From: Martin Spellman <mspellman@cix.compulink.co.uk>
Date: Sun, 3 Jul 94 10:04:16 PDT
To: mspellman@cix.compulink.co.uk
Subject: Van Eck Detection
Message-ID: <memo.546806@cix.compulink.co.uk>
MIME-Version: 1.0
Content-Type: text/plain



> > To: cypherpunks@toad.com
> > 
> > I've heard rumors through the years that CIA/NSA/whoever can aim a
> > parabolic antenna at your window, read the electronic pulses
> surrounding> your computer, and thusly determine what you are typing. 
> Is there any> truth to this?
 
> How far away, and whether a van parked a block away can do it, is
> unknown to me. There are people on this list who have done
> this...perhaps they can comment anonymously.
> 
> Note that the TEMPEST spec for shielding equipment is directly related
> to this.

In Britain we have 'TV detector Vans'. These are to detect licence 
evaders (you need to pay an annual licence for the BBC channels). They 
are provided by the Department of Trade and Industry. They use something 
like a small minibus and use Van Eck principles. They have two steerable 
detectors on the van roof so they can triangulate. But TV shops have to 
notify the Government of buyers - so that is the basic way in which 
licence evaders are detected.
I read of a case on a bulletin board where someone did not have a TV but 
used a PC. He got a knock on the door. They said he appeared to have a TV 
but they could not make out what channel he was watching!

Martin Spellman
<mspellman@cix.compulink.co.uk>