[Premium-Rx] (no subject)

[Jeff Kruth]

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__________