[time-nuts] A question about GPS pps quality.
John Ackermann N8UR
jra at febo.com
Thu Jul 26 17:05:13 UTC 2007
Poul-Henning Kamp said the following on 07/26/2007 11:46 AM:
> In message <46A8C00D.50603 at kudra.com>, Robert Sexton writes:
>> ); SAEximRunCond expanded to false
>
>> 1. If I interface one of these to my closet-based server, do I really
>> have a Stratum-1 source? 1us accuracy doesn't sound all that great, but
>> I'm nut so sure that the server can take advantage of a pulse with
>> greater accuracy.
>
> Stratum-1 - certainly. 1us accuracy ? Highly unlikely.
>
> The clock crystal in your computer is far too temperature sensitive
> for that.
>
>> 2. Would I get significantly better performance if I shelled out $75
>> for one of the new trimble timing GPS modules, or found an old oncore
>> timing module on ebay?
>
> No.
>
>> I know that the oscillator on my old AMD based UNIX machine isn't all
>> that great, but I'll leave that question for another time.
>
> That is where you should spend your money first.
>
> Any GPS with a PPS output is sufficient to what you can do with a
> normal clock crystal.
Poul-Henning speaks with more practical NTP experience than I do, so I'd
give greater weight to his answer than to mine...
John
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