What is the difference between squelch and noise blanking in a receiver?

• A. Squelch mutes audio when signal below a threshold; Noise blanking reduces impulse noise to improve readability
• B. Squelch boosts audio when signal is weak; Noise blanking increases noise floor
• C. Squelch filters out high-frequency components; Noise blanking reduces DC offset
• D. Squelch and noise blanking are the same function

Answer: (A)

The main idea here is that squelch and noise blanking serve different problems in a receiver. Squelch mutes the audio when the received signal is below a preset threshold, so you don’t hear steady hiss or noise when there’s no usable signal. Noise blanking, on the other hand, is fast-acting suppression of short, impulsive noise bursts; it temporarily blanks or attenuates the signal during those spikes to keep the wanted signal readable. They work in different parts of the reception chain and address different types of interference, so the correct description is that squelch mutes audio below a threshold and noise blanking reduces impulse noise to improve readability. The other options mix up the effects (boosting audio, increasing noise floor, or filtering DC/high frequencies) or treat them as the same function, which isn’t accurate.