Re: SOFT TEMPEST (fwd)

[Lucky Green <shamrock@cypherpunks.to>]

On Mon, 9 Feb 1998, Dave Emery wrote:

> 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.

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. 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".

There wasn't a single person watching said demonstration in that brutally
hot tent at HIP'97 that didn't walk away impressed. And I can off the top
of my head come up with a design that would improve the gain by at least
20dB over what was used there..


-- Lucky Green <shamrock@cypherpunks.to> PGP v5 encrypted email preferred.
   "Tonga? Where the hell is Tonga? They have Cypherpunks there?"