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[aprssig] APRS RFID reader?

Lynn W. Deffenbaugh (Mr) ldeffenb at homeside.to
Tue Feb 2 13:58:38 UTC 2010


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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