Long ago I played with a BC-6 flight monitor. It could not detect realtime glitches on our PCM system. Instead, it had to be set up as I described in my post above. It counted failsafe hits.
The BC-6 Instructions:
http://members.rogers.com/meneer/ynt...stallation.htm
When I had a scope on my old PCM Rx and I could not detect glitches, no matter how hard I tried. However, I was only looking at pulse widths. I did not carefully observe the pulse rate. I think that might be where the magic could happen.
If the period between good frames is slightly different than while in the corrupted frame mode, then a glitch detector could be designed to work. Even a couple microseconds difference would matter. Perhaps the Jomar unit capitalizes on this?
If I still had a PCM Rx I would perform some measurements. But I sold my PCM stuff awhile ago. So Harry, can you measure this for us? Keep in mind that microsecond difference may be in order.
It would be interesting to get some real data from measuring the outputs of the various PCM Rx brands. Their exact behavior all depends on the software design.