[App_rpt-users] Squelch issue with RTCM and Kenwood

Lee Woldanski ve7fet at tparc.org
Mon May 1 11:11:40 EDT 2017

Hi James,

What firmware are you running in the RTCM's? And are you running firmware
with the "Chuck Squelch" patch enabled?


On Mon, May 1, 2017 at 8:04 AM, James Cizek <james.m.cizek at gmail.com> wrote:

> Hi folks,
> After dozens of trips to the mountains to get all the physical
> infrastructure upgraded and changed out to Allstar/RTCM, I am finally
> getting back to some little cleanup items.
> I've written before on the "squelch crash" issue, and found that once
> things were tuned up, no one really had any issues with it.  We are having
> severe issues with it and I am trying to narrow it down.
> All sites consist of:
> Kenwood TKR750 (or 850 if UHF) repeater.
> Local on-site PC (micro itx PC with Intel Atom D2500 1.8Ghz Dual core CPU
> and 2GB ram)
> Local mikrotik router (RB2011 in most cases, some CRS125)  Except for
> voters, all repeaters are using the DIAL box plugged into the same local
> router as the RTCMs (ie, just about zero network latency)
> Some sites have 1 repeater, some 2, the biggest site has 2 repeaters and 2
> voters.
> Squelch and Diode calibration was done per RTCM manual
> RX level set per manual
> TX level set by generating 1khz tone with "cop 4" command in asterisk and
> adjusting output for 3khz on service monitor.
> All sites are running DIAL, everything is private node numbers and private
> IP space (no network congestion since we aren't sharing with anything else).
> The RTCM is using external CTCSS input from the Kenwood on pin 24 of the
> AUX connector and pin 24 is set to "TOR".
> The squelch crash is usually only a problem on weak signals, or very short
> (kerchunk) bursts.
> I have included a short video showing the problem on a test bench.  The
> video shows the transmit/receive LED on the HT, and the LEDs on the RTCM.
> It's very clear that the receive signal is gone and CTCSS has dropped while
> the transmitter is still held on to transmit the squelch crash.  The video
> shows a clean transmission, followed by 2 crashes simulated with a double
> "kerchunk".  The mountain top repeaters squelch crashes are upwards of 1
> full second of audio after the incoming transmission has stopped.
> I am wondering if I don't have enough CPU on the DIAL box?  Is it possible
> that I just don't have enough to do the DSP processing fast enough?
> Any tips after seeing the video much appreciated.  Thanks!!
> James
> video url:   http://ki0kn.com/wp/blog/
> (please excuse the barely setup wordpress page!!)
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Lee Woldanski, AScT
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