chapter  4
6 Squelch
Pages 3

Figure 4.10 VHF radio adjustment points

Aircraft VHF receivers invariably incorporate a

system of muting the receiver audio stages in the

absence of an incoming signal. This system is

designed to eliminate the annoying and

distracting background noise that is present when

no signals are being received. Such systems are

referred to as squelch and the threshold at which

this operates is adjusted (see Figure 4.10) so that

the squelch ‘opens’ for a weak signal but ‘closes’

when no signal is present.