We had a presentation at our radio club several months ago on digital HF modes, and part of the presentation was on JT65 and apparently it needs a precise synchronized time fix on both ends for an exchange to occur. I do not recollect all of the details that were presented, but they did say that the default windows time keeper is not accurate enough, and advocated installing a third party ntp client that updates (way too) frequently.
-Brian On Wed, 2012-11-07 at 16:52 -0600, David wrote: > Some finicky software becomes upset if time is stepped backwards too > far. > > I have seen PC hardware clocks that drifted 30 seconds a day but that > only matters during a restart. The more common problem involves OS > time drift, often amounting to seconds per minute, caused by bad > System Management Mode code leading to lost interrupts or other > problems. A BIOS update or fiddling with the CPU power management > usually fixes that. > > On Wed, 7 Nov 2012 17:11:26 -0500, paul swed <paulsw...@gmail.com> > wrote: > > >Interesting I am unaware of any amateur service requiring that tight of > >a timing relationship. > >At least modern PC clocks do not drift that badly in a few minutes. So it > >is pretty odd. > >Without further detail I am at a loss for why you need to do that. > >Maybe he is tinkering with spreadspectrum? > >Regards > >Paul > > > >On Wed, Nov 7, 2012 at 5:04 PM, David <davidwh...@gmail.com> wrote: > > > >> Some Windows NTP clients like Tardis can calculate and implement a > >> clock frequency adjustment instead of stepping the clock if the time > >> adjustment is below a specified limit. If he was using an application > >> that was upset by the time being stepped, then that might allow less > >> frequent updates. > >> > >> If he is polling that often to maintain accurate time, then I would > >> assume he is using a local known to be accurate NTP server. > >> > >> There are Windows NTP clients which will synchronize to GPS PPS time. > >> That should be better than stock hardware and Windows can handle > >> anyway. Something like a Garmin GPS18 is specified to be within 1uS > >> and has a pulse to pulse jitter in the 10s of nanoseconds. > >> > >> On Wed, 7 Nov 2012 21:41:36 +0000, David Kirkby > >> <david.kir...@onetel.net> wrote: > >> > >> >Someone at my radio club uses some mode of operation where accurate > >> >time is required. He said the standard Windoze clock does not keep > >> >sufficiently accurate, so he has software which updates from an NTP > >> >server every 4 seconds or so. It's not exactly a denial of service > >> >(DOS) attack, but seems almost close to it in NTP terms to me. I can't > >> >really believe updating every few seconds is sensible myself, but he > >> >assures me it works very well. (I'm rather hoping it does not use a > >> >stratum 1 server!) > >> > > >> >I'm sure someone will say if you want accurate time on a PC, to use > >> >some combination of GPS, rubidium or OCXO with a 1 pps pulse and a > >> >serial port on a FreeBSD or similar computer. But that's probably not > >> >practical if your software only works on Windoze. > >> > > >> >Any comments? > >> > > >> >Dave, G8WRB. > >> > > >> >_______________________________________________ > >> >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. > > _______________________________________________ > 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.