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[aprssig] APRS RFID reader?

Wes Johnston, AI4PX wes at ai4px.com
Tue Feb 2 14:20:39 UTC 2010

That's what I was getting at with glitching the power on hte "other"
reader.  If you get a reading from one reader, you make darned sure the
other one can't talk.

I walk up to the outside of the EOC and pull the door open.  While I'm
standing in the magic spot, the outside door mat reads my ID.  It starts
sending serial data to an attached (presumably dumb tnc).  At the same time,
it inhibits either the power on the inside mat or the serial data out.  As I
cross the indoor mat, it reports nothing.  When I leave the building I hit
the indoor mat first, it reports and inhibits the outside door mat for a few

I just looked on the sparkfun website, and they have glass modules that
would easily be slipped inside the rubber inners of my shoes for $5.  I'd
like to keep my RFID device right next to my shoe phone.  Unfortunately, the
read distance is only 10mm.  Even the button ID tag has a 32mm range...  The
credit card format seems to have the greatest range. :-(


On Tue, Feb 2, 2010 at 08:58, Lynn W. Deffenbaugh (Mr) <ldeffenb at homeside.to
> wrote:

> Richard Amirault wrote:
>> Easy ... if you are not there .. and you trigger the sensor .. then you
>> *are* there.
>> If after you are there .. you once again trigger the sensor .. then you
>> are *not* there.
> Not so easy.  Miss one update and the state is then reversed.  S/He's there
> when gone and gone when there.   And then you say, but put a timeout on it.
>  A person will never be there longer than 12 hours....Oh wait, there's 24
> hour contests, ok, so force them to be gone after 24 hours....Oh wait, they
> might move in to the station to staff a hurricane for 2-3 days, so we'll
> time it out in that time....Oh wait, this person is a hard-core station user
> that comes and goes every other day, so s/he'll be perpetually in the wrong
> state.
> I do RFID systems professionally.  If your reader's can't give you
> direction of motion, there's no 100% reliable way to infer such information.
>  Any such inference amounts to an assumption of some kind and we all know
> what happens when we AssUMe.
> Lynn (D) - KJ4ERJ - Recloaking for this discussion
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God help those who do not help themselves.
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