What is Combination Squelch Circuit?
Advanced products like the FMR-1000, RE-1 and ENG-100 use a combination of tone-code and amplitude squelch to provide maximum protection against errant signals. In this case, the tone squelch works as described in the previous section and when the tone is present the amplitude squelch remains active. If, in the unlikely event, random noise fools the tone detector, the signal at the intended frequency still needs to be high enough to register on the amplitude squelch. The back up amplitude squelch further reduces the chances that an errant signal will cause audio noise while the transmitter is turned off.
