Poul, > The field in the oncores serial data-stream called negative > sawtooth correction must be taken into account to get optimum > performance out of the receiver. Ignoring it in toto or > simply averaging it will generally not do for OCXO disciplining.
thank you for your clear words! While my posting has produced a lot of different points to discuss over, this is basically what I had expected from a experienced person. I hope you needn't cross your fingers while writing it down! Best regards Ulrich Bangert, DF6JB > -----Ursprüngliche Nachricht----- > Von: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Im Auftrag von Poul-Henning Kamp > Gesendet: Dienstag, 26. Dezember 2006 03:02 > An: Discussion of precise time and frequency measurement > Betreff: Re: [time-nuts] TIC resolution impact on GPSDO's performance > > > In message <[EMAIL PROTECTED]>, Dr Bruce Griffiths writes: > > >Poul-Henning > > > >You are using a different meaning for coherence than the > standard one. > >The standard meaning is something like: Two signals or waves > are said > >to be */coherent/ *if their behaviour at various > times/places is linked > >in a deterministic way. > > The term coherence originates in optics and was briefly used > in radiotelegraphy and is no almost exclusively used in the > context of lasers and waveguides. > > When two signals are coherent, you can predict one from the other. > > We are dealing with three signals here: > > GPS_PPS: the 1 Hz signal as the Oncore wants to do it. > > HW_PPS: the 1 Hz signal as the Oncore can do it. > > NEG_SAW: (GPS_PPS - HW_PPS) > > None of the above three signals are coherent, you need two > out of three to predict the last one. > > And since the first one is a virtual signal, not available > except as the sum of the other two, talking about coherence > is especially pointless. > > I think what you are trying to express is that the frequency > from the internal Xtal (at times) is in an overtone of the > 1Hz PPS, which gives rise to hanging bridges. > > And to conclude this by now surely far too tiresome debate > before both of us gets booted from the list: > > The field in the oncores serial data-stream called negative > sawtooth correction must be taken into account to get optimum > performance out of the receiver. Ignoring it in toto or > simply averaging it will generally not do for OCXO disciplining. > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > [EMAIL PROTECTED] | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by > incompetence. > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts > _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
