[App_rpt-users] Squelch tail elimination

[Jon Rorke]

If you are using the Dial or ACID distros, then you can set your node to 
usbradio.

When set to usbradio a sw squelch can be used. The SW squelch has a fast 
squelch for 20 db quieting signals and a slow squelch for noisy signals. 
it mimics the Motrola smart squelch action and works very well. No need 
audio squelch delay.

In usbradio.conf, set carrierfrom=dsp and rxdemod=flat.

Connect your radio discriminator to the URI/FOB RX audio input.

Restart asterisk to load the new config.

Then at the cli do a full alignment for the RX audio,

Do a radio tune rxnoise (with no rx signal on the receiver)
Do a Radio tune rxvoice (with a 1K tone @ 3k deviation with full 
quieting signal in receiver)
and radio tune save.

Then do a radio tune rxsquelch to see the current setting of the sw squelch:

AST_2249_XCN*CLI> radio tune rxsquelch
Current Signal Strength is 799
Current Squelch setting is 500
AST_2249_XCN*CLI>


Set you squelch to about the current signal strength +50 as a rule of 
thumb.

Set the squelch to 850:

radio tune rxsquelch 850

radio tune save


AST_2249_XCN*CLI> radio tune rxsquelch
Current Signal Strength is 799
Current Squelch setting is 850
AST_2249_XCN*CLI>

Test the squelch setting to see how it works.
Repeat above squelch command as required to set squelch to taste.

Then once you are happy with the squelch level, do a final save

radio tune save


If you have to use simpleusb then you are stuck with the logic from the 
radios cor/cas.

In which case the rxaudio delay may work. I dont know if it works on 
Acid or DIAL but looks like its implemented in other images.

Someone may be able to elaborate more on that set up.

Cheers!

Jon VA3RQ








On 8/8/2016 1:18 PM, Tom Hayward wrote:
> I'd like to add some audio delay to get rid of a nasty squelch tail. I
> figured this would be easy, but the documentation is rather sparse.
> Reading mailing list archives, I've found mention of an rxaudiodelay
> or rxsquelchdelay parameter for usbradio.conf. Haven't seen anything
> similar for simpleusb.conf. Searching for actual documentation of
> these parameters hasn't turned up anything. Do they exist? How do I
> use them? Is there another way?
>
> Nothing here:
> http://docs.allstarlink.org/drupal/search/node/rxaudiodelay
> http://docs.allstarlink.org/drupal/search/node/rxsquelchdelay
> nor here: http://docs.allstarlink.org/drupal/node/73
>
> I did find some mention in the code...
> Toms-MacBook-Pro:astsrc-1.4.23-pre tom$ grep rxaudiodelay -R asterisk/channels
> Toms-MacBook-Pro:astsrc-1.4.23-pre tom$ grep rxsquelchdelay -R asterisk/channels
> asterisk/channels/chan_pi.c: int rxsquelchdelay;
> asterisk/channels/chan_pi.c:        M_UINT("rxsquelchdelay",o->rxsquelchdelay)
> asterisk/channels/chan_pi.c: tChan.rxSquelchDelay=pvts[i].rxsquelchdelay;
> asterisk/channels/chan_usbradio.c: int rxsquelchdelay;
> asterisk/channels/chan_usbradio.c:
> M_UINT("rxsquelchdelay",o->rxsquelchdelay)
> asterisk/channels/chan_usbradio.c:
> if(o->rxsquelchdelay>RXSQDELAYBUFSIZE/8-1)
> asterisk/channels/chan_usbradio.c:
> ast_log(LOG_WARNING,"rxsquelchdelay of %i is > maximum of %i. Set to
> maximum.\n",
> asterisk/channels/chan_usbradio.c: o->rxsquelchdelay,RXSQDELAYBUFSIZE/8-1);
> asterisk/channels/chan_usbradio.c: o->rxsquelchdelay=RXSQDELAYBUFSIZE/8-1;
> asterisk/channels/chan_usbradio.c: tChan.rxSquelchDelay=o->rxsquelchdelay;
>
> But it's not much to go off. Looks like I would at least have to
> switch from simpleusb to usbradio to test it?
>
> And in the changelog here there mention of audio delay for squelch
> tail elimination:
> http://www.crompton.com/hamradio/BeagleBoneBlackAllstar/
> "BBB V1.2.2 - simpleusb Channel Driver update to eliminate echo on
> repeaters, added pre-emphasis and audio delay squelch tail
> elimination, fixed phone and web transceiver codec problem"
>
> But again, I haven't been successful in matching this to source code
> or documentation. I have the app_rpt SVN repo downloaded. Where can I
> find the Crompton code fork? (Is it a fork?)
>
> Tom KD7LXL
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