Definition

Noun: - A noise suppression circuit: A squelch circuit is an electronic circuit designed to mute or suppress the audio output of a receiver (like a radio) when the incoming signal strength falls below a certain threshold, typically when it is weaker than the background noise. This prevents the user from hearing constant, annoying static or noise when no clear transmission is present.

Usage

• The primary function of a squelch circuit is to silence a receiver's audio output during periods of weak or absent signal.
• It is a standard feature in communication devices like two-way radios, scanners, and amateur radio equipment.
• Users can often adjust the squelch threshold to determine the signal level at which the audio is muted or unmuted.

Examples

Advanced Usage

• "To break the squelch": This phrase describes the moment when an incoming signal is strong enough to exceed the squelch threshold, causing the muted audio to become audible again. It is often used in radio communications.
  • We waited for hours before another station finally broke the squelch.

Variants and Related Words

• Squelch (verb/noun): The core action or function performed by the circuit. As a verb, it means to suppress or silence. As a noun, it can refer to the suppression itself or the control knob.
  • Adjust the squelch to quiet the receiver.
• Noise gate: A related audio processing circuit or effect with a similar silencing function, commonly used in audio engineering and music production.
• Carrier-operated switch (COS): A specific type of squelch circuit that activates based on the presence of a radio carrier signal.

Synonyms

• Muting circuit
• Noise suppressor circuit
• Quieting circuit

Related Technical Terms

• Threshold: The preset signal level that triggers the squelch circuit to open or close.
• RSSI (Received Signal Strength Indicator): A measurement often used by squelch circuits to determine signal strength.
• CTCSS (Continuous Tone-Coded Squelch System): An advanced squelch system that uses sub-audible tones to control when the receiver unmutes, allowing communication only with stations using the same tone.

Noun

1. an electric circuit that cuts off a receiver when the signal becomes weaker than the noise