[aprssig] "Emergency!" test convention?

KC2MMi kc2mmi at verizon.net
Wed Jul 21 10:07:07 EDT 2004

Bob, either I've missed something when reading the APRS specs, or there's a
glaring omission in them. It would seem that there is no test period
specified for actually testing an APRS unit beaconing the "Emergency!"

What I mean by this, is that many distress systems put aside five minutes
every hour, and during that five minute period anyone that needs to test a
system--test it under actual conditions--is free to do so. Stations
receiving the emergency beacon will ignore it during that period. The
purpose is simple, there's really no way to test emergency beacons without
activating them and of course, one can't just do that at random without
calling wolf.

So may I suggest adding a small point to the APRS spec? From two and half
minutes before the hour, to two and a half minutes after the hour, every
hour, that five minute period be set aside for emergency beacon tests. Any
signal received in that window will be treated as a test to be ignored. Any
signal continuing after that period, or sent before it, would be treated as
a real emergency signal of course. (If there is a different quiet period,
i.e. from the hour to five past, that you'd prefer to synchronize with, I
don't mind at all.)

The alternative is bringing equipment into a faraday cage or sticking a can
over the antenna, etc, and none of that quite allows everything to be tested
as it really will deploy--including reception in the APRS system.

Or, as I said, did I miss something and is this already addressed?


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