Hello. I work in a physics research lab, and we are planning to purchase a spectrum analyzer. We need to cover the range from DC (actually, 0.1 Hz would be enough) to 300-400 kHz to look at the electronic error signals we get in a laser stabilization experiment (these are just the electronic representation of frequency fluctuations of the laser, most of them due to mechanical vibrations in this range of frequencies). This is the "essential minimum" we need, but since we are making the investment it'd also be nice to be able to go to higher frequencies, we'd have plenty of additional uses for an instrument reaching up to 100 MHz. Ideally the instrument would be of the FFT flavor.
We have been looking at a number of models and there aren't many which cover the low frequencies down to tenths of a Hertz, this seems to be the main limitation. The 89400 series of Agilent seems to be all we need and more, but it costs a kidney, so one option we are considering is to sacrifice a little bit of range in the low frequencies and go with a 4395A (from 10 Hz) or even better, a 4396B (from 2 Hz). These models are more affordable and have the added advantage of incorporating network and impedance analyzer funcionality, which is not essential in our case but certainly nice to have in a lab like ours, we have to build and test plenty of home-made circuits and little gizmos.
The second possibility we are considering is a PC-based solution like the
89600 series, we would only need to purchase a suitable laptop, the software (the 89640 seems adequate) and a hardware front-end like a VXI mainframe. The final price is probably quite a bit lower than that of a standalone instrument.What I would like is to get some opinions of people who have working experience with these two types of spectrum analyzer, standalone and software-based. Which one would you recommend for lab use? What are the advantages and disadvantages of each one? In terms of functionality, is any of the options clearly superior to the other one? I have only mentioned HP (Agilent) products, but please feel free to recommend any other brands/models that you consider adequate for this task.
Thanks a lot!