[Premium-Rx] (no subject)

[Brooke Clarke]

Hi Jeff:

I think the Tempest receivers are trying to find RF signals signals as either conducted or radiated from equipment under 
test.  In Tempest testing you're not trying to demodulate the signals, although that's part of an attack using Tempest 
methods.  The HP 4395 and 70,000 series spectrum analyzers are orders of magnitude better at this than the CEI 
receivers.  For me getting a 70,000 system or another DSP based spectrum analyzer system working would be much more 
interesting.  The 4395 has no provision for an external demodulator, but the HP 70,000 system has plenty of options in 
that area.
http://www.prc68.com/I/4395A.shtml#SA
http://www.prc68.com/I/HP71100C.html

There are VXI spectrum analyzers that are the basis of some very sophisticated systems.

-- 
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

-------- Original Message --------
> Hi: I have a bunch of CEI Tempest receivers that I combined into a rack, BUT . . . they are pretty much deaf compared to more modern equipment.  Because of kTBR noise the ultimate sensitivity depends on how narrow the real bandwidth of the receiver is, so something like the HP 4395A in Spectrum analyzer mode with a true RBW of 1 Hz  .......
>
>   
> _________To answer this: N=kTB depends not only on bandwidth (which traditionally is driven by modulation or data rate) but T which is T-system which is the noise figure (and some other factors) of the system. A spectrum analyzer is a great tool, but in the past was a poor receiver up to 1 Ghz or so, due to lack of preselection below 1 Ghz (which, in a dense signal envirorment would lead to a lot of spurious responses due to intermod) and the usually quite high noise figure (20 dB).__________
>   
> The old CEI receivers had noise figure well under 10 dB, more like 3-5, so they were quite sensitive. Very nice multistage preselection. Only the WJ 9080 was not preselected AFAIK.  Perhaps yours have tired front ends?____________
>   
> No question a modern FFT based analyzer can see very small amounts of energy in a 1 Hz bandwidth. But how much better is it in a 20 KHz bin size? ___________
>   
> YMMV_Jeff__________
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