From: jim bell <jimbell@pacifier.com>
Date: Thu, 30 May 1996 05:37:27 +0800
To: SINCLAIR  DOUGLAS N <proff@suburbia.net (Julian Assange)
Subject: Re: Tempest Info
Message-ID: <199605291556.IAA21231@mail.pacifier.com>
MIME-Version: 1.0
Content-Type: text/plain


At 09:27 AM 5/29/96 -0400, SINCLAIR  DOUGLAS N wrote:
>> Water pipes are often form the earth line. If only 60hz (US) can get through
>> the power cables then only 60 hz can get into the water pipes (I'll ignore
>> re-radiating, because water pipes are the least of your problems there).
>
>The high-frequency harmonics from your computers are probably above the
>cutoff frequency of the water-pipes when considered as circular waveguides.
>The water filling will act as a dielectric, bringing F0 down.  So, it
>is conceivable that extremely high frequency radiation (>3 Ghz) could
>propagate well in a water pipe.

No, you misunderstood.  The RF wouldn't be transmitted on the inside of the 
pipes (how could it get inside, anyway?) but on the outside.  Since most 
information-containing appliances are well-grounded, there is at least a 
strong possibility that a ground connection would carry enough interesting 
RF to be useful to tap.

Jim Bell
jimbell@pacifier.com