[App_rpt-users] Breaking the keying loop between two half-duplex nodes

Tom Hayward tom at tomh.us
Fri Jul 22 21:42:45 EDT 2016

On Fri, Jul 22, 2016 at 5:35 PM, Tom Hayward <tom at tomh.us> wrote:
> I have two RTCMs. Each are connected to half-duplex link radios tuned
> to two different repeaters. The goal is to temporarily add Allstar
> support to these repeaters so they can be linked for a special event.
> The repeaters each have some audio delay, so when the link radio
> switches from transmit to receive, it receives about 250ms of the tail
> end of its own transmission. This gets fed back to the hub,
> transmitted out the other link, the other link receives its own tail
> and the loop continues--it's ping-ponging.
> Looks like there's a setting to fix this:
> http://docs.allstarlink.org/drupal/node/162
> But it's a feature of the URI. How can I do something similar on the
> RTCM / voter.conf?

It's rather hackish, but I fixed the problem by adding 800ms of
hangtime after chan_voter drops the PL:

Index: channels/xpmr/xpmr.c
--- channels/xpmr/xpmr.c        (revision 1536)
+++ channels/xpmr/xpmr.c        (working copy)
@@ -2956,6 +2956,7 @@
                                TRACEC(1,("Tx Turn Off Phase Shift Start.\n"));
+                       pChan->txHangTime+=800/MS_PER_FRAME;


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