Radio Squelch setting tutorial

Keith Pickersgill

I am constantly surprised that so many pilots do not understand what the Squelch setting on their two-way radio does or how to set it properly, so here goes a mini tutorial:

The purpose of the Squelch is to mute the speaker/headphones when there is no signal being received, to save you from listening to static noise and to save the radio batteries.

When the Squelch level is set correctly, the receiver will be silent until the radio receives a signal from another radio, then the speaker un-mutes in order for you to hear the call.

The higher your Squelch setting, the stronger the incoming signal must be in order for you to receive it.

If you set your Squelch to high, you could mute some weaker radio calls and will not hear them.

If you set your Squelch level too low, the constant static noise in  your ears will affect your ability to concentrate and causes stupid mistakes to be made in flight.

The appropriate Squelch level depends on the ambient RF (Radio Frequency) noise conditions, which varies from place to place and from time to time.

It should be set at the start of every flight, or at least checked that it is not too high.

How to set your Squelch:

First, set the radio to the frequency you will be using for takeoff.

1) Turn the Squelch down (anti-clockwise on the dial, or the down-arrow, depending on brand/model of radio), until you hear the static noise.

At this stage, you can use this noise to adjust your volume control, saving you from asking someone to give you a radio check for the purpose of setting your volume.

2) Now gradually turn the Squelch up until it just mutes the speaker and the radio goes silent (if no-one else is transmitting on this frequency).

3) Now start your engine and during the warm-up, listen to see if the increased RF noise from your ignition system opens the Squelch (the speakers emit Static Noise again). If this happens, increase the Squelch just enough to mute the speakers again.

4) You might find that when you switch on your GPS or camera or other electronic device, your Squelch opens again, in which case you increase the setting again just enough to kill the static.

Once you have an idea of how much you need to increase the Squelch to compensate for engine, camera, GPS, etc, then in future, Do step (1) above, then increase it by that amount (rather too little than too much).

In flight, once everything is on, you can check the squelch by adjusting it downwards and the Squelch should open immediately, indicating that you had the correct level.

If you set the Squelch too high, which is the dead lazy thing to do, you might miss some critical radio calls which impacts on your own safety and that of other aircraft.

Note: Your squelch setting has absolutely no affect on your transmitting, your microphone or how others hear you over their radio.

It affects only the receiving audio.

The next time someone tells me their radio is causing lots of interference in the air and it turns out to be merely their squelch setting was too low and they were listening to static noise the entire flight, expect a kick up the backside!

Listening to static noise in flight affects your ability to concentrate, causes headaches, and causes your hearing to eventually shut down,  so you do not hear when others call you.

Its not a difficult thing to get right.  Read this tutorial again if you are not sure.

If you still do not understand, now is the time to ask...