[time-nuts] GPS jump
michael.cook at sfr.fr
Fri Oct 10 01:06:13 EDT 2014
Le 10 oct. 2014 à 03:09, Bob Camp a écrit :
> GPS is steered by the Air Force last time I checked.
> A really good place to check is the NIST Time and Frequency pages that show both real time and historical data for each GPS sat compared to NIST time:
> Hopefully it’s accessible via that link from a variety of locations.
> Since the NIST data is independent of the steering (two different outfits involved) it should not be vulnerable to a “our ground segment broke and we steered everything to match” sort of error.
> On Oct 9, 2014, at 7:43 PM, Jim Palfreyman <jim77742 at gmail.com> wrote:
>> We look after 5 separate hydrogen masers spread all over Australia and we
>> collect tic phases between the masers and the GPS.
>> On around ~Oct 7 we have noticed that the normal steady straight line (with
>> standard daily noise) took a noticeable downward turn - on all 5 masers.
I remember Jim reported a similar issue back in october last year:
>> On 2013-10-03 05:33, Jim Palfreyman wrote:
>>> Noticed an above average bump in our H-Maser vs GPS graphs - from sites
>>> over Australia.
>>> Recent coronal mass ejection or US government shutdown not updating GPS?
>>> Anyone else seen it?
>> drop out gap between about 04.21-04.26 UTC?
>> 56568 15684.876 127.127.20.4 $GPRMC 042124 A ...
>> 56568 16004.862 127.127.20.4 $GPRMC 042644 A ...
>> 56568 15684.876 127.127.20.4 961a -0.000002270 ... 0.000005344
>> 56568 16004.862 127.127.20.4 961a -0.000013150 ... 0.000015721
>> 56568 15684.876 -0.000002270 0.899 0.000007071 0.000070 4
>> 56568 16004.862 -0.000013150 0.898 0.000008830 0.000114 4
That dates are close enough to make you wonder if it is not part of some cycle.
>> Did anyone else who tracks H-masers notice this as well?
>> Is it JPL making corrections?
>> Jim Palfreyman
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