From: Alan Horowitz <alanh@infi.net>
Date: Sun, 18 Aug 1996 08:58:57 +0800
To: "Timothy C. May" <tcmay@got.net>
Subject: Re: Stealth Buildings Was Re: "X-Ray Gun" for imperceptible searches
In-Reply-To: <ae3a68680e0210043016@[205.199.118.202]>
Message-ID: <Pine.SV4.3.91.960817185314.21584F-100000@larry.infi.net>
MIME-Version: 1.0
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YOu are correct that a gun cannot be imaged behind an actual screen.

I am correct that a peice of tinfoil doesn't comprise an actual screen.

Go price a shield room, and see how much is for materials, and how much 
is for labor.  Go talk to the crew that's putting it in; you'll see that 
they travel all the hell over the world putting these things in, because 
the vendor can't just hire some pick-up electricians and dry-wall types.

If the source radiates its EM waves, which reach and intercept the 
tinfoil, unless the tinfoil is correctly bonded, shielded, grounded, etc, 
the tinfile will re-radiate. That can be imaged.

I do this class of imaging, from signals that are weaker than these, for a
living. In fact, we sometimes have to apply attenuation at the front end
to stop overload of the amplifiers and signal processors.  No, I'm not 
going to talk about it. Not because I'm a hot-shit keeper of classified 
information, rather because I'm lazy, or maybe because I'm accustomed 
to getting paid for teaching? Most of the concepts are discussed in IEEE 
journals and other sources.  You could hand all the open sources, and a 
few billion dollars, to the Botswanians tomorrow; it would still take 
them a dozen years to get it working reliably. It's as much art as 
science. I guess the fancy word is "engineering".

You don't know how to do it; so what. I know how to troublehoot and 
repair it.