The 85671A is fine, subject to the analyzer's LO noise floor. Some analyzers are quieter than others, but in no case can you use a spectrum analyzer by itself to characterize crystal oscillators or other high-quality HF sources.
I have a much nicer host-based application that does the same thing as the 85671A, runs on many different analyzers, and yields much more readable plots (see http://www.ke5fx.com/gpib/pn.htm ). There are also some pointers to app notes from Wenzel and HP on quadrature test sets in the last FAQ entry at http://www.ke5fx.com/gpib/faq.htm . The executive summary is that quadrature test sets are not that complex. You can save a lot of money by building your own, if you need to measure sources beyond the reach of your spectrum analyzer alone. That NIST box looks very nice but I have no idea what it does. If it's just a quadrature PLL and collection of filters, that can be done for a lot less than $4000. If it's got features like an ensemble of built-in reference oscillators, then $4000 could be a bargain. -- john, KE5FX > -----Original Message----- > From: [email protected] [mailto:[email protected]]on > Behalf Of J. L. Trantham > Sent: Monday, August 17, 2009 7:22 AM > To: 'Discussion of precise time and frequency measurement' > Subject: Re: [time-nuts] How do time-nuts measure phase noise? > > > Can anyone provide any information on the usefulness of the Phase Noise > Utility program (85671A) for the HP 8560 series Spectrum Analyzers? > > Thanks in advance, > > Joe > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Bruce Griffiths > Sent: Monday, August 17, 2009 7:13 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] How do time-nuts measure phase noise? > > > Some have commercial phase noise measurement systems like Symmetricoms > 5115A, 5120A. 5125A. Some have older HP phase noise measurement > systems like > the 3048A etc. The rest of us have to build our own systems based around > sound cards or surplus spectrum analysers together with the necessary > mixers, low noise amplifiers etc. > > Unless your sources are very noisy you wont be able to measure their phase > noise with just a selective voltmeter or even an RF spectrum analyser. If > you cant build it, then you need to acquire something like the > HP3048 or the > NIST phase noise measurement box currently on ebay.(Item: > 260423038423) > > Bruce > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
