Hi,
I recently built an NTP reference clock using an Oncore VP on a
FreeBSD 5.4 system running ntp v4.2.0-a. ntptime shows an ever-
increasing "jitter exceeded" counter value which seems excessive (at
least to me). Was wondering if any of you had used the VP in this
role and if perhaps you saw the same behavior? Or should I even be
concerned?
I have the VP's pps line connected through a 2N2222 configured as an
inverter in front of a MAX232 in order to shift the TTL level into an
RS-232 level. The levels look fine on the 'scope when comparing the
pps line on one channel against the level-shifted line on the other.
Some screenshots follow..
Thanks in advance!
Jim
% ntptime
ntp_gettime() returns code 0 (OK)
time c6642065.3d34697c Wed, Jun 22 2005 13:37:41.239, (.239081709),
maximum error 3806 us, estimated error 3 us, TAI offset 0
ntp_adjtime() returns code 0 (OK)
modes 0x0 (),
offset 0.873 us, frequency 80.865 ppm, interval 256 s,
maximum error 3806 us, estimated error 3 us,
status 0x2107 (PLL,PPSFREQ,PPSTIME,PPSSIGNAL,NANO),
time constant 4, precision 0.001 us, tolerance 496 ppm,
pps frequency 80.865 ppm, stability 0.012 ppm, jitter 1.209 us,
intervals 800, jitter exceeded 2438, stability exceeded 0, errors 11.
% ntpdc -c kerninfo
pll offset: 1.106e-06 s
pll frequency: 80.865 ppm
maximum error: 0.006806 s
estimated error: 3e-06 s
status: 2107 pll ppsfreq ppstime ppssignal nano
pll time constant: 4
precision: 1e-09 s
frequency tolerance: 496 ppm
pps frequency: 80.865 ppm
pps stability: 0.012 ppm
pps jitter: 2.126e-06 s
calibration interval: 256 s
calibration cycles: 800
jitter exceeded: 2438
stability exceeded: 0
calibration errors: 11
% ntpq -p
remote refid st t when poll reach delay
offset jitter
========================================================================
======
*GPS_ONCORE(0) .GPS. 0 l 14 16 377 0.000
0.002 0.004
+time.nist.gov .ACTS. 1 u 24 64 377 34.147
-0.185 31.367
-ntp0.usno.navy. .USNO. 1 u 39 64 353 89.195
13.611 38.156
+navobs1.oar.net .USNO. 1 u 31 64 377 59.619
1.030 24.527
navobs1.gatech. .INIT. 16 u - 1024 0 0.000 0.000
4000.00
+timekeeper.isi. .GPS. 1 u 16 64 377 76.212
-1.565 49.556
224.0.1.1 .MCST. 16 u - 64 0 0.000 0.000
4000.00
%
_______________________________________________
time-nuts mailing list
[email protected]
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
