Today, I did the check the settings for my BC637 card. I was surprised
that its overwrite my manual setting for the Leap Event by following
information:
Time Settings:
Mode : GPS
Time Format : Binary
Year : 1995
Local Offset : 0.0
Propagation Delay : 0
Current Leap Seconds : 16
Scheduled Leap Event Time : 876614400
Scheduled Leap Event Flag : Insertion
GPS Time Format : UTC Format
IEEE Daylight Savings Flag : Enable
"Sun, 12 Oct 1997 00:00:00 GMT". Its weird. I am going to re-insert it
and will check it again later.
New Time Settings are:
Mode : GPS
Time Format : Binary
Year : 2015
Local Offset : 0.0
Propagation Delay : 0
Current Leap Seconds : 16
Scheduled Leap Event Time : 1435708799
Scheduled Leap Event Flag : Insertion
GPS Time Format : UTC Format
IEEE Daylight Savings Flag : Enable
Also, my NTP, which rely on that card, didn't get the value for leap
second event yet:
# ntpq -c rv
associd=0 status=0028 leap_none, sync_unspec, 2 events, no_sys_peer,
version="ntpd 4.2.6p5@1.2349 Mon Sep 22 20:41:39 UTC 2014 (14)",
processor="x86_64", system="Linux/3.2.0-74-generic", leap=00, stratum=1,
precision=-23, rootdelay=0.000, rootdisp=8248.907, refid=BTFP,
reftime=d85e7526.957a1b17 Mon, Jan 12 2015 11:30:30.583,
clock=d85ec544.e1effe31 Mon, Jan 12 2015 17:12:20.882, peer=0, tc=4,
mintc=3, offset=3.757, frequency=-243.698, sys_jitter=0.000,
clk_jitter=1.328, clk_wander=15.616
Regards,
Vlad
It's fragile enough that there have been accidental false leap-second
events.
Yes, for example if there have been GPS receivers which decoded the
UTC parameters incorrectly, and started to announce a leap second when
there wasn't one (end of September).
That's why, for example, ntpd's leap second handling code has been
changed in v4.2.6 to accept a leap second warning only if the warning
is received from a majority of the configured servers.
If you want to be sure you can also provide ntpd with a leap second
file which is then (in current versions) considered as authentic
source for leap second information.
Martin
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--
WBW,
V.P.
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