[time-nuts] GPS Sat Clock Data
bg at lysator.liu.se
bg at lysator.liu.se
Fri Jun 4 05:10:29 UTC 2010
I have in the past watched presentations at ION on "signal in space" (SIS)
accuracy for the GPS constellation. There was a steady improvement, with
leaps between different SV (clock) generations. But also an improvements
with adjustments in the ground segment, including adding more ground
monitor sites. I am pretty sure there was also AVAR(?) plots for
individual SVs maybe only clock types. One of the presentations was from
Lookheed Martin where the new data was from II-RMs.
> That's pretty close to what I'm looking for. The ideal would be to have
> variance vs a range of tau for each individual sat. If there's a way to
> get that from the NIST site, I've overlooked it. The "whole constellation"
> data vs a range of tau is a reasonable starting point. The thing I was
> surprised by was the range of performance of each sat as shown in the
> paper I mentioned.
> On Jun 3, 2010, at 9:54 PM, Brian Kirby wrote:
>> I do not know if this is what your looking for,
>> follow the directions on the date....
>> You can look at individual SVN performance, etc.
>> Bob Camp wrote:
>>> In this paper:
>>> TOTAL HADAMARD VARIANCE: APPLICATION TO CLOCK STEERING BY KALMAN
>>> FILTERING by Dave Howe , Ron Beard , Chuck Greenhall , Franc Ì§ois
>>> Vernotte and Bill Riley
>>> Figure 2 actually refers to:
>>> Navstar Quarterly Report 00-3, Space Application Branch, NRL, Wash D.C.
>>> 20 July 2000.
>>> The report apparently describes the level of variance on the various
>>> GPS satellites versus tau for the first half of 2000. Bottom line
>>> appears to be that 5x10^-13 is about as good as it gets out to 20 day
>>> tau unless you can pick your sats. Obviously this data is a bit dated.
>>> Is this data updated on a regular basis? Is it published somewhere?
>>> Can one get a look at it without risking a long term stay in Federal
>>> prison? It certainly would be useful to those trying to tweak GPSDO's.
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