containing one or more shows.

DBS - Direct Broadcasting (by) SatelliteTelevision and radio programmes distributed bysatellitefor reception via adishat the receiver's property.

FeedbackA loud noise produced when the amplified sound from an output (loudspeaker) is picked up by an input (microphone,phonograph) feeding thatloudspeaker.

FCC -Federal Communications CommissionAn independent United States government agency, established by the Communications Act of 1934 and is charged with regulating interstate and international communications by radio, television, wire, satellite and cable.

Ground WaveInradiotransmission, itis a surface wave that propagates close to the surface of theEarth. ITU -International Telecommunication UnionOriginally theInternational Telegraph Union, the ITU is the international organization established in 1865 to standardize and regulate international radio and telecommunications.

Kapisanan ng mga Brodkaster sa Pilipinas(KBP)A broadcast media organizationin thePhilippineswhich provides its members broadcasting standards.

kHz - KilohertzThousand cycles per second. kHz is used to measure mediumwave and often shortwave frequencies.

NetworkA system which distributes programming to multiple stations simultaneously, or slightly delayed, for the purpose of extending total broadcast coverage beyond the limits of a single radio or television signal.

NTSC- National Television Standards CommitteeAn American committiee formed to set the line standard and later color standard for broadcasting. Gave its name to the method of color reproduction used in the Americas (except Brazil) and in Japan.

Positioning statementA radio station's mission statement or vision statement. A one to two sentence statement that conveys what you do for whom, to uniquely solve an urgent need. These are usually aired during Image Liners.

RadiobroadcastingAn audio (sound) broadcasting service, broadcast through the air asradio waves(a form of electromagnetic radiation) from a transmitter to a receiving antenna.

Radio StudioA room in which aradio programor show is produced, either for livebroadcastor for recording for a later broadcast. The room is soundproofed to avoid unwanted noise being mixed into the broadcast.

Radio waveA type ofelectromagnetic radiationwith wavelengths in theelectromagnetic spectrumlonger thaninfraredlight. Naturally-occurring radio waves are produced bylightning, or byastronomical objects

Signal-to-noise ratio(S/N)A measure used in science and engineering to quantify how much a signal has been corrupted bynoise. It is defined as the ratio of signal power to the noise power corrupting the signal.

SkywaveThepropagationofelectromagnetic wavesbent (refracted) back to the Earth's surface by theionosphere.

CHAPTER XVAM Broadcast Standards

CHAPTER IVIntroduction to Broadcasting

CHAPTER XIIntroduction to Acoustics

CHAPTER XVIBrochures

CHAPTER XVIIILicense

CHAPTER XIXPermits, Application Forms and Procedures

CHAPTER XXIIITopographic Map

CHAPTER XXIIRecommendations

Here are the recommendations to be filed for the design of the AM broadcast system in Tagbilaran City, Bohol:

1. The implementation of additional broadcast sites in the growing population of the province.

2. As a provincial radio station it must serve as a medium of development communication, a conduit between the government and the people, aiming to mobilize all sectors of society towards development and nationalism. Live government news must be aired here.

3. For the studio design, cost of materials should be maintained thus improving the acoustical quality of the room.

CHAPTER XXIConclusion

AM radio technology is simpler thanFM radio,DAB,Satellite RadioandHD Radio. An AM receiver detects amplitude variations in theradio wavesat a particular frequency. It then amplifies changes in the signalvoltageto drive aloudspeakerorearphones.

Because of its susceptibility to atmospheric and electrical interference and the generally lower sound fidelity of superheterodyne receivers, AM broadcasting has attracted mostly talk radio and news programming, while music radio and public radio mostly shifted to FM broadcasting in the late 1960s and 1970s.

AM radio signals can be severely disrupted in large urban centers by metal structures, tall buildings and sources of radio frequency interference (RFI) and electrical noise, such as electrical motors, fluorescent lights, or lightning. As a result, AM radio in many countries has lost its dominance as a music broadcasting service, and in many cities is now relegated to news, sports, religious and talk radio stations..

