how important is the close in phase noise of a 10MHz reference? I means after all, the oscillator you are measuring, say the local oscillator in a receivers or whatever, is likely not running at 10MHz so you have some step where you convert your t-bolt reference to the desired freq. using either DDS or a synthesizer and I'd bet that step introduces more noise and is the weak link.
I did mean this as a question because I really don't know how to compute the effect. Say my DDS needs 120MHz clock and I PLL that 120Mhz clock to my t-bolt and then the DDS as asked to outout 14.5MHz. How do phase noise in the 10MHz t-bolt output effect the DDS' 14.5 output. Or does it even matter compared to all the noise from other sources. Is there a simple rule of thumb? OK, maybe we are not really doing any real-measurements, just comparing 10MHz standards to each other? But the above assumes the end goal is some real-world device who performance we want to determine. On Fri, Sep 28, 2012 at 11:50 AM, Murray Greenman <denw...@orcon.net.nz> wrote: > Ulrich, > I think this is a bit like discussing one's favourite wine or favourite > stereo! Especially since many of the participants here will not have the > capability to compare GPSDO performance reliably. > > I have a few GPSDOs, and it's my impression that of them all the Agilent > Z3815A with MTI260 DOCXO has the best phase noise. Of course these units > were originally equipped with an E1938A, and the later MTI260 version is not > as common. > > I also have an E1938A, which I operate standalone. It is very impressive, > excellent AD, in fact my best source now that I've given away my HP 5065A. > There is some phase noise well away from the carrier, but I've put that down > to my own construction (switching power supply noise). > > Another of my favourites with low phase noise is the Trimble/Nortel > NTGS50AA, which has a CMAC/Rakon CFPO-DO OCXO. I've had no opportunity to > measure the AD apart from what Lady Heather reports. This unit is physically > large but is not power hungry and talks to LH very well. > > I also own a Z3801A, a Samsung GCRU-D and a small homebrew GPSDO with a > CFPO-DO. Sorry, no Timepod for comparisons. > > 73, > Murray ZL1BPU > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
