[ntp:questions] best gps receiver for time synchronization

Unruh unruh-spam at physics.ubc.ca
Tue May 12 20:36:33 UTC 2009


"David J Taylor" <david-taylor at blueyonder.not-this-part.nor-this.co.uk.invalid> writes:

>Unruh wrote:
>> "David J Taylor"
>[]
>>> On my system, I can detect no difference between the GPS 18 and the
>>> GSP 18x.  I am looking at jitters in the order of 2.2 microseconds,
>>> and offsets in the range +170/-100 microseconds.
>>
>> How are you reading the PPS interrupts>. That offset is terrible. On
>> my PPS feeding a parallel interrups, the offsets are less than 10us.

>This is a Windows system, Bill.  I know I would do far better with a 
>FreeBSD system (I used to get better than 20microsecond offsets), but I'm 
>able to run one PC less now, by having a Windows PC as my stratum-1 
>server.

OK, I keep forgetting. What accuracy can the clock be read on windows?
is there an interpolation routine in the kernel so the clock can be read
to usec accuracy?
I would thin k you could set up and interrupt routine to read and record
the clock time when the interrupt occurs.


>The offset is more than good enough for my purposes.

>Cheers,
>David




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