David, Jitter of .008 seems pretty good to me? That's better than my FreeBSD box gets with PPS. I realize that .000 would be preferable. ;-)
Regards, Ed > > Folks, > > I have been trying out the signed 64-bit serialpps.sys device driver > made available as a result of bug report 2108: > > https://support.ntp.org/bugs/show_bug.cgi?id=2108 > > http://support.ntp.org/people/burnicki/windows/serialpps-20120321- > signed.zip > > on a new 64-bit Windows-8 PC. However, I am not completely convinced > that the driver is working as intended, and wonder whether anyone else > has tried this driver? Without the driver, just using the DCD line > alone, NTP is working as expected, with an averaged jitter of about 9 > microseconds. Adding in the 64-bit serialpps.sys and ensuring that the > PPSAPI_DLLS environment variable was correctly set, the averaged jitter > was unchanged, but the drift (frequency offset) was about 1 ppm greater. > A new line appeared in the ntpq -p display: > > C:\Users\David>ntpq -p stamsund > remote refid st t when poll reach delay offset > jitter > ========================================================================== > ==== > oPPS(1) .PPS. 0 l 14 16 377 0.000 0.026 > 0.008 > *GPS_NMEA(1) .GPS. 0 l 13 16 377 0.000 -0.020 > 0.014 > +pixie .PPS. 1 u 20 32 377 0.311 0.046 > 0.023 > -Alta .PPS. 1 u 24 32 377 0.357 0.108 > 0.092 > +FEENIX .PPS. 1 u 7 32 377 0.310 0.049 > 0.426 > > with the "o" indicating that the kernel-mode was working correctly. > What I was expecting was that with the kernel-mode serialpps.sys, the > jitter would at least be different, and all being well the jitter would > be somewhat less than with user-mode time-stamping. That's what I've > seen on other systems. I see nothing in the Event Log which suggests > that NTP isn't working as expected, but neither am I seeing the expected > improvement. > > Here is an extract from my ntp.conf: > > # ATOM driver with serialpps.sys > server 127.127.22.1 minpoll 4 refid PPS flag3 1 > > # NMEA serial port driver - Garmin GPS 18x LVC > server 127.127.20.1 minpoll 4 mode 33 prefer > > I have tried flag3 as both 0 and 1, and there is no difference. > > It would be nice to mark this bug as VERIFIED, but with the results I > have I am reluctant to do so. > > (Perhaps I should count myself lucky that the motherboard actually still > has a COM port header!) > -- > Thanks, > David > Web: http://www.satsignal.eu > > _______________________________________________ > questions mailing list > [email protected] > http://lists.ntp.org/listinfo/questions _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