CHAPTER XIIITechnical Specifications

Acoustics

The sound absorption coefficient indicates how much of the sound is absorbed in the material. The absorption coefficient can be expressed as:

= Ia / Ii

where Ia = sound intensity absorbed (W/m2)Ii = incident sound intensity (W/m2)

Total Sound Absorption

The total sound absorption in a room can be expressed as:

A =S11 + S22 + .. + Snn = Sii

whereA = the absorption of the room (m2 Sabine)Sn = area of the actual surface (m2)n = absorption coefficient of the actual surface

Mean Absorption Coefficient

The mean absorption coefficient for the room can be expressed as:

m = A/ S

wherem = mean absorption coefficientA = the absorption of the room (m2 Sabine)S = total surface in the room (m2)

Reverberation TimeRT = KV / A

where:K = 0.16 (m2) = 0.049 (ft2)V = volume

CHAPTER XIVIndoor and Outdoor Safety Rules

INDOOR PLANT SAFETY RULES

GENERAL RULE:

This section establishes safety rules for all electronics and communications equipment installed and/or located inside buildings or in sheltered structures, except consumer products.

5.1.1 SHOCK, CASUALTY or FIRE HAZARD shall not result when normally used and operated

5.1.2 A grounding system shall form a part of all indoor electronics and communication installations failing under any of the following category:

a. When any equipment is powered from 1 10 VAC or higher;b. When an outdoor exposed facility is connected to any equipment for its normal operations;c. All radio stations, telephone/telegraph/telex exchanges and fixed computer installations.

5.1.3 The grounding system shall be designed to direct foreign currents in the shortest route possible to earth.

5.1.4 Potential rise on accessible parts shall be no greater than the values specified in rule.

5.1.5 Strength consideration for indoor equipment installation shall be sufficient to assure that no casualty hazard shall result from falling or collapsing equipment or their5.1.6 Operation of electronic and communications equipment shall not result in emission of fumes, chemicals, radiations, etc to such a level considered hazardous by those recognized by the government to make such assessment.

5.1.7 Users of electronics and communication systems or services shall be protected from shock or fire hazards attendant to the use of the service.

5.1.8 It shall be the users responsibility to ascertain that adequate internal protection is built into the equipment by the supplier in such a manner that no shock or fire hazard shall result when the equipment is operated within its rating.

5.1.9 The electrical protection measures shall coordinate with the inherent dialectic strength and surge current carrying capacity of the equipment or system being protected.

5.2.2 Mobile Station (Land mobile, Maritime mobile, Aero mobile)

This section covers radio transmitters, receiver, transceiver and allied equipment at mobile locations such as:

1. Land Mobile radio installation on board vehicles, like automobiles, trucks, trains, etc, whose movement or travel is confined overland.2. Maritime Mobile -- radio installation on board water crafts, like boats, ships, etc.3. Aeromobile -- radio installations on board aircrafts and spacecrafts.5.3 SWITCHING EQUIPMENT SAFETY REQUIREMENTS (Telegraph, Telephone, Telex, etc.)

5.3.1 Switching equipment is subject to damage from lightning and power fault currents which may be conducted from outside plant cable or wire circuits. A.C operated equipment can be damaged from lightning and switching surges conducted through the electric power lines. To protect personnel and prevent damage to equipment these foreign potential surges shall be effectively limited by application of suitable protective devices.

5.3.2 Surge arresters of suitable type and rating shall be connected on all wire circuits entering the building except on wire lines in all of the following criteria:

1. The entire length is underground.2. Not bunched with a circuit any portion of which is installed above ground level.

5.4 The Computer is the vital nerve center in any EDP installation and prevention of fire shall be the overriding concern.

The signal wiring shall be contained in cable structure with an over all jacket or Polyvinyl Chloride (PVC) or equivalent formulation with equal or better resistance to burning.

Office furniture required in the EDP operations should be of metal construction or other non combustible material contents.

The Computer requires special environmental conditions such as humidity, temperature and dust, making air-condition systems, a vital accessory to operations and shall be given attention as fire prevention.

The condition unit shall be installed in anon-combustible area cut-off from all other areas. If possible the air-conditioning unit for the computer room shall be independent of equipment supplying the other areas in the building.

5.5 STATION SAFETY REQUIREMENT

A station installation for the purpose of this code shall comprise all equipment installed inside customer premises such as telephone instruments, teletype/data, CRT terminals, PABX/PBX, etc either customer-owned or leased requiring a physical line connection to a serving office for its normal operation.

