Subscriber question:
"Student pilot here. I am confused about the difference between squelch and VOX and what is the best way to set them?" —Andrew R.
David:
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A few definitions will help clarify how these controls work and the best way to set them.
Radio squelch is a circuit function that silences a radio’s audio output when no strong signal is present. This mutes the background static or noise you’d otherwise hear all the time you had that radio tuned. VOX stands for Voice-Operated eXchange. It activates the airplanes intercom when someone speaks. Without VOX, you’d hear background noise over the intercom even when no one was speaking, or have to press some kind of button to speak over the intercom.
All modern radios have automatic squelch to eliminate background noise and static, so the radio is silent unless a radio transmission is being received. However, Automatic squelch can be deactivated (usually by pushing or pulling the volume knob). This is handy for setting the volume after you initially turn on a radio when no one happens to be transmitting right then. It’s also useful when trying to hear to weak or broken transmission, like an ATIS message when you’re still far away from the airport. Although you’ll have to put up with some static as you listen.
Most modern audio panels with integrated intercoms have auto VOX, so you get silence on the intercom between speaking when the airplane is relatively quiet, like idling on the ground, and in flight when it’s much noisier. If you have a manual VOX setting, you may have to adjust this yourself for different levels of cabin background noise.
A strategy for setting volume levels is also important. Start by setting your headset to maximum volume. Then set the radio volume to a comfortable level, followed by setting the intercom slightly quieter to reduce the chance of missing a radio call. You can fine tune the intercom volume with the dedicated intercom volume control for your position, if available, or by adjusting your headset volume.
