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Re: Tempest Info
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
[email protected]