M3SR Series 4100 Selecting the Squelch Type
3.140 Operating Manual 6175.4760.02 – 01
3.7.2.5 Selecting the Squelch Type
Softkey Softkey Type Description
Listbox
If the squelch function is activated, the squelch 
symbol changes from
1. Press 'Squelch' softkey.
2. Select desired mode from listbox.
3. Press 'ENT' key to confirm.
Possible values:
 OFF, RSSI, Signal, Syllabic, RSSI & Syllabic, 
RSSI & Signal
Default value:
OFF
to
.
The squelch is particularly effective for F3E, at 
good reception conditions even for other 
modes but A1A, B8E and B7D, where squelch 
would not allow reasonable reception, it is not 
selectable there.
RSSI (Received Signal Strength Indication)
The RSSI squelch opens only if the squelch 
threshold is exceeded (see RSSI Squelch 
Threshold).
Signal squelch
The signal squelch acts upon a variable sub-
tone. Only if the wanted signal contains this 
subtone, which is always transmitted with it, 
will the audio signal be unmuted. If signal 
squelch is selected, a subtone is also added to 
the transmitted signal. The subtones within a 
network should be set to identical values.
 The signal squelch is supported in modulation 
modes F3E, H3E, R3E and A3E, but not in sin-
gle sideband modulations due to their side-
band filters.
 Syllabic squelch
The syllabic squelch enables the audio output 
when syllabic-like signals are detected in the 
reception signal. This squelch method is less 
fading-sensitive than RSSI squelch.
The syllabic squelch is supported in modula-
tion modes F3E, H3E, R3E, +J3E,-J3E and 
A3E.