VanLUG Email Archive
Costco in Richmond (Vancouver, Canada) are selling a security camera kit
for about $145 CAN, for which you get a 250,000 pixel 1 lux monochrome
camera with built-in microphone and infra-red passive motion detector,
a control unit comprising a power supply, VHF pass-through modulator and
buzzer, plus a load of cable. The camera can be a a reasonable
distance from the control unit, and I think the composite video (or VHF)
output can drive a goodly distance again, The salesman told me that the
alarm chime came throught the TV audio, but it doesn't - the control box
chimes.
So what's this got to do with computers ?
Well, I opened up the control box and bypassed the motion-operated switch,
so that the motion sensor signal is independant of the video (normally,
the video is switched off if the motion sensor is enabled until it sees
something). I fed the motion sensor signal (TTL, basically) into DCD on my
serial port, the video output to my Bt848-based video card (about $100)
and the audio into my soundblaster. With "bttvgrab" I have a black/white
webcam, while a daemon based on "powerd" monitors the motion sensor and
launches a script when it is triggered. I've also played around with doing
frame comparisons with Imagemagick "combine" but it eats CPU doing that
with files and pipes. Currently the frame compare is used to reject some
motion-sensor triggered frames.
The webcam may be seen at http://daviel.ml.org/script/webcam/640
A typical triggered frame may be seen at
http://daviel.ml.org/moves/981016.145057.PDT.jpg
Further cameras indoors would be less prone to false triggers, and the
system could be monitored over the net. You'd probably need a good UPS to
do this seriously, and you'd have to make sure the data was uploaded
promptly in case the PC was stolen :-7
(One can get naked cameras from e.g. DigiKey for about $120-ish; probably
the same model as is inside the Home Sentinel unit. There's a colour one
and a monochome one. The colour one generates output like
http://www.triumf.ca/web1_advax/ISAC-current.html)
enjoy
Andrew Daviel
http://vancouver-webpages.com/andrew
Deniable unless digitally signed.
