<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta http-equiv="content-type" content="text/html; charset=UTF-8"><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta http-equiv="content-type" content="text/html; charset=UTF-8"></head><body style="zoom: 0%;"><div dir="auto">Theoretically any number of protocols could be sent at the same time provided that the number of protocols does not exceed the bandwidth of 16kHz (normal FM transmit bandwidth). But nothing can happen with a second protocol until the first is taken care of and proper documentation is done then a second can't be formed. <br><br></div>
<div dir="auto">Jon KB3OSP<br><br></div>
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<div class="gmail_quote" >On Feb 14, 2022, at 19:37, Scott Miller <<a href="mailto:scott@opentrac.org" target="_blank">scott@opentrac.org</a>> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
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.
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<br> Scott
<br> N1VG
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On 2/14/2022 4:14 PM, Greg D wrote:
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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.
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<br> Greg KO6TH
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Scott Miller wrote:
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On 2/14/2022 12:55 PM, Andrew Pavlin via aprssig wrote:
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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).
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<br> 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.
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<br> Scott
<br> N1VG
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