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[aprssig] Vicinity Tracking

Robert Bruninga bruninga at usna.edu
Thu Sep 9 14:45:31 UTC 2010


> Hi all, tell my kids how to properly configure 
> the tracker without using GPS(no GPS) 
> show examples, thanks!

I was not following the thread.  But any TNC or tracker that
transmits a periodic beacon can be tracked all across the
country without a GPS.  But only to the nearest town or city or
so.  This is because you can use the "vicinity" tracking feature
of APRS to see what was the Digipeater that the device first
used most recently.

This is very powerful, because without the GPS, a few AA
batteries and a low power tracker can operate for a year or more
by sleeping in low power mode for 9.99 minutes out of every 10
and then only waking up to send out a packet (not a position
packet, but a Status or other APRS packet) once every 10
minutes.

You can either check their position manually by looking at the
packet and the PATH used or FIND.COM has a special CGI
"&vicinity" that will plot a map of the last digi that heard it.

Hopefully all of the other APRS sites such as APRS.FI and
Oaprs.net have it as well.

This Vicinity tracking was fundamental to the original APRS as a
means of identifying somewhere on the planet the source of a
packet that entered the APRS system.  With a global system like
APRS, it is nice to be able to locate any packet (even without a
position report) to a given digipeater footprint...

Bob, Wb4APR





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