Re: SOFT TEMPEST (fwd)

[Jim Choate <ravage@ssz.com>]

Forwarded message:

> Date: Tue, 10 Feb 1998 06:46:55 +0100 (CET)
> From: Lucky Green <shamrock@cypherpunks.to>
> Subject: Re: SOFT TEMPEST (fwd)

> That would be my analysis as well. Note that the van Eck demonstration I
> saw didn't even make use of the common analog tricks, such as using a
> super heterodyne receiver.

In what context? The only place a super-het would buy you any selectivity,
and its tight bandwidth may actualy work against you, is in capturing the
data on each trace. The syn pulses aren't amplitude sensitive so much as
time ordered. If you can get a clear signal use that to fire a Schmitt
trigger and synthesize your sync pulses and ramps/stairstep generators from
that. Using a super-het for this is over-kill.

> Not to mention the near magical capabilities of
> a few Fourier transforms for pulling a nice, fat signal spike out of all
> that "white noise".

Doing a Fourier on the grass won't pull the signal out unless you've got an
integration function in there to filter the noise (ala flying cap filter).
If the signal is strong enough that a Fourier can be applied to it then the
signal is most likely strong enough to use directly. The data we're trying
to get out isn't that complicated; two sync pulses and the e-beam modulation
data.

I would like to request that you provide a better description of the
equipment used at HIP for the demo. If the various descriptions of that are
accurate his signal detection range was around 50 - 100 ft. and he was using
specialy sized fonts (special in the context that you wouldn't use them for
a spreadsheet or document processing). Is this correct?


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