ELFT 533 – Broadcast Engineering and Applied Acoustics
Broadcast Engineering
Broadcasting
Radio Broadcast Station
- one which produces programs and broadcast them to the general public
Types of Broadcast Station
1. AM Broadcast Station
2. FM Broadcast Station
3. International Broadcast Station
4. TV Broadcast Station
Amplitude Modulation Broadcasting
AM BC Band
International Standard:
Philippine Standard:
AM BC Channel Width
International Standard:
Philippine Standard:
AM BC Station Spacing
AM BC Receiver IF
Type of Emission
AM BC Frequency Tolerance
AM BC Antenna
Service Area for AM BC
1. Primary Service Area
- area in which the ground wave field of 1 mV/m is not subject to objectionable fading.
2. Secondary Service Area
- area served by the skywave and not subject to objectionable interference but the signal is subject to intermittent variations in intensity.
3. Intermittent Service Area
- area receiving service from the ground wave but beyond the primary service area and subject to some interference and fading.
Parts of a Broadcast Day (Hours of Operation)
LOCAL GMT
1. Daytime
2. Nighttime
3. Experimental Period
Classification of Powers
1. Operating Power
- is that fed to the antenna by the transmitter
Methods of Measurement
a. Direct Method
b. Indirect Method
2. Maximum Rated Carrier Power
- Is the maximum power at which that model of transmitter can be operated satisfactorily.
3. Plate Input Power
- is the product of the plate voltage and plate current of the final amplifier during the time when no modulation is being applied.
Examples:
1. An antenna has a feed-point resistance of 36 ohms, and the antenna ammeter at the feed point reads 17 Amperes. What is the operating power?
2. A class C final amplifier is plate modulated, where the plate voltage is 4000 V, plate current is 1.563 Amperes and efficiency is 0.8 What is the output power?
Types of Transmitters
1. Main Transmitter
2. Alternate Main Transmitter
- co-located in a single place
- same power and frequency stability
Uses:
3. Auxiliary Transmitter
- may be installed in the same location as the regular main transmitter or in another location.
- Operating power shall not be less than 10% of the operating power of the main transmitter
Uses:
Antenna Tower
Location of Antenna Site
The main considerations in the selection of antenna site are:
1. Location in relation to the population to be served and to other communications installation and airport.
2. Conductivity of the soil at, and immediately adjacent to the site.
3. Conductivity of the path between the site and the target area.
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ELFT 533 – Broadcast Engineering and Applied Acoustics
Block diagram of an AM broadcast transmitting station including STL and remote pickup transmitter. Remote-control lines shown dashed.
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