BasicB-003-003-007
In an FM receiver, what is the purpose of the limiter?
D
Answer
Basic radio theory
Type
A
Maintain constant input level to the mixer
B
Suppress local oscillator harmonics
C
Prevent overdriving the IF amplifier
D
Remove amplitude variations from the received signal
Answer Notes
In Frequency Modulation (FM), the audio intelligence is conveyed entirely by how the frequency changes, not by the amplitude of the signal. Therefore, any variations in amplitude are essentially unwanted noise, such as static or ignition interference.
The limiter stage is placed just before the detector (discriminator) in an FM receiver. It literally limits or clips the top and bottom of the signal waveform, ensuring a perfectly constant amplitude.
This clipping action removes amplitude variations caused by noise or fading, which is the primary reason FM communications sound so clear and static-free compared to AM.
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In a superheterodyne receiver, which stage provides the final signal power to drive the detector?
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In an FM receiver, what is the purpose of the discriminator?