[aprssig] Re: "Emergency!" test convention?

Robert Bruninga bruninga at usna.edu
Wed Jul 21 16:33:31 EDT 2004

Regarding Emergency Beacon Testing:

The need for Emergency Test periods is on systems 
that do not transmit anything *except* emerge4ncy beacons
and are fixed freuqency.  Thus, there is no way to know 
a real one from a test one.

On APRS however, an ermergency message is simply just
another message.  And messages can be tested at any time.
thus no need for any special test period.  Just send a non-test
message any time and it will be propogated like any other
APRS message.  If you want to see how a particular
software handles an emergency, then simply QSY to a
non APRS frequency, send and recive he emergency
message and observe.  When satisfied, return to APRS.

de WB4APR, Bob

>>> "KC2MMi" <kc2mmi at verizon.net> 7/21/04 10:07:07 AM >>>
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
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
activating them and of course, one can't just do that at random
calling wolf.

So may I suggest adding a small point to the APRS spec? From two and
minutes before the hour, to two and a half minutes after the hour,
hour, that five minute period be set aside for emergency beacon tests.
signal received in that window will be treated as a test to be ignored.
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
i.e. from the hour to five past, that you'd prefer to synchronize with,
don't mind at all.)

The alternative is bringing equipment into a faraday cage or sticking a
over the antenna, etc, and none of that quite allows everything to be
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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