5.5.1 Protectors

5.5.1.1Electrical protection shall be provided for station installations falling under any of the following:a. The line serving the station is partly or filly of aerial plant installationb. The station equipment operates from voltages thru the line in excess of 45 VAC RMS or 135 VDC (telephone ringing voltage not considered)c. Where the station equipment is installed m a bathroom, near a swimming pool, on boat dock or in a boatd. Where any loop served by the station equipment is exposed to lightning.e. Any on-premise extension whose facility could accidentally come into contact with supply voltages must have protection at both ends5.5.1.2Protectors shall be used on station installations falling under any of the conditions in rule 5.5.1 A thru E.

5.5.1.3Protector voltage breakdown rating shall be as low as may be allowed by the circuit being protected

Protector location shall consider the following:a. Must be accessible for maintenanceb. Avoid excessively damp locations and where the atmosphere may be combustibles.c. At least 15 cm away from curtains or draperies.d. At least 30 cm from electric wires, devices or appliances.e. Avoid locations subject to tampering or where materials may be stored or placed against.f. Must be separated by rigid mechanical divider from supply devices and wirings.

5.5.2Grounding and Bonding

5.5.2.1 Customer equipment installation and wiring shall meet rule 3.1.5.

5.5.2.2 Ground wires run shall not exceed 15 m of No.10 or 14 AWG wire free from sharp bends and kinks.

5.5.2.3 Earth grounds shall be selected and used in the following order:a. A public or private water system metallic pipe buried and in contact with the earth for at least 3 m.b. buried extensive metallic pipes or tanks.c. ground rods.

5.5.2.4Ground connections shall not be made to gas, gasoline or oil lines, fuel tanks, power transmissions, hot water pipes, etc.

5.5.2.5 Ground rods shall not be places within 2 m of foreign ground rods.

5.5.3Locations

Special OccupancySpecial protection measures shall be adopted for the following:a. Power generating and sub-stationsb. Flammable material processing storage or loading areasc. Minesd. Trailer Parkse. Radio tower sites

Customer Equipment Safety RequirementsWithout proper protection, subscriber/customer equipment and telephone subsets are susceptible to damage from transient voltage on the telephone lines and may cause shock to the users.The transient voltages and currents in the telephone lines may be caused by the following:a. lightning strikesb. Close proximity of the phone lines to power linesc. Contact with power linesd. The normal operation of the telephone subset

GROUNDING CONDUCTOR SIZE AND TYPE

OUTDOOR PLANT SAFETY RULES

The company you work for as an Electrician probably has a list of safety rules list your employee handbook.Be sure to look over thee rules. Here are some safety rules-

Carry a first aid kit in your toolbox. Maintain all tools in its operating condition. Tag out defective equipment so others will not use them. Avoid hazardous work positions above and below the ground. Use protective gear appropriate to the environment. Clean up work area before, during and after work. Lift heavy materials properly. Seek help as needed. De-energize circuits while making repairs to avoid electric shock. Proper footwear is mandatory.

BETWEEN WIRES, CONDUCTORS, CABLES AND MESSENGERS

INSULATED CABLES are treated as single conductor and therefore no specified clearance is required between the individual conductors of the cable.

The minimum clearance for span wires, messengers, and guys as well as with communication conductors is not applicable to wires, conductors, etc. of the same entity.

Communication service drops crossing below supply conductors of 0-750 volts, or above supply line cables with metallic sheaths where such metal sheath is adequately grounded may have a vertical clearance less than 1.2 meters but shall be less than 0.6 meters.

Where communication conductors cross under or in con collinear with supply conductors of 750 to 7500 volts within 1.8 meters, the vertical clearance shall be increased to not less than 1.5 meters.

For supply voltages over 200,000 volts, the clearance of 1.8 and 2.4 meters shall both be increased to not less than 3.9 meters

On poles which carry no cross arms, open wire conductors attached to the sides of poles by means of hooks, knobs/brackets may be placed on any position with in the 1.0 meters next below the topmost conductor on the pole.

CABLES, MESSENGERS that where attached to the surface of poles which support supply conductors shall not less than 1.8 meters vertically below the level of supply conductors.

For supply voltages over 200,000 volts the clearance of 1.8 meters shall be increased to not less than 1.8 3.9 meters.

The clearance of 0.15 meters is not required between conductors on line arm and related buck arm.

FROM STRUCTURES

The basic minimum clearances of wires, conductors, cables, and messengers from signs mounted on buildings/structures are shown in 7.1 E.

