From: tcmay@got.net (Timothy C. May)
Date: Sat, 17 Aug 1996 11:59:16 +0800
To: cypherpunks@toad.com
Subject: Re: Stealth Buildings Was Re: "X-Ray Gun" for imperceptible searches
Message-ID: <ae3a68680e0210043016@[205.199.118.202]>
MIME-Version: 1.0
Content-Type: text/plain


At 8:58 PM 8/16/96, Alan Horowitz wrote:
>TIm, a layer of tin foil is not the same as a professionally installed
>and maintained Faraday cage.
>
>I can envision circulating currents on the tinfoil. Ie, ground loop type
>of situation.
>
>All imaging is depenmdant upon the target having some radiating
>characteristic. If the gun shields a gun-shaped peice of the body from
>radiating in millimeter waves, you can build a gun detector.

There's no other way to say this: you simply don't know what you're talking
about. Your protestations to the contrary, reconstruction of an image from
point sources of leakage is essentially impossible ("the phase problem").

Analyze the solutions for sources behind screens. (A simple model is to
analyze the radiation patterns one one side of conducting plate, with
various sources on the other side.)

For an intuitively visualizable model, consider a pattern of some sort
(like a gun) behind a screen, with light leaking around the edges. (The
less light leaks, the more the example is similar to the case of deliberate
shielding of RF sources, but even the simple example here makes the point.)

This is what crystallographers and DNA analysts call "the phase problem."
Spatial frequency (pattern) information is indeterminate.

If you still believe what you say, that a gun can be imaged even when
behind a conducting screen, based solely on leakage around the edges (or
similar small leaks), I challenge you to produce a paper which demonstrates
this, or, even better, an actual demonstration.

--Tim May

Boycott "Big Brother Inside" software!
We got computers, we're tapping phone lines, we know that that ain't allowed.
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