Design of Broadcast
Frequency Modulation
Design of FM Broadcast Systems
ECE 211L Broadcast Engineering Laboratory
A system of modulation where the instantaneous frequency of the carrier and its rate of change varies in proportion to the instantaneous amplitude of the modulating signal.
The FM Broadcast Band
That portion of the radio frequency spectrum from 88 MHz to 108 MHz. The band is divided into 100 channels, starting at 88.1 MHz up to 107.9 MHz. Each channel is 200 kHz wide, designated by its carrier frequency. Co-located stations should be spaced at least Co800 kHz apart to avoid possible interference.
Classes of FM Broadcast Stations
Class-A Stations ClassA station authorized to have a transmitter power no more than 25 kW and an effective radiated power (ERP) not exceeding 125 kW. The minimum transmitter power shall be 10 kW. The antenna height is limited to 2,000 ft. above the average terrain. Class-A stations shall only be allowed in Metro Manila Classand Metro Cebu. Cebu.
1
Classes of FM Broadcast Stations
Class-B Stations ClassA Class-B station shall have an authorized transmitter Classpower not exceeding 10 kW and an effective radiated power (ERP) not exceeding 30 kW. The minimum transmitter power shall be 1 kW. The antenna height is limited to 500 ft. above the average terrain.
Classes of FM Broadcast Stations
Class-D Stations ClassA Class-D station shall have an authorized transmitter Classpower not exceeding 10 W Educational stations shall be allowed to operate with a Class-D license. Class-
Class-C Stations ClassA non-commercial, community station having an nonauthorized radiated power not exceeding 1 kW.
Radio-Frequency Protection Ratios
All classes of FM stations shall be protected to the 1 mV/m or 60 dBu contour. The following ratios provide for the minimum separation between stations and protection of stations from interference:
Frequency Spacing, kHz 0 200 400 R.F. Signal Ratio 60 dBu : 15 dBu 60 dBu : 33 dBu 60 dBu : 80 dBu
Design of FM Broadcast Systems
ECE 211L Broadcast Engineering Laboratory
A system of modulation where the instantaneous frequency of the carrier and its rate of change varies in proportion to the instantaneous amplitude of the modulating signal.
The FM Broadcast Band
That portion of the radio frequency spectrum from 88 MHz to 108 MHz. The band is divided into 100 channels, starting at 88.1 MHz up to 107.9 MHz. Each channel is 200 kHz wide, designated by its carrier frequency. Co-located stations should be spaced at least Co800 kHz apart to avoid possible interference.
Classes of FM Broadcast Stations
Class-A Stations ClassA station authorized to have a transmitter power no more than 25 kW and an effective radiated power (ERP) not exceeding 125 kW. The minimum transmitter power shall be 10 kW. The antenna height is limited to 2,000 ft. above the average terrain. Class-A stations shall only be allowed in Metro Manila Classand Metro Cebu. Cebu.
1
Classes of FM Broadcast Stations
Class-B Stations ClassA Class-B station shall have an authorized transmitter Classpower not exceeding 10 kW and an effective radiated power (ERP) not exceeding 30 kW. The minimum transmitter power shall be 1 kW. The antenna height is limited to 500 ft. above the average terrain.
Classes of FM Broadcast Stations
Class-D Stations ClassA Class-D station shall have an authorized transmitter Classpower not exceeding 10 W Educational stations shall be allowed to operate with a Class-D license. Class-
Class-C Stations ClassA non-commercial, community station having an nonauthorized radiated power not exceeding 1 kW.
Radio-Frequency Protection Ratios
All classes of FM stations shall be protected to the 1 mV/m or 60 dBu contour. The following ratios provide for the minimum separation between stations and protection of stations from interference:
Frequency Spacing, kHz 0 200 400 R.F. Signal Ratio 60 dBu : 15 dBu 60 dBu : 33 dBu 60 dBu : 80 dBu