<div dir="ltr">Something to be wary of regarding "channel sharing":<div>The Kenwood TM-D710GA, even with the TNC "shut down", will still digipeat ax.25 packets with a path of TEMPx-y</div><div>This is a feature.</div><div><br></div><div>When I'm running VARA FM through the 710 with the TNC shut down, eventually the ax.25 decoder gets sufficiently</div><div>"confused" that, once the TNC gets set to APRS mode packet decode degrades to the point where I need to do</div><div>a reset (and a configuration reload) to restore full packet decode.</div><div><br></div><div>So having multiple protocols going might not be receiver neutral.</div><div>Craig/KH6CP</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Feb 14, 2022 at 3:07 PM Andrew Pavlin via aprssig <<a href="mailto:aprssig@lists.tapr.org">aprssig@lists.tapr.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div style="font-family:"Helvetica Neue",Helvetica,Arial,sans-serif;font-size:13px"><div></div>
<div dir="ltr">That is assuming both channel-sharing protocols use the same modem tones and data link framing (which APRS and OpenTRAC can do). Something like M17 couldn't share the channel because it uses a different modulation and framing scheme, so a Bell 202 tones/HDLC/AX.25 receiver would only recognize the M17 signal as interference (and vice versa).<br></div><div><br></div>
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On Monday, February 14, 2022, 07:37:44 PM EST, Scott Miller <<a href="mailto:scott@opentrac.org" target="_blank">scott@opentrac.org</a>> wrote:
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Yes, the receiving device wouldn't even know the protocol until it
gets the packet and verifies the FCS and checks the protocol ID.
Regardless of whether the device is using a SQL/COR signal, VOX, or
the modem's carrier detect it's still going to register as being in
use. Some digis might be ignoring carrier detect and transmitting
over packets, but that's a configuration issue.<br clear="none">
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Scott<br clear="none">
N1VG<br clear="none">
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<div id="gmail-m_-9117770001777326072ydpb8fa1978yiv1654347879yqtfd80404"><div>On 2/14/2022 4:14 PM, Greg D wrote:<br clear="none">
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Will stations on the channel that are not dual-mode recognize the
"other" traffic as "channel occupied", or just transmit over the
top and kill the packet? That would be my worry, devolving to
Aloha utilization levels or worse.<br clear="none">
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Greg KO6TH<br clear="none">
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<div>Scott Miller wrote:<br clear="none">
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<div>On 2/14/2022 12:55 PM, Andrew
Pavlin via aprssig wrote:<br clear="none">
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<div dir="ltr">You can't practically run
both protocols on the same RF channel because it wastes
channel bandwidth on signals some (single-protocol)
stations can't understand. We have enough problems with
collisions and hidden transmitters without making it worse
with doubled transmissions from the same stations. Plus,
there are some digipeaters that can't handle two AX.25
frames back-to-back (i.e., one APRS, one OpenTRAC).</div>
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I disagree. The added on-air time isn't nearly as bad as a
doubling since the modem is already locked and everything. Yes,
some digipeaters might not handle it, but you can put the
OpenTRAC packet second if that's not your primary protocol and
you'll only lose the less important one, and you can work on
modernizing the network as you go.<br clear="none">
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Scott<br clear="none">
N1VG<br clear="none">
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