[App_rpt-users] Use 2 nodes to link with repeaters

Ron Morell ron at morell.us
Tue Jan 3 15:16:58 EST 2012

Using a receive on time delay, (/etc/asterisk/usbradio.conf -
rxondelay=20), to prevent a keying loop between the two nodes goes
something like this:

   1. User w7abc keys up repeater 'A' and node 28174 receives the signal
      and sends it out the VoIP gateway to the Internet to node 28210
      which then transmits what it receives from VoIP and repeater 'B'
      keys up and is now linked.
   2. W7ABC finishes the conversation, repeater 'A' stops transmitting,
      node 28174 stops receiving and the audio to the VoIP gateway is
      closed.  Node 28210 does not receive audio from VoIP and so it
      stops transmitting, and repeater 'B' stops transmitting and the
      link is down.
   3. Repeater 'B' does not stop transmitting instantly when node 28210
      stops transmitting, it has a hang time of approximately 1.6
      seconds.  Node 28210 will receive this signal as soon as it stops
      transmitting and send that audio out the VoIP Gateway to node
      28174 which will then transmit and key up repeater 'A'.
   4. This causes a "keying loop" between nodes 28210 and node 28174.
   5. There is a variable called "rxondelay" in
      /etc/asterisk/usbradio.conf that controls when the node receiver
      can send what it receives out the VoIP gateway.  I would expect
      that if 'rxondelay=90' which is approximately 1.8 seconds, that
      this delay would account for the hang time of repeater 'B', but it
      is insufficient.  Through trial and error I have found that
      'rxondelay=200', or 4 seconds, is required to prevent a single
      keying loop.
   6. A 'rxondelay=90' is sufficient to prevent an ongoing keying loop
      that does not end, but it is not sufficient to prevent a keyup of
      node 28174 "one time".
   7. Node 28174 uses a 'rxondelay=60' to account for the repeater 'A'
      hang time.

So this is a mystery that I have not solved.  A 4 second receive on
delay for the link over VoIP is a long time for the repeater users to
work with.  Many replies and short conversations take less time.  This
method of linking is not a real good one, but it is a portable solution
for quick linking repeaters.  Is there something I am missing in the
configurations that would shorten the link timing? 

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