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.