[ntp:questions] Re: Bought a GPS receiver--What next?

Terje Mathisen terje.mathisen at hda.hydro.com
Tue Nov 2 13:58:37 UTC 2004


John R. Ackermann N8UR wrote:
> But the short story is that over 12 hours, and after removing the Rb's 
> frequency offset (about -1.5x10e-12), the "noise" on the 1pps output 
> from the GPS is +/-60ns, with a small number of peaks that extend a few 
> nanoseconds further -- the absolute maximum deviation over the period 
> was about +/-75ns, with only a couple of samples hitting that extreme. 
> Averaging over 100 seconds reduces the noise to the +/-15ns range.  Oh, 
> and I'm not using the sawtooth correction capability of the M12T -- I'm 
> just looking at the raw PPS output.

Given that the sawtooth error is at least +/- 50 ns, your +/- 60 ns 
results would seem to be _very_ good. :-)
> 
> I'll try again tonight to generate a plot and will post the URL here.

Good!

Terje
la8nw
-- 
- <Terje.Mathisen at hda.hydro.com>
"almost all programming can be viewed as an exercise in caching"



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