16 Advanced muting function
This receiver also features AMF (Advanced Muting Function). This special electronic feature comes into effect when an RF signal drops by about 40 dB in a short time. The reception is then muted for at least three seconds. AMF thus suppresses the annoying switch-off click when a transmitter is switched off. Because of the delay in switching on again, the PLL circuit of the transmitter has enough time to adjust itself back to the corresponding transmission frequency.
Example
One possible area of use for AMF is the inaudible change of a hand-held transmitter. If the battery of the first transmitter has run down (display “LOW BATT” on the receiver), a second transmitter is prepared on the same frequency: insert battery, select transmission channel. Then the first transmitter is switched off, AMF switches to mute and the second transmitter is switched on. The PLL of transmitter 2 stabilises itself, AMF switches on again. The whole procedure takes place inaudibly in the background while AMF is switched to mute. Without AMF, the switching off, switching on and stabilising of the transmission frequency would have been audible in the form of possible crackles and whistling noises.
AMF can be switched off. As it is coupled with the setting of the normal squelch, its function is cancelled if the squelch is set to position “0” (see chapter 15).
