Hi Doesn't everybody run OCXO's for the clock in their PC?
Bob On Nov 25, 2009, at 4:41 PM, Lux, Jim (337C) wrote: >> You aren't going to get nanosecond accuracy out of a ntp server running over >> an ethernet[1]. On the other hand, sub-ms isn't hard with a good OS and/or >> good software. >> >> It's fairly easy to get a reasonable sanity check on a (s)ntp server. Just >> setup a known good ntp system and have it monitor the DUT. The reference >> implementation for ntp (http://www.ntp.org/) has lots of support for >> collecting data. >> >> The key step in making a PC keep good time is tweaking the clock frequency. >> This is the software equivalent of the EFC on an oscillator. ntpd calls it >> drift. You can use it as a thermometer. > > I don't think the oscillator quality in the typical PC is good enough to ever > get nanoseconds, even with tons of tweaks and temperature compensation, etc. > The short term variability/phase noise is too high. > > Microseconds, I think you could do. > > > > >> >> ---------- >> >> 1) There is a group working on that level of accuracy. It takes special >> hardware that can put a time-stamp on a packet as it leaves or arrives. >> http://en.wikipedia.org/wiki/Precision_Time_Protocol >> >> > > More than just a casual group. You can buy IEEE 1588 products from, among > others, Symmetricom. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
