Broadcasting - pidorigy · PDF fileAntenna Polarization Vertical Vertical ... FM BROADCAST...

BROADCASTING Engr. Raymond J. Pidor, PECE

BROADCASTING

It refers to the airborne transmission

of electromagnetic audio signals

(radio) or audio-visual signals

(television) that are readily

accessible to a wide population via

standard receivers.

AM BROADCAST STANDARDS

Parameters Philippine

Standards

International

Standards

Freq. Band 535-1605 kHz 535-1605 kHz

No. of Channels 118 107

BW per Channel 9kHz 10kHz

Permitted BW 30kHz 30kHz

Channel Spacing 36kHz (4 channels

apart)

30kHz (3 channels

apart)

Center Freq Stability ± 20Hz ± 20Hz

Baseband Freq 50-15000kHz 50-15000kHz

Type of Modulation AM AM

Type of Emission A3E A3E

Guardband 36kHz 30kHz

Antenna Polarization Vertical Vertical

Type of Receiver Superheterodyne Superheterodyne

Intermediate Freq 455kHz 455kHz

MAXIMUM POWER ALLOCATION IN KW

Area Low Band

(529-918kHz)

Mid Band

(919-1312 kHz)

High Band

(1313-1705kHz)

Metro Manila 10 20 30

Metro Cebu 10 20 30

Other Areas 5 10 15

AM ANTENNA SYSTEM

Antenna Site Considerations

Location in relation to the population to

be served and to other installations and

airports.

Conductivity of the soil at and

immediately adjacent to the site.

Conductivity of the path between the

site and the target area.

AM ANTENNA SYSTEM

Antenna Design Considerations

The transmitting antenna system shall

be vertically polarized and shall radiate

an effective field of not less than that of

a 60-degree vertical radiator.

The antenna, antenna lead-in, and

counterpoise shall be installed so as not

to present hazard.

AM TRANSMITTER

Transmitter Location and Layout

Considerations

Adequate space

Adequate ventilation and

airconditioning

Adequate lighting

AM TRANSMITTER

Transmitter Design

Parameters Phil. Standards

Carrier Power Limits 10% of Full Power

Max. Modulation for Satisfactory

Operation

85%

Operating Frequency Limits ± 10Hz of Assigned Freq.

Carrier Shift 5%

Carrier Hum and Extraneous

Noise Level

45dB below 400Hz tone

Total Audio Frequency Distortion <5% Harmonics @ 0-84% mod

<7.5% Harmonics @ 85-95% mod

AM TRANSMITTER

Alternate Main Transmitter

Consideration

The regular and alternate main

transmitter to be co-located in a single

place.

Both transmitters shall maintain the

same parameters especially with

regards to authorized operating power,

frequency stability, and etc.

AM TRANSMITTER

Auxiliary Transmitter Consideration

May be installed either in the same

location as the regular main

transmitter or in another location.

Its operating power may be less but

never greater than the authorized

power of the regular main transmitter.

AM BROADCAST OPERATING

REQUIREMENTS

Operating Schedule

2/3 of the total hours that it is

authorized to operate between 6AM to

6PM local standard time.

2/3 of the total hours that it is

authorized to operate between 6PM to

midnight local standard time.


REQUIREMENTS

Program Log Entries

An entry of the time each station identification

announcement is made.

An entry briefly describing each program

broadcast.

An entry showing that each sponsored

program broadcast has been announced as

sponsored.

An entry showing, for each program of

network origin, the name of the network

originating the program.


REQUIREMENTS

Operating Log Entries

An entry of the time the station begins t

supply power to the antenna an the

time it stops.

An entry of the time the program begins

and ends.

An entry of each interruptions.

An entry of the following every 30

minutes: Operating constants and

antenna current.

AM BROADCAST TERMINOLOGIES

Authorized frequency

The carrier frequency authorized by the

National Telecommunications Commission

(NTC).

Carrier wave

A sinusoidal voltage or current generated in a

transmitter and subsequently modulated by a

modulating wave.

Carrier frequency

The frequency of the carrier wave.


Daytime

Refers to that period of time between 2100

GMT – 1000 GMT (5:00AM – 6:00PM local

standard time).

