Hi …….. and if you want to dig into ensembles of “non similar” clocks, you want to look into David Allan’s Smart Clock stuff….
http://www.allanstime.com/Publications/DWA/ <http://www.allanstime.com/Publications/DWA/> There’s also a lot of stuff there on clock ensembles in general. Bob > On Jun 16, 2019, at 7:22 AM, Poul-Henning Kamp <p...@phk.freebsd.dk> wrote: > > -------- > > >> Note that when you consider transitive measurement noise, you may find >> that making N simultaneous measurements against a single independent LO >> is simpler and better than making N(N-1)/2 measurements of all possible >> clock pairs. Think of star vs. ring vs. mesh networks. > > I think there is a fundamental assumption that needs to be stated clearly > here: > > 3-cornered hat and it's extensions are only productive with homogenous, > and preferably identical, sources. Ie: 3 identical OCXO's, 3 HP5071As. > > If you do a 3CH on a raw GPS-PPS, an Rb and a H-maser, you get a really > shitty result, because it attributes the worst properties of each source > to the "virtual source". > > For heterogenous sources, pretty much all proposed time-scale > algorithms degenerate to 1st or 2nd order PLLs with suitably chosen > parameters and filters. > > Arguably, the most important property of any timescale algorithm > is the ability to alert and exclude false-tickers as early as > possible, which makes Kalman filters obvious, despite their quirks. > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > p...@freebsd.org | 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@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
