As a result, the need for a separate mute switch is eliminated. Finally, the tone-key signal is often used to transmit additional information to the receiver. This may include battery voltage, transmitter audio gain settings, transmitter type, and transmitter power level.
Find An Answer Browse our vast Answer database for answers to many common technical questions. Search the Knowledge Base What is "Squelch" on a wireless receiver? Fields Title. URL Name. FAQ Question. Anything from antennas to external speakers can be found there. What does the squelch do? The squelch quiets the background radio noise when there is no signal present. Simply turn the squelch until the noise goes away. The background noise must be eliminated so the scanner will scan through the channels you have programmed in.
Otherwise it will hang up on a channel and you will only hear the background noise. What does it mean when they say "Go to channel 2"? This should be your first clue that whoever you are listening to uses more than one channel frequency in their operations.
Online frequency listings will show additional frequencies for police, fire and other agencies. Program in all frequencies contained in the frequency lists and you should come up with channel 2 and other channels pretty quickly. Check out National Communications Magazine. What modulation? Turn the squelch control anti-clockwise usually until you hear the hiss, then go back up again until the hiss stops. This is the most sensitive point. If you are troubled with weak stations that you don't want, turn it up a bit more until you get it just right for you, it's whatever floats yer boat!
Joined Jun 6, Messages 2, Depends if scanner or two way radio. Most two way radios have a manual squelch turned by a knob [although more seem to be a menu item]. Plus they also have a RF squelch which can also be set usually by number from "off" up to 15 in some cases. So the higher the number the stronger the signal must be to break the squelch. The scanner I have, has a squelch setting [can't seem to find it right now] but I have it set as low as I could without noise breaking the squelch then set 1 number higher [No 2 is what I use but this may vary according to floor noise or scanner].
This is on Uniden scanners. A typical filter might pass frequencies over 4 kHz. The squelch control adjusts the gain of an amplifier which varies the level of noise coming out of the filter. The audio output of the filter and amplifier is rectified and produces a DC voltage when noise is present. The presence of continuous noise on an idle channel creates a DC voltage that turns the receiver audio off.
When a signal with little or no noise is received, the noise-derived voltage goes away and the receiver audio is unmuted. Tone squelch, or other forms of selective calling, is sometimes used to solve interference problems. Where more than one user is on the same channel, selective calling addresses a subset of all receivers. Instead of turning on the receive audio for any signal, the audio turns on only in the presence of the correct selective calling code.
This is akin to the use of a lock on a door. A carrier squelch is unlocked and will let any signal in. Selective calling locks out all signals except ones with the correct code. In non-critical uses, selective calling can also be used to hide the presence of interfering signals such as receiver-produced intermodulation.
Receivers with poor specifications—such as scanners or low-cost mobile ham radios —can not reject the strong signals present in urban environments.
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