Art wrote:

> Hi All,
>
> I need a cheap and very high false positive motion sensor. PIR is a
> disaster, 10 GHz rf based goes through walls and floors which also
> produces false positive alarms.
>
> I read on the web that some are using optical mouse chips, refitting
> them with suitable lens. However, all of these uses are for detecting
> movement _if the entire field of vision changes_........
>
> What I want is a home security type optical detector, which indicates a
> positive if only _part of the field of view changes._ This means the
> sensor is stationary and it would detect a person walking from left to
> right or top to bottom, even though the majority of the field of view
> from the sensor doesn't move.
>
> I need a portable low power solution, not a PC type solution. The sensor
> could be low resolution, a 100 pixel by 100 pixel image (or maybe even
> 50 pixel by 50 pixel) pixel image at 4 frames per second is more than
> adequate. Battery operation is preferred and small physical size is
> preferred.
>
> An optical mouse chip with 18 by 18 pixels might be suitable-not sure
> without testing it.
>
> Can this be done on a tight budget??? Does anyone know of firmware that
> might be used to scan each image and determine if motion has been detecte=
d?
>
> Appreciate any and all input.

If you don't have need to detect the direction of motion just
compare the image frame to frame and count the number of
changed pixels and set a threshold.

It would mean you would need a one frame buffer but very little
processing.

One low cost possibility is 2K cell phone camera and use every
10 to 20 pixels and rows.

w..


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