[aprssig] APRS RFID reader?

[Patrick]

I'm  not so sure that it really matters when people are leaving places  
though..  I'd think the idea for this sort of system would be that at  
1323 today I was at the EOC, weather coming or going..  I'd see this  
expiring with a high decay rate, so you could have multiple readers  
through a facility which would feed the network that you're still  
there, but after 20 minutes of no beacon I don't think it would be a  
safe bet to assume people are still there..

That said, I don't believe it should be too hard to come up with a  
design for a 2 stage reader which is able to infer directionality  
based on which order the two readers read the tag, as long as both  
readers do read it of course.

p


Quoting "Lynn W. Deffenbaugh (Mr)" <ldeffenb at homeside.to>:

> 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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