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[aprssig] New! SHACK-SPOT RFID

Robert Bruninga bruninga at usna.edu
Sat Feb 20 01:34:03 UTC 2010

HotSpot in your own Shack or Clubhouse...
Wow, it can't get any simpler!

You can simply add a $25 RFID reader to ANY existing APRS
station with no other hardware required (as long as it uses a
standard TNC).  

Just diode-or the output of the RFID reader into the TXD data
line (at 9600 baud) and the data packets from the RFID reader
will be interleaved with  your existing APRS station output.
You cannot be walking in your door at the same time you are
typing packets anyway!  And your station does not even have to
be outputting the special HotSpot position report.  Because the
callsign central server will have defaults.  SO that any RFID
tag number from ANY existing APRS station will by default add
RFID calls in .01 (60 foot) increments
on top of your station call!

So now when you have APRS visitors, we can all see who is in
your shack!

This idea came up as I was permanently installing my coil under
my lab door map and looking around for a spare TNC and Radio and
Power supply...  Duh, I already got that!  Just run the serial
data to  the existing TNC and its DONE!

PROBLEMS:  But so that it doesn't screw up your existing system
we have got to use commands in the TNC to:
1) Change the COMMAND character from ^C
2) Make sure it ignores ending Linefeeds
3) Trap-out the ending ^C

Don't some TNC's have a command where you can tell it to IGNORE
control codes?
This will solve it, but make it difficult to switch between

Bob, WB4aPR

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