Re: Radar Jamming

On Wed, 13 Apr 2005 21:05:25 +0800, Harvz wrote:

> Has anybody actually made a working radar jammer themself?

No, but I have thought about how you would make a spoofer.

You would have separate receive and transmit antennas. The receive antenna
would be fed to a mixer. The other mixer input would be a Doppler shift
frequency you generate according to vehicle speed (that is, it is the
exact amount of Doppler shift you need to send your detected speed down
to 0. Then you low pass filter the mixer output to select the lower
sideband, and send the output of the low pass filter to the transmit
antenna.

In reality, you probably couldn't design a low-pass filter with a sharp
enough cutoff, so you would have to get the lower sideband some other
way. The basic idea is to use a Single Side Band Suppressed Carrier type
of modulation. I'm not a microwave guru, so I would have to go read up on
this stuff a little more before I could say whether this would really work.

And it might be hard to provide sufficient isolation between the transmit
and receive antennas. The system might run off chasing its tail if the
transmit is allowed to feed back into the receive.

Anyway, it's easy to sketch a system out. The devil is in the details. ;-)

--Mac

.

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