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

John Ackermann N8UR jra at febo.com
Wed Nov 3 02:29:04 UTC 2004


Terje Mathisen wrote:
> 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.

As threatened, I've put performance plots of an M12+ Timing Oncore 
versus an Rb standard at 
http://www.febo.com/time-freq/gps/performance/index.html.

Enjoy.

John



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