Question
What is the term for the suppression in an FM receiver of one signal by another stronger signal on the same frequency?
Answer Options
- A) Desensitization
- B) Cross-modulation interference
- C) Capture effect
- D) Frequency discrimination
Correct Answer: C
Explanation
FM (Frequency Modulation) receivers are known for their ability to prioritize and lock onto the strongest signal when two signals are present on the same frequency, effectively suppressing the weaker one. This is a desirable characteristic unique to FM systems that helps maintain clear communication in congested areas.
This phenomenon is called the Capture effect. When the stronger of the two signals on the same frequency is about 3 \text{ dB} to 5 \text{ dB} greater than the weaker one, the FM receiver’s limiter and discriminator circuits essentially ‘capture’ the stronger signal. The weaker signal is almost entirely eliminated from the receiver’s output, allowing the operator to hear the dominant signal clearly.
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