[ntp:questions] NTP server with Garmin GPS 18 LVC

unruh unruh at invalid.ca
Thu Dec 19 19:25:30 UTC 2013

On 2013-12-19, David Lord <snews at lordynet.org> wrote:
> Adrian P wrote:
> .....
>> Everywhere is written that FreeBSD is the best OS for time keeper,
>> since its kernel supports nanosecond accuracies. However, if GPS 18x
>> LVC PPS signal has only microsecond accuracy, then I suppose there is
>> no point on using FreeBSD, any linux would be okay as well. So what do
>> you think, looking from NTP point of view only, is this nanosecond
>> accuracy the only reason why someone would use FreeBSD, or there are
>> some other reasons as well? I see you have experience with all kind of
>> OSes.
> I think the combination of hardware used is at least as important
> as the OS.
><http://www.febo.com/pages/soekris/> 100ns accuracy

AGreed. But their comparison is strongly cooked. At least on my system,
the serial port interrupt performace is far better than theirs--
something like 2 us, not the 50us they are showing. Certainly 100ns is
better, but more like one order of magnitude, not more than 2. 

><http://www.synclab.org/radclock/> An alternative to ntpd
> David

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