FREQUENCY MODULATED SOUND CARRIER
The sound waves picked up by the microphones, are translated into electrical voltages by these devices, Fig. 30.20(a), and fed into the control room through individual audio cables. The sound modulated current is amplified to many times its original strength and then conveyed to the transmitter for impressing on the carrier wave. The sound signal could be impressed on the carrier by amplitude modulation (AM). In the 625 line system, the sound carrier is frequency modulated. The difference between amplitude modulation (AM) and frequency modulation (FM) is shown in Fig. 30.20.
Fig. 30.20 Amplitude and frequency ...
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