Re: Ultrasonic Sensors

["Crash Gordon" <webmaster@xxxxxxxxxxxxxxxxxxxxx>]

hmmm...maybe some mil spec siesmic detectors cross-zoned with dual beam
pirs? whatever it will be it will be very expensive.


"Nomen Nescio" <nobody@xxxxxxxxx> wrote in message
news:1c355b1996fcf73a8860fba5bb2dc914@xxxxxxxxxxxx
| Stanley Barthfarkle said:
|
| >The key here is that you're trying to protect a narrow, curving strip of
| >perimeter area, and don't want any gaps. (in other words, spot protection
| >won't work) A reliable technology that provides proper catch performance
| >while eliminating false alarms in an outdoor area is going to be quite a
| >feat. If someone comes up with a viable, real world solution, and not
just
| >an idea on paper, I'd love to hear about how they did it.
|
| A buried cable system would work.  Two coax cables with intentionally
leaky
| shields establish a radio field between them.  A human body within this
| area affects the field, much like a radio's reception can be affected if
| you grab onto the antenna.  Warning:  this stuff isn't even remotely
cheap,
| and it requires trenching, obviously.  I would not consider this a DIY
| project.
|
| - badenov
|
|