[ntp:questions] ESR looking for good GPS clocks
David J Taylor
david-taylor at blueyonder.co.uk.invalid
Wed Mar 7 08:35:52 UTC 2012
"Ron Frazier (NTP)" <timekeepingntplist at c3energy.com> wrote in message
news:4F566EBD.2020703 at c3energy.com...
> On 3/6/2012 11:00 AM, David J Taylor wrote:
[]
>> http://www.satsignal.eu/ntp/Garmin-GSP18x-LVC-firmware-issue.htm
>> http://www.satsignal.eu/ntp/Garmin-18x-3.7.png
[]
> I looked at that chart 3 times and even zoomed in on it. It looks like
> to me that the vertical scale is in ns. So, the variation in start time
> for the NMEA sentence is about 170 ns if I'm reading it right, not ms.
> In that case, it's about 2/10 of a us. This would have little impact
> compared to the 170 ms of possible variation we're discussing.
It's milliseconds.
>> The table here:
>>
>> http://www.satsignal.eu/ntp/Garmin-18x-3.7.png
>>
>> lists two SiRF devices with a claimed 1 us accuracy. PPS, not NMEA.
> I think that may be the wrong link. I can't find any devices listed
> there.
Indeed! <G> Please see:
http://gpsd.berlios.de/hardware.html#timing
Cheers,
David
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