I sent this to a guy well known who makes widgets for linking via Allstar mode etc:
"I see you do a lot of custom work for repeater controllers, xxxxx etc. There are a lot of folks linking repeaters for GMRS and there is a lot of controversy (linking legal or not?) about the interference created when a distant linked repeater is activated causing potential interference on the channel local to the distant repeater.
As the convention and rules of GMRS require monitoring the channel, this cannot happen when the distant repeater(s) are on a different channel or geographically blocked and is activated remotely.
I have been suggesting to the community a solution that is present on some DMR repeaters and that is logic which listens to the repeater input 467 MHz side, and senses if a mobile or portable is talking (carrier detect) which lacks the valid tone or code to activate the (linked) repeater (IE a foreign repeater user). A "politeness timer".
This would simply be a couple of timers, the first to integrate a few seconds of carrier, the second to hold off the remote keying (Via IP or other link) of the repeater for a period of time 15 to 30 seconds so that local traffic can continue. There would be logic to override this timer if a valid mobile were accessing the repeater. The CTCSS tone detector would be the validating signal. The first timer could be set up so that if over two seconds there is sufficient pulses of carrier, the "politeness timer" would engage. This integrating period would accommodate weak portables at the 50% reliability contour.
I am throwing this out for your consumption as you make a lot of gadgets for repeaters and perhaps this can be incorporated into one of your products via hardware or software and marketed to the great unwashed GMRS linking population to make their systems less annoying., perhaps avoid the wrath of FCC by being proactive. "
