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[aprssig] UI-view add-on for RFID?

Robert Bruninga bruninga at usna.edu
Sat Feb 20 00:31:17 UTC 2010


> But is there anything converting the raw 
> data to something that is useable for APRS 
> yet? 

Not yet. The working reader is only one day old.  And today it
changed significantly.  I removed the 9v stand-alone battery (<5
hrs life) so now the reader is powered form the TNC and will be
on line forever now...  See the updated design:
www.aprs.org/aprs-rfid.html

Lynn Deffenbaugh has volunteered as of today to begin to take a
crack at a temporary central server...  Once someone writes a
stand-alone or adds it into existinc clients then the central
server will be turned off so that duplicates are not generated.

It does not have to be in all user systems by any means.  Just
one copy has to be in the LOCAL area where one or more LOCAL
RFID HotSpots are located.  That one copy of the central
processor will serve that area and when those packets get to the
APRS-IS, then the world.

> There would at least have to be a way for 
> a callsign to be entered the first time a 
> new RFID card was used. 

See the web page.  All any user has to do is send an APRS
message on the national APRS channel and ALL systems globally
will see that and capture the tag-to-callsign association
(including the local one)..  The message is TO RFID and the
message simply has the 10 digit tag number and checksum
ddddddddddkk.

> However, what happens when the card holder goes
> somewhere else where there's an "APRS card 
> reader" and it is used.  Without some central 
> server to remember the association with the 
> card, it would have to be associated with the 
> card again, by something.

Each such local server should be watching the global APRS-IS and
capturing ALL associaitons heard anywhre on the planet.  Since
the fully associated packet that appears on APRS each time the
card is detected, contains both the call and tag number, these
associaitons can continue to be assimilated everywhere.  But we
do need a central clearing house so that at any time, anyone can
"boot up" a new local server by "downloading" a complete list.
This central file server would also have a utility for merging
in files from anyone anywhere.  Associations are only added,
they are never taken off the list.

> I think to be doable as you are describing it, 
> the card reader and "processor" would have to 
> be tied together, whether they were local
> to each other or not.

Either by serial port or by RF.  The rule has to be that nothing
will generate a final assimilated user RFID Position report
directly into the APRS-IS unless (and only if) the HotSpot DOES
NOT  react to RFID raw data on the APRS-IS, and DOES NOT
TRANSMIT onto RF and IS HARD CONNECTED to this "server".

> What would really make the whole thing more 
> workable would be if there was a way of 
> programming a card so it contained the callsign
> of the card holder.

We've been looking for that solution for years, and all of the
longer range cards and programmable cards are too expensive.

> I know you are trying to do this with low cost
> off-the-shelf equipment, but for it to really 
> take off, you might smart cards instead of one 
> that just contained a hex identification code.

I agree, but my experience is that nothing that is a new-start
in ham radio takes off unless it is something the home-brewer
can do at low cost.  So this low-cost $2 approach will get
things rolling, and then as demand builds for more applications
and longer range and programmabliity, then I am sure the
smart-cards will find their way into the APRS system too.

> http://en.wikipedia.org/wiki/Contactless_smart_card

Bob, WB4APR




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