Balancing your VHF radio’s squelch
“The only thing a witch cares about is squelching children.” So wrote children’s author, Roald Dahl. When it comes to marine VHF transceivers the key thing we care about is squelching background noise without losing the radio transmissions we need to listen to.
What is squelch?
The squelch control is arguably the most important of any on a VHF radio. In scientific terms it acts as a noise gate to cut the ever-present background radio noise generated by atmospheric activity and man-made sources. With the squelch fully off (usually fully anticlockwise on a rotary knob or zero or one on a display), you’ll hear the constant hiss and crackle of all of that radio activity. If you left the set like that for any length of time you’d soon be tempted to turn the volume down or even switch the radio off.
The Squelch function allows you to filter out this constant white noise. To activate, start with the squelch control at it’s lowest setting, then turn it up until the point where the noise has just disappeared. The set should be silent except for broadcasts that are stronger than the background radio activity, enabling you to hear those transmissions much more easily.
Hit the sweet spot
Squelch is a simple control but a degree of finesse is needed in use. Normally you should be looking to operate squelch at the sweet spot just a little above the background noise. Often this will be quite low on the control itself, the equivalent of a 2-3 on a scale of 10.
If you turn the squelch up too high, you will considerably restrict what radio traffic you can receive. This might be handy if, for example, you are trying to focus on highly localised strong radio messages, but do remember to reset the control afterwards.
Check to see how the squelch control works
On some modern VHF transceivers, like the Simrad® RS40-B, the volume and squelch controls are combined, with an option to toggle between both functions. If you find yourself on a boat with a different VHF set to the one you are used to, always check to see how this important control operates and ensure it has been set correctly.