What is the "Bandwidth" of the "stuff" you are trying to measure?
You could set the analyzer to that or a little less, and then use relative
measurements.
You may need more gear if you are trying to measure a very low noise
wideband preamp.
Depends on what you are trying to measure.
Bigger bandwidth=higher noise floor, simply kTB. and it is a ratio if you
change kTB1/kTB2= B1/B2 (10 log it of course)

If you have the analyzer on, then connect the gizmo without signal and the
noise floor rises up 10 dB or more, you could probably ignore calculating
what the SA contributes. just add signal and it should be 6 dB or more above
noise floor established by your gizmo.

If not, then It is possible to calculate almost exactly the noise floor on
the analyzer to verify what is displayed is good, but you need a number or
two from the MFGR of the analyzer, which takes into account the filter shape
of the analyzer. (0.8 ot 1.6 something like that)

SAs are cool! What type do you have, makes a big difference, (depending on
what you are trying to measure) Some will not do it.


"Bill B." wrote in message
om...
Hello,
I need some help in figuring out how to properly use a Spec. Analyzer.
I have done several hours of research online now, and have somewhat of
an idea of what I am doing, but I just can't get down one piece of the
puzzle. In my line of work, we use simple devices that give us the
noise floor level in dB. I (stupidly) expected to be able to get this
same information easily out of a SA. As you may have guessed by now, I
ran into a problem when switching the RBW value. After much... much
reading, I fully understand *WHY* it changes (Filters increasing in
size cause a greater internal noise level, etc.) but I can't figure
the best way to get a "base" noise level reading. And as much as I
would like to fully understand the theory, what I really need is a few
more examples... IE: If you are looking a 100 MHz span and your RBW is
1MHz simply ___Fill in the Blank____ to find the base noise floor. To
further explain what I am trying to do, we are setting up a link that
requires a SNR of at least 6dB... I need to get the noise floor level
to compare with my projected signal strength for this link.

Please be nice... This is my first post grin

Thank you! Thank you!

Bill B. - N1SNI