[ntp:questions] help - clock jumps up to 5000 ms startup ntpd with usb gps linux

David J Taylor david-taylor at blueyonder.co.uk.invalid
Sun Feb 19 17:10:16 UTC 2012


"unruh" <unruh at invalid.ca> wrote in message 
news:Zu90r.3511$zA2.2177 at newsfe02.iad...
> On 2012-02-19, Rob <nomail at example.com> wrote:
>> Ron Frazier (NTP) <timekeepingntplist at c3energy.com> wrote:
>>> *GPS_NMEA(5)     .GPS1.           0 l    4    8   37    0.000  563.733
>>
>> Don't try to use NMEA for timesyncing!  It will only drive you crazy.
>
> No. It is fine.

NMEA alone may be little better than Internet servers, it may be worse.

>> Some people are lucky and seem to be able to get a usable result, but
>> they really are working outside the specs and can get bitten at any
>> firmware change (as was recently seen with some Garmin firmware).
>
> Yes, you may have to recalibrate the offset after a firmware change. So?

The Garmin issue was more than a simple "recalibration required", but the 
released a fix.  "So" might be: "so use PPS as well as NMEA, both to 
improve performance dramatically and reduce or remove the need for 
recalibration.".

Cheers,
David 



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