Re: SOFT TEMPEST (fwd)

[Dave Emery <die@die.com>]

On Tue, Feb 10, 1998 at 03:03:53AM +0100, Lucky Green wrote:
> 
> Now all this was done without the use of a DSP. I can only imagine what
> one could capture after adding a DSP to the setup.

	Miles...
	
	Given static screen images and thousands of repetitions in a few
seconds the processing gain from integration of the signal verus the 
uncorrelated noise over thousands of cycles gets quite interesting. And
add to that the tricks one can do with comb filters and combining
together the correllated energy from several harmonics of the dot clock
one can see that getting signal out from under the trash is easy even at
considerable distances.   It has, in fact, been speculated that the
larger NSA geo and near geosync ELINT/COMINT satellites probably have
the required capability to accomplish this from orbit (with football
field sized antennas this isn't out of the question at all).

	Also the "frequency generator" you talk about needs not be
some extremely expensive HP synthesizer (often of course available for
a few dollars at the local ham radio flea markets in any case), but
simply a good voltage controlled crystal oscillator on the right frequency.
These are $5 parts...
	
-- 
	Dave Emery N1PRE,  die@die.com  DIE Consulting, Weston, Mass. 
PGP fingerprint = 2047/4D7B08D1 DE 6E E1 CC 1F 1D 96 E2  5D 27 BD B0 24 88 C3 18