CLIMBING SPACE

CLIMBING SPACE shall be provided on one side/quadrant of all poles/structures supporting communication conductors except at the level of one pair of conductors attached to the pole below the lowest cross arm and the top 0.9 meters of poles carrying communication conductors only which are attached directly to the pole.

The POSITION OF THE CLIMBING SPACE shall not be shifted more thin 90 degrees around the pole within a vertical distance of less than a 2.4meters

VERTICAL RUN RISERS, GROUND WIRES

VERTICAL RUNS OF COMMUNICATION WIRES or cables supported on the surface of wood poles or structures shall be covered by a suitable protective covering within a vertical distance of 0.9 meters above or I.8 meters below unprotected supply conductors supported on the same pole or structure.

RUNS OF BRIDDLED CONDUCTORS attached to the surface of the pole need not be covered provided such runs are below the guard arm and in the same quadrant as the longitudinal cable or where such runs are below and on the same sides of the pole with a cable arm and are not in the climbing space.

RUNS which terminate in the top enclosure which afford ample mechanical protection to the runs may extend within 2.4 meters of the ground but not less than 1 8 meters of the ground without being treated as risers.

RISERS

RISERS OF WIRES OR UNDERGROUND CABLES Shall be encased in securely grounded metal or plastic pipe from the ground line to a level not less than 8 feet above the ground line.

GUYS AND ANCHORS

Where mechanical loads imposed on poles, towers, or structures are greater than can be supported with the safety factors as specified in Rule 4.3.2 under the loading condition of Rule 4.2 additional strength shall be provided by the use of guys or either suitable construction.GUYS shall be attached to structures as nearly as practicable as the center of load.

GUY WIRES shall be protected by the use of guy thimbles when attached to anchors

GUYS attached to or passing poles supporting only communication conductors need not to be sectionalized provided such guys are not exposed or in proximity m supply conductors

Table of Contents

AM Broadcast Design

I. Letter of Transmittal

II. Preface

III. Acknowledgment

IV. Introduction to BroadcastingA. Philippine Broadcast HistoryB. History of AM Broadcasting in the PhilippinesC. AM Broadcasting

V. Definition of Terms

VI. Technical RequirementsA. Technical Factors Considered in the Site Selectiona. Studio (Accessibility of studio for maintenance purposes)b. Station (The cost of the site and installation facilities)B. Factors Considered in Choosing the Site for Transmitter and Studioa. Transmitting Equipmentb. Location and Layoutc. Studio Location and LayoutC. Location plan of Studio and Transmittera. For Studio ( A site location approximately in the geographical center of the metropolitan area to be served by the signal)b. For TransmitterStep 1 --- Select a FrequencyStep 2 --- Survey Onsite ListeningStep 3 --- Choose a General Location for the CoverageStep 4 --- Consider the Installation Style(The transmitter may be located in the building or in a weatherproof cabinet at the base of the pole or tower)Step 5 --- Consider equipment, cost and serviceStep 6 --- Prepare your transmitter site1. Equipment Operating Location2. Installation of Power and Telephone Services3. Prepare the Antenna Support Systemc. Transmitter Technical Aspect(It must be reasonable to have suitable contours soil conductivity particularly near the site)D. Economic Aspect Considered in Site Selectiona. Studiob. Station

VII. Site DescriptionA. Location Plana. Studiob. Station Transmitterc. Site description and locationi. History of the Place and Mapii. Geographic Locationiii. Topographyiv. Industriesv. Support facilities1. Power2. Water3. Transportvi. Social and Economic Factsvii. List of AM Stations in the Vicinity

VIII. Design Procedures

IX. Design Computations

X. Graph, Tables and Contour Mapping

XI. Introduction to AcousticsA. What is Sound?B. Propagation of Sound

XII. Acoustical Treatment of the StudioA. Control of Room ResourcesB. Treatment of the Work Place

XIII. Technical SpecificationsA. Reverberation Calculations TrailB. Design Computation

XIV. Indoor and Outdoor Safety RulesA. Philippine Electronic Code System Rule (Indoor and Outdoor Plant Safety Rules)a. Indoor Plant Safety Rulesb. Outdoor Plant Safety Rules

XV. AM Broadcast Standards

XVI. Brochures

XVII. KBP Standards

XVIII. License

XIX. Permits, Application Forms and procedures

XX. Radio Codes

XXI. Conclusion

XXII. Recommendation

XXIII. Topographic Map

Documents

Acoustic Treatment of the Studios (Repaired)