I have played a bit with squelch parameters and come to some conclusions.
You almost always want a squelch to be set to a low threshold without
false opening on noise, and you want it to close at a even lower setting,
at least if the incoming station is weak.
The parameters available for the SIGLEV squelch are:
(sample values only)
Then we have the other SQUELCH parameters:
Check the man pages to get detail about the different parameters.
I have noticed for a long time that the selection of CARD_SAMPLE_RATE (in
the GLOBAL section), affects the behavior of the SIGLEV SQL. On some
radios I get a very "jumpy" squelch, and I have to set the
SIGLEV_OPEN_THRESH value high to not false open.
The parameter SQL_DELAY is interesting in these configurations. If the
SQL_DELAY is set to zero (=0) each indication will be sent to the LOGIC,
indicating a SQL OPEN, even if it is just one small sample, few
milliseconds. If we instead set the SQL_DELAY to a higer value, the SQL
indication will be sent to the LOGIC after that time. If the SQL is closed
before that time, no indication will be sent to the LOGIC.
I jumpy squelch could be cured...
I have played with this on two RX's here, and it seams to be useful. With
the SQL_DELAY I was able to lower the SQL_OPEN_THRESH and get a stable
Remember, the audio will be cut in the beginning of each transmission by
the time you set SQL_DELAY, but 50-100 ms is probably not noticeble.
Possible to set different SQL_CLOSE_THRESH for weak stations, to hold the
squelch open longer and not cut of the audio.
Also, we are also using a special SIGLEV_DET=TONE type at one repeater
here in Sweden. It is breifly described in the man page (subversion
73s de Gunnar SG3P