"Peter L. Peres" wrote:
>
> Try infrared challenge/response. 5 meters is a problem with RF because it
> goes through walls and you can have serious problems with this (hint:
> building level/storey height is abt. 3-3.5m, your 5m range will reach up
> and down beyond that ;-) ).
>
> Peter

Good point, I didn't think of that.

What I need to do is detect a human presence in a range of up to 10
meters max. The person would be in line of sight.

It would be ideal if the 'target device' is passive (ie. requires no
batteries).

Possibly something as simple as fluorescent (or similar) strip(s) sewn
into a garment that can be 'seen' by a detector. The only problem is the
different lighting situations.

--
Best regards

Tony

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