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

Harald Brinkmann hb7267 at gmx.de
Mon Aug 11 20:06:43 UTC 2008


Unruh wrote:

> Harald Brinkmann <hb7267 at gmx.de> writes:
> 
>>Richard B. Gilbert wrote:
> 
>>> It sounds as if the GPS receiver you have was designed for navigation
>>> rather than timing!
>>> 
>>> Timing receivers typically have a Pulse Per Second (PPS) output and use
>>> a binary protocol rather than NMEA to transmit the time to a serial
>>> port.
>>> 
>>> Using the proper tool for the job should solve many of your problems.
> 
>> Point taken. Didn't I mention I am a cheapskate? ;-)
> 
> The Garmin 18LVC reveiver is about $60, and has a pps and serial output--
> some wiring is required.

The only European source for the Garmin 18LVC I found asks for 160 Euro.
 
> It is not clear what is happening. what GPS receiver is it? What are you
> running to get the time off of it?

>>> Harald Brinkmann wrote:
>>>> This is my setup:
>>>> 
>>>> I am using a Navilock NL-302U connected to a small Linux box running
>>>> ntp 4.2.4p4-44.1 that came with the openSuSE 11.0 distribution.
(Please note the corrected transposed digits in the receiver type.)

I think the point I am interested in is still not yet quite clear to those
to have been kind enough to reply. I have had this setup up and running for
about 18 months. The achieved accuracy has always been better than 100
milliseconds, which may sound awful to most of you, but is good enough for
my needs. Now, all of a sudden, and only on some days, do I get an offset
of more or less exactly one second. I haven't yet observed any offsets of
less than one second. I also haven't observed any bigger offsets. It is
always either this one second offset or normal operation with relatively
small offsets that I don't worry about. All of this only began to happen in
the last week or so. Apparently the Navilock uses the Sirf III chipset,
which seems to be in widespread use. If there is a bug in there, it should
have happened to someone else as well, right?




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