[op25-dev] rx.py Airspy MASTER GAIN Setting option?????

Graham Norbury gnorbury at bondcar.com
Sat Sep 5 12:45:04 UTC 2020

If you're using rx.py try setting "--gain-mode 0" on the command line.
That parameter is not implemented in multi_rx.py but if you change it in
one app (e.g. gqrx), it will persist in other apps until you power cycle
the airspy dongle.


On 9/5/20 8:25 AM, Graham Norbury wrote:
> This happens when the agc is turned on.  Bill Becks and I experimented
> with it a while back and found a way to enable/disable, but at this
> moment I don't recall the magic incantation.
> Graham
> On Sat, Sep 5, 2020, 7:23 AM <op25 at zellners.com
> <mailto:op25 at zellners.com>> wrote:
>     Quoting Graham Norbury <gnorbury at bondcar.com
>     <mailto:gnorbury at bondcar.com>>:
>     > I'm not aware of a master gain parameter.   LNA, MIX, IF are the
>     three gain
>     > controls.  All take value between 0-15.
>     >
>     >>
>     >> ./rx.py --args 'airspy' -N 'IF:10,MIX:5,LNA:15' -S 2500000 -f
>     >> 774.55625e6 -v 7 -T P25PC.tsv -q 2 -V -2  -U -x 2 2>> airspy.log
>     I reran my tests on this again, using -N 'IF:,MIX:,LNA:' like above 
>     with 0-15 values.
>     The spike for the CC, as a test, didn't budge at all, all 15, or 
>     anything in between, no changes.
>     It is significantly lower to start -20 to -40db lower v. other 
>     programs and depending on antenna.
>     Its almost like the gains are set to 0 or something and never 
>     change??? ? ? ? ?
>     Even using a duck direct to the Airspy with another program
>     results in 
>     much higher signals on its spectrum, and gains will adjust
>     accordingly.
>     Changes will occur in another program with adjustments to all 3 
>     (outside its faked single slider mode, using just the REAL GAINS), 
>     gains shows changes in the signals and noise floor.
>     In op25, not a bit of change at all in any thing. noise or signal. 
>     Like these are not being sent? Or not taking affect?? ? ? 15 for
>     all, 
>     combos of values, even things like 50 for all three, no changes.
>     I am not sure what to even try at this point? Other than missing lib 
>     when it was compiled??? I didn't have the airspy then or airspy 
>     pacakges installed when compiled.. does that change anything??? It 
>     seems to work regardless of that, it tunes, it will trunk, voice
>     etc., 
>     just the gains don't seem to do a thing at all. IF there was
>     something 
>     missing in this, I would expect it to fail to tune, audio etc..
>     Ideas?????

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