Question

With the help of a block diagram, explain the operation of FM superheterodyne receiver.

Answer 1

FM Superheterodyne Receiver: An FM receiver is a superheterodyne type like a typical AM receiver. The functional block diagram of an FM receiver is shown in Figure.
The RF section selects the incoming modulated signals and is simplified. It is then fed into the mixer and local oscillator. Here the frequency of the modulated signal is charged to intermediate frequency. For FM receivers, this IF is $10.7$MHz.
The intermediate frequency wave is amplified using IF amplifier and then its amplitude is maintained constant using a limiter. The output of this section is applied to the FM detector which demodulates the modulated wave. The AF signal from the FM detector is then passed on through a de-emphasis network, where the various frequencies attain their original power distribution. Finally, it is fed into the loud speaker after performing AF amplification.