Experimental period

Refers to that period of time between 1600

GMT -2100 GMT (12 midnight -5:00 AM local

standard time).

Intermittent service area

The area receiving service from the ground

wave but beyond the primary service area and

subject to some interference and fading.


Maximum percentage of modulation

The greatest percentage of modulation that may

be obtained by a transmitter without producing

in its output harmonics of the modulating

frequency in excess of those permitted by these

regulations.

Maximum rated carrier power

The maximum power at which the transmitter

can be operated satisfactorily and is determined

by the design of the transmitter.

Nighttime

Refers to that period of time between 1000-2100

GMT (6:00PM – 5:00AM local standard time).


Operating power

The power that is actually supplied to the radio

station.

Percentage modulation (AM)

The ratio of half the difference between the

maximum and minimum amplitudes of the

amplitude wave to the average amplitude

expressed in percentage.

Primary service area

The area in which the ground wave field of

3.16mV/m (70dBu) is not subject to objectionable

interference or objectionable fading.


Secondary service area

The area served by the skywave and not

subject to objectionable interference. The

signal is subject to intermittent variations in

intensity.

Secondary station

A station operating on any one channel and is

designed to render service over a primary

service area which is limited by the subject to

such interference as may be received from a

clear-channel station.


Spurious emission

The emission of any frequency outside of the

assigned channel or authorized band of

frequency and tolerances allowed by these

regulations.

Total harmonic distortion (THD)

The effective value of the harmonic voltages

present in the audio frequency output of the

equipment under test.

FM BROADCASTING STANDARDS Parameters Philippine Standards

Freq. Band 88-108 MHz

No. of Channels 25

BW per Channel 200 kHz

Permitted BW 240 kHz (monophone)

Channel Spacing 800 kHz

Center Freq Stability ± 2 kHz

Baseband Freq 50-15000 Hz

Type of Modulation FM

Type of Emission F3E

Guardband 25 kHz above USB and

below LSB

Antenna Polarization Horizontal or circular

Type of Receiver Superheterodyne

Intermediate Freq 10.7 MHz

Freq Deviation ± 75 kHz (for 100% mod)

Pre-Emphasis 75µs time constant

Pilot Subcarrier

19 kHz

CLASSES OF STATIONS

Station Authorized Power

Class A Not xceeding 15 kW

Class B Not xceeding 10 kW

Class C Not xceeding 1 kW

Class D Not xceeding 10 W

FM FREQUENCY ALLOCATION

Where:

FM = Channel Freq in MHz

FM1 = Freq of the 1st FM Channel (88.1 MHz)

n = Channel Number

BW = Channel Bandwidth (200 kHz)

𝐹𝑀𝑛 = 𝐹𝑀1 + 𝑛 − 1 𝐵𝑊 (𝑀𝐻𝑧)

FREQ ASSIGNMENTS

Channel No. Freq. (MHz)

FM2 88.3

FM6 89.1

FM10 89.9

FM14 90.7

FM18 91.5

FM22 92.3

FM26 93.1

FM30 93.9

FM34 94.7

FM38 95.5

FM42 96.3

FM46 97.1

FM50 97.9

FM54 98.7

FM58 99.5

FM62 100.3

FM66 101.1

FM70 101.9

FM74 102.7

FM78 103.5

FM82 104.3

FM86 105.1

FM90 105.9

FM94 106.7

FM98 107.5

RADIO-FREQ PROTECTION RATIO (IN DECIBEL)

Freq

Spacing

(kHz)

Monophonic Stereophonic

Steady

Interference

Tropospheric

Interference

Steady

Interference

Tropospheric

Interference

0 36 28 45 37

25 31 27 51 43

50 24 22 51 43

75 16 16 45 37

100 12 12 33 25

150 8 8 18 14

200 6 6 7 7

250 2 2 2 2

300 -7 -7 -7 -7

350 -15 -15 -15 -15

400 -12 -20 -20 -20

FM TRANSMITTER CONSIDERATIONS

Construction

The transmitter shall be constructed

either on racks and panels or in totally

enclosed frames protected as required

by the Philippine Electronics Code and

the Philippine Electrical Code.


