I used a RayMarine C80 to display the targets, but I also had AIS output
available to my laptop. The C80 would display a "no AIS" alarm when I was
in fringe ares where a single ship's signal would fade in and out. This
caused the alarm to keep going off and there's no way to disable this.

If your own vessel has AIS would that silence the alarm? Of course then you
clutter up your display with your own vessel. Would the Raymarine units be
smart enough to know to ignore it's own vessel's signal?

If it can handle seeing it's own vessel then that'd take care of the 'no
AIS' alarm. Or at least make it a way to failsafe it's own signal.

-Bill Kearney