<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Have you looked at Joe, KC2IRV's website? He has done some extensive experimenting with simulcast. I found it helpful.</div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature"><a href="Http://rtcmsimulcast.wikifoundry.com">Http://rtcmsimulcast.wikifoundry.com</a><br><br>Kevin<div>W8KHW</div></div><div><br>On Feb 13, 2018, at 11:10 PM, Jeff Carrier <<a href="mailto:k0jsc.jeff@gmail.com">k0jsc.jeff@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><div>I really hope to be able to confirm this soon. I've been lazy and our 3 sites are 86 miles, 79 miles and 70 miles (in a triangle). One of the 3 is over 11,000 feet elevation. No matter what we've tried so far you still hear distortion in the overlap area(s) even when 1 site is 20 miles out LoS and the other is around 60 miles out non LoS. Everything is linked on a private uW network with very low latency and basically zero packet loss. The transmitters (GE MIII) run about 1hz freq error with the gpsdo attached.</div><div><br></div><div>Sometimes I just wonder if this is just multi-path from the various granite reflectors we have on the front range of Colorado (one of them is Pikes Peak)</div><div><br></div><div>de K0JSC</div><div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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Message: 6<br>
Date: Tue, 13 Feb 2018 20:43:42 +1100<br>
From: Hayden Honeywood <<a href="mailto:haydenph91@gmail.com">haydenph91@gmail.com</a>><br>
To: <a href="mailto:app_rpt-users@lists.allstarlink.org">app_rpt-users@lists.<wbr>allstarlink.org</a><br>
Subject: [App_rpt-users] Simulcast buffer value issue<br>
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<CAC0VLD0-9mc=<a href="mailto:T8BkvMwx6PqWXqtUXCYY2odbjc2ajjDiVLKSBg@mail.gmail.com">T8BkvMwx6PqWXqtU<wbr>XCYY2odbjc2ajjDiVLKSBg@mail.<wbr>gmail.com</a>><br>
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Interesting thoughts Tim... perhaps worth documenting on the wiki?<br>
Even though it was just "in theory", what kind of sync error was it?<br>
Were we talking microseconds or even more?<br>
<br>
I have a receiver on a yagi pointed at a distant simulcasted site. I<br>
have noticed on occasion, I can hear the distant simulcasted site<br>
start to send audio underneath the carrier of the site that is closest<br>
(and strongest to me). The distant site is also the master site, and<br>
has the lowest latency, but I'm talking two words worth of audio is<br>
send before my other site starts sending audio. Once they are both<br>
transmitting, I have not noticed any timing issues (i.e. distortion<br>
etc). I'm not sure if this issue was related to what I posted<br>
previously about the variable audio delay on unkey.<br>
<br>
I'm running app_rpt on a Raspberry Pi using a cut down image we use here in VK.<br>
<br>
<a href="http://vklink.com.au" rel="noreferrer" target="_blank">http://vklink.com.au</a><br>
<br>
<br>
"When simulcasting the audio from all (non captured) transmitters needs to<br>
arrive at the receiver with in an acceptable time frame (80 us). The DAC<br>
theory was that it didn't start sending audio at correct clock cycle every<br>
time. That would cause the audio to be out of sync between RTCMs causing<br>
simulcast distortion.<br>
<br>
As I said, that was the theory. The new theory is that the external clock<br>
source was causing the DAC to trigger inappropriately. I spoke with someone<br>
I met here on the list (Kevin I think its was) who is using a different<br>
external clock and reports perfect simulcast operations"<br>
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