From: Jim Richardson
Subject: Re: Radar basics?
Date: Sat, 19 Oct 2002 19:58:33 -0700
Organization: Erisian claw
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On Fri, 18 Oct 2002 19:59:22 GMT,
> On Tue, 15 Oct 2002 20:17:31 +0100, Terry Pinnell
>>I was interested to come across this radar-based alarm, which triggers
>>a 'dog barking' sound:
>>PIR would be an alternative, but this gadget above claims to work
> Took a look at the Webpage for product advertised. Isn't this just a
> simple motion detector?
> A radar implies a microwave generator, a means to channel the output
> to a target, a means to detect the refelction and process that into
> useful data. You aren't going to be able to do all that in the
> advertised package and certainly not for the price offered. The
> nearest equivalent is a Police radar gun. Maybe work from that model
> of equipment for your project.
There are plenty of CW style, and a few doppler, RADAR systems of that
size. The CW ones are small, relatively cheap, and easy to make if you
have a source for gunn diodes or other cheapo uwave generator. Most of
the ones I am familiar with are in the 10GHz band, they work
bistatically, (with a transmitter, and a reciever) as a sort of fence
line system, the mono static ones usually need to be able to turn of the
Tx or pulse it, and are more complex. But dual antennas and some
shielding to hid the Rx antenna from the Tx antenna works, although the
Sig/noise is obviously affected.
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