[ntp:questions] UTC Time from NMEA receiver one second behind DCF?

Hal Murray hal-usenet at ip-64-139-1-69.sjc.megapath.net
Tue Aug 12 20:22:28 UTC 2008

>I am using a Navilock NL-320U connected to a small Linux box running ntp
>4.2.4p4-44.1 that came with the openSuSE 11.0 distribution. This is
>supposed to supply a time service to the local network without the use of
>external network ntp servers purely from the received GPS signal.
>I know that using a USB connection is not optimal, but the achieved accuracy
>is fine for my needs.

>Last Saturday (2008-08-02) I noticed for the first time that the time off
>the GPS unit was one second behind the DCF time, which I monitor on a
>separate radio clock. A reboot of the system did not help. On Sunday
>(2008-08-03) everything was back to normal. I noticed the same effect again
>on Friday evening (2008-08-08) and through yesterday (2008-08-09), but
>everything seems fine today (2008-08-10).

[big snip]

>My question is, has anyone else observed this and how can I fix this?

I've seen similar quirks from GPS units using the SiRF chip set.

It started about the time the leap second was announced.  (Otherwise,
they work, but not very well.  They have a 100 ms jitter/drift.)

It looks like a weekly pattern.  It will be interesting to see what happens
during the next week.

These are my opinions, not necessarily my employer's.  I hate spam.

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