[App_rpt-users] Kerchunk filter or equivalent of pulseback timer?

[Stephen Rodgers]

Ramesh Dhami (VA3UV) wrote:
> Hi All;
> 
> One of the local repeaters is connecting to the VE3TNK HUB (#2200) using 
> an off-site link radio (since there's no IP at the repeater site).
> 
> Unfortunately, the analog repeater controller can not be set for zero 
> hang time, and therefore the short hang time is being exposed to the hub 
> and all of the downstream nodes.
> 
> Is there a kerchunk filter or the equivalent of a pulseback timer (as 
> there is in IRLP) to compensate (filter out) such kerchunks?
> 
> Thanks!
> 
> Ramesh.
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> 

Something may not be described clearly enough, but what I read out of it
is that you have a dedicated downlink radio from the IP-less repeater
site on a different frequency than the repeater output. When you say
"link" this is what I believe it mean.

For a dedicated downlink channel separate from the repeater controller,
you should be able to have zero hang time by bypassing the controller
entirely and just retransmitting what comes in on the repeater input on
the downlink transmitter from the remote repeater site. This is how I
implement systems on remote sites without IP connectivity.

If you are just using a simplex radio on to talk in to the repeater,
then you are not implementing a link, you just have a radio interfaced
to an app_rpt port tuned to the repeater pair. (Note: I try to
discourage people from doing this it is just not a good way to engineer
a communications system-- Your radio can jam the repeater input and
cause problems for emergency traffic. Link traffic should be uplinked
and downlinked on a dedicated link frequency to avoid this)

All of that said, there is a new config option in the chan_usbradio and
xpmr sources (rxondelay) which will hold off the COR recognition when
PTT is de-asserted by the app_rpt port. I believe the units are
milliseconds, but since Jim Dixon implemented this he would know best.
This is  meant for simplex radios which assert or glitch COR during the
transmit to receive turnaround time but if the delay is made long enough
it could be used to filter out the hang time on the repeater output.

Steve
WA6ZFT