Enclosure

The transmitter shall be enclosed in a

metal frame or grille separated from the

operating space by a barrier or other

equivalent means.


Grounding of Controls

All external metallic handles and

controls accessible to the operating

personnel shall be effectively grounded.

No circuit in excess of 150V shall have

any part exposed to direct contact.


Interlocks

All access doors shall be provided with

interlocks which will disconnect all

voltages in excess of 350V when any

access door is opened.


Bleeder Resistors

Proper bleeder resistors or other

automatic means shall be installed

across all capacitor banks to lower any

voltage which may remain accessible

with access door open, to less than 350V

within 2 seconds after the access door is

opened.


Wiring and Shielding

Wiring between units of the

transmitter, with the exception of

circuits carrying radio frequency

energy, shall be installed in conduits of

fiber or metal raceways for protection

from mechanical injury.

All instruments having more than

1000V potential to ground shall be

protected by a cage or cover.

FM STEREO BROADCASTING

Two audio channels (L & R) are mixed to provide

two new signals.

The first is the sum of the two input channels

(L+R), and the second is the difference of the two

(L-R).

The sum channel is modulated directly in the

Baseband assignment between 50 and 15kHz.

The difference signal is DSBSC modulated in the

23 to 53kHz slot about a stereophonic Subcarrier

of 38kHz.


Parameters Philippine Standards

Pilot Subcarrier 19 kHz ± 2 Hz

Stereophonic Subcarrier 38 kHz (2nd harmonic of Pilot

Subcarrier)

Stereophonic Subcarrier

suppression level

<1% modulation of the main

carrier

BROADCAST TRANSMISSION SERVICES

Studio-to-Transmitter Link (STL)

Stations in this service are to be used for relay of

aural programming materials from studio to

transmitter and between fixed facilities in other

locations.

Remote Pickup Broadcast Stations

Stations in this service are to be used for the

transmission of aural programming materials and

associated cues and data.

Communications, coordination, and control links

FM BROADCAST TERMINOLOGY

Antenna Height Above Terrain (HAAT)

It is the height of the radiation center of the

antenna above the terrain 3 to 16 km from the

antenna.

Antenna field gain

It is the ratio of the effective free space field

intensity produced at 1.6 km in the horizontal

plane expressed in mV/m for 1 kW antenna

input power to 137.6 mV/m.


Antenna power gain

It means the square of the ratio of the rms free

space field strength produced at 1.6 km in the

horizontal plane, in mV/m.

Center frequency

It is the average frequency of the emitted wave

when modulated by a sinusoidal signal.


Crosstalk

An undesired signal occurring in one channel

caused by an electrical signal in another

channel.

Effective Radiated Power

It is the product of the transmitter power and

the antenna power gain of the antenna field

gain squared.


Field Intensity

It is the electric field intensity in the

horizontal direction.

FM stereophonic broadcast

The transmission of a stereophonic program by

a single FM broadcast station utilizing the

main channel and stereophonic subchannel.


Free space field intensity

It is the field intensity that would exist a

point, in the absence of waves reflected from

the earth or other reflecting objects.

Frequency swing

It means the instantaneous departure of the

frequency of the emitted wave from the center

frequency resulting from modulation.


Main channel

The band of frequencies from 50-15kHz which

frequency modulate the main carrier.

Multiplex transmission

It means the simultaneous transmission of two

or more signals within a single channel.


Pilot subcarrier

It serves as a control signal for use in

reception of FM stereophonic broadcast.

Service area

It refers to the area bounded by a field

intensity that is equal or greater than the

minimum value necessary to permit a desired

reception quality in the presence of noise and

interference, and from which the RF

Protection Ratio is extended


Stereophonic separation

It is the ratio of the electrical signal caused in the

right or left stereophonic channel, to the electrical

signal caused in the left or right stereophonic

channel, by the transmission of only a right or left

signal.

Stereophonic subcarrier

Broadcasting - pidorigy · PDF fileAntenna Polarization Vertical Vertical ... FM BROADCAST...

Documents

Transcript of Broadcasting - pidorigy · PDF fileAntenna Polarization Vertical Vertical ... FM BROADCAST...