[Premium-Rx] Modern stuff vs. vintage WJ

[Jeff Kruth]

Hi Brooke!
 
 As a matter of fact.........Thats why the 8560X series of HP spec ans have a 21.4 MHz final IF mixed down from 321.4MHz: They were responding to gov't requests to provide that output so that the mountains of existing demod/analysis gear could be used with the spec ans as tunable MW front ends. Pricey way of doing things, nice to have deep pockets.____________

There is an ad in the JED from SRL for a receiver system, from the mid '80's, showing 14 HP 8566A's in a three bay rack system, with a pile of other "stuff", including WJ demod boxes, at a time when an 8566A was $65K.  900K in "front ends, but very good probability-of-intercept, and, of course, nice '488 control._______________
Tempest had very specific standards in certain critical response areas such as filters, pulse recovery times, etc. Much of the work is similar to EMI, but not the same.____________
Some of the Tempest work was snooping against uncooperative targets, so distance, antennas, pre-amps etc were required. Was not all "done in a lab". I have witnessed these tests from the inside of a innocuous looking big white panel truck, Joes Landscaping or somesuch on the side. Sides of the box were fiberglass, antennas inside the box looking out. Park along the road by a contractor and see what leaks out of the "secure" installation.______________
 
I am only saying I have a special place in my heart for the WJ stuff. It was the Cadillac of surveillance gear in its day.  As with all things, something else comes along.... 
______________I do not collect the mini-nano-pico cepter stuff. My love is in the knobs/dials/ switch era of the black paneled spook gear._____________
 
I know if I had to do a job for a serious customer now where the max in performance was needed and I had the bucks, I would use a different tech base these days._____________
 
Then there is the non-Tempest signals intercept work where multilayered modulation needed very flexible equipment, but small quantities of it, so no HP or Tek project manager was interested in building something they would only ever sell 100 pieces of.  Companies like WJ & ACL thrived on that business model. Specials were their specialty!____________
Like I say, fun stuff, but if serious, use an modern RTSA with all the bells and whistles.________ Tek has some nice ones!_____________ I replied to the group as I thought there was some general interest stuff here!----------
 
Regards, Jeff----------------------
 
In a message dated 5/31/2018 7:32:02 PM Eastern Standard Time, brooke at pacific.net writes:
 
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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