Remember, the narrower the bandwidth on something the more sensitivty it can get. Theoretical sensitivty is -174dB, problem is that is at 1Hz of bandwidth.
I would recommend slowing the sweep rate, narrowing the IF filter and taking smaller sweeps at a time. a 100kHz sweep with 10kHz per division is alot 'cleaner' then a 1MHz sweep. You can even try a 1kHz per division sweep. Then I would add them using a graphic editing program or simply cut the individual pieces of paper together from a printer. Connect the SA to a 50 ohm dummy load and experiment until you get a setting that works for you. I understand Rhode and Schwartz makes a great spectrum analyzer that has some insane noise floor, but is $80,000. On 4/24/07, vintageaudio2004 <[EMAIL PROTECTED]> wrote: > I have a quick question for the group about the noise floor of a > spectrum analyzer, hope that with the collective knowledge and > experience somebody can help me out a bit. > > We have customer that needed a couple of site surveys done, in order > to detect any possible interference sources on 3 segments of 2MHz each > (we used the 200KHz/div screen span setting), in the 455-465MHz > region. Surveys have already been completed, but the customer is now > asking us to redo a few of the site surveys that didn't catch any > interference because the noise baseline on the instrument that was > used is -110dbm. The customer says he needs it done at a noise floor > of -124dbm to make sure the frequencies are really clean. > > Could anybody clarify how one does lower the noise floor of the > analyzer? It was my understanding that the noise floor is a intrinsic > characteristic of the instrument itself, and is so to say a > measurement limit that cannot be varied without external aids (or > maybe with a low-noise LNA?). But if one uses an external amplifier, > wouldn't this also raise the site noise floor on the analyzer screen? > Or if I am wrong, how could one lower the noise floor of the > measurement in order to be able to take measurements at lower levels? > Or is the noise floor also a function of the SITE noise level per se? > > BTW, we used a IFR (Aeroflex) COM-120B during the surveys, coupled > with the EasySpan II software to make the screen captures. > > Thanks. > -Alex
