In an FM receiver, what is the function of the discriminator?

In an FM receiver, what is the function of the discriminator?

• A. Converts variations in amplitude to variations in frequency
• B. Converts variations in frequency to variations in amplitude
• C. Filters out noise from the received signal
• D. Amplifies the carrier without modulation

Answer: (B)

In FM, the information is carried by how the carrier frequency shifts around its center, not by changes in amplitude. The discriminator is the demodulator that detects those instantaneous frequency deviations and turns them into a voltage that varies in just the same way as the audio signal. Put simply, the job of the discriminator is to convert frequency variations into a corresponding change in output amplitude (voltage), which is then processed to recover the audio. That’s why the correct idea is that it converts frequency variations to amplitude variations. It isn’t primarily for turning amplitude changes into frequency, it doesn’t serve as a noise filter in that sense, and it doesn’t simply amplify an unmodulated carrier.

In FM, the information is carried by how the carrier frequency shifts around its center, not by changes in amplitude. The discriminator is the demodulator that detects those instantaneous frequency deviations and turns them into a voltage that varies in just the same way as the audio signal. Put simply, the job of the discriminator is to convert frequency variations into a corresponding change in output amplitude (voltage), which is then processed to recover the audio. That’s why the correct idea is that it converts frequency variations to amplitude variations. It isn’t primarily for turning amplitude changes into frequency, it doesn’t serve as a noise filter in that sense, and it doesn’t simply amplify an unmodulated carrier.