The frequency accuracy is related to the conversion process, the sampling process and the computation that follows. In a sampling VNA the frequency is extracted after the FFT, I suppose, so I don't think that sampling VNAs can do any better than a real frequency counter. Sweeping spectrum analyzers seems to stop for some time the sweep at the marker and route the IF to a real counter, when the counter is called in: this should be more accurate.
On Wed, Nov 14, 2012 at 3:30 AM, Bob Camp <li...@rtty.us> wrote: > Hi > > The help file is correct, but possibly a bit misleading. Most of what they > show could be done by a computing counter. They have been around long > enough that they are a sub $100 ($50?) item these days. Clock jitter is > going to be a very real limit doing what they are trying to do. > > Bpb > > On Nov 13, 2012, at 8:27 PM, Malcolm <g0...@aol.com> wrote: > > > I have been looking at the DG8SAQ VNA for other purposes and it is > suggested in the VNWA_Help.pdf on page 158 that it can be used as a high > accuracy / resolution counter. Document available at > http://www.sdr-kits.net/vnwasoftware/?20 . > > > > Ignoring any drift in the TXCO as I would drive it from an external > reference source ( GPSDO or Rb derived) of 36 MHz, being a (junior in > knowledge) time nut I added this as another reason to buy the VNA. > However, I do have some reservations and would like the comments of better > qualified time nuts and the answers to some questions:- > > > > 1. Can the VNA really have that level of resolution? > > > > 2. Is the resolution reduced in the ratio of the measured frequency > to the clock frequency e.g. at 360 MHz is the resolution 10 times worse > than that at 36 MHz? > > > > 3. Are there any other factors that should be taken into account when > performing frequency measurement please? > > > > Whether or not this feature works is not a deciding factor in my > consideration just a possible plus. > > > > Your comments please ladies and gentlemen. > > > > Regards > > > > Malcolm > > G0MIC > > _______________________________________________ > > 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. > > > _______________________________________________ > 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. > _______________________________________________ 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.
