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
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