RX audio delay control?

1

Is there a way to delay (or gate) the rx audio somehow, for 100ms or so, to simulate how an audio delay stage works in a traditional repeater control, in order to eliminate squelch tails?

Eric
K2CB

2

The answer, if you're using simpleusb, is no. However, usbradio has the rxsquelchdelay parameter in /etc/asterisk/usbradio.conf, which does exactly this.

Squelch tails really bug me, so I use usbradio on all my ASL3 nodes, after changing all the filters, because I think the defaults are too restrictive in both directions, except the radio-less ones, where simpleusb works better, especially since I use a footswitch, so you'll never hear any kind of mechanical noise when I unkey.
I think there is a github issue about adding rxsquelchdelay in simpleusb.
If you happen to be using an RTCM board with a good, commercial receiver set to flat audio, then squelch tails are pretty much a non-issue.

3

Unless I'm missing something...

Squelch delay is for preventing ping-pong with controller/interface/linking stuff

Audio delay is for squelch crash elimination

4

rxaudiodelay=0
; default value is 0
; rx audio delay for squelch tail elimination.
; Squelch tail delay in 20ms frames. Values range
; from 0 (no delay) to 24 (480ms delay)
; Typical values would range from 5-10 (100-200ms)

5

I believe in ASL3 it's:
rxsquelchdelay = 60 ; delayline in ms carrier squelch tail eliminator

1 Like
6

So rxsquelchdelay is actually a delay in audio, not squelch? If so, seems to be a poor naming choice... Need some clarification from people that know more than me.

7

Not sure - I'll have to dig a bit further. I don't see any references to rxaudiodelay anywhere in the current code.

8

I don't know about old ASL versions, but rxaudiodelay is a HamVoIP thing, available in both their version of simpleusb and usbradio, and it is a value in frames, not MS like rxsquelchdelay in usbradio, which is not part of simpleusb in ASL3. rxaudiodelay in HamVoIP serves the same purpose as rxsquelchdelay in ASL3/usbradio, which is to insert a delay line to truncate X MS of audio at the end of a transmission, which can effectively eliminate squelch tails from radios sent to the node.

9