RE: Re: NOW: PIRs WAS: Stair Mats

[Scott Crowther <scrowther@xxxxxxx>]

> The one huge caveat with PIRs in general is positioning IME, if 
they are
> not positioned correctly then they won't work. By that the I 
include the
> direction they are aimed in, the height and what kind of room/area
they
> are in, often in larger rooms and especially hallways more than one
is
> needed to give reliable coverage. Obviously if positioning is an 
issue
> then the more sensitive you can get the PIR the better.

It's also worth remembering that the more upmarket PIR's have a 
jumper-selectable "hit rate" to improve immunity to false
triggers. 
In occupancy detection situations this is usually the inverse of the 
desired performance...


And wireless PIR's have their own inherent problems with having an
inbuilt
'sleep' 
period from 90 seconds to 3 minutes after initial activation, to save
battery life.

Scott



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