[time-nuts] GPS Sat Clock Data

[Bob Camp]

Hi

There have been "hardware" papers every few years showing this and that about the clocks. They obviously have access to some sort of database that lets them generate the data. I guess the database is  "off limits" to civilians. 

Bob


On Jun 4, 2010, at 1:10 AM, bg at lysator.liu.se wrote:

> Hi Bob,
> 
> 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.
> 
>   http://www.ion.org/search/search_proceedings.cfm
> 
> --
> 
>   Björn
> 
>> Hi
>> 
>> 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.
>> 
>> Thanks!
>> 
>> Bob
>> 
>> 
>> On Jun 3, 2010, at 9:54 PM, Brian Kirby wrote:
>> 
>>> I do not know if this is what your looking for,
>>> http://www.nist.gov/physlab/div847/grp40/gpsarchive.cfm
>>> 
>>> follow the directions on the date....
>>> 
>>> You can look at individual SVN performance, etc.
>>> 
>>> Bob Camp wrote:
>>>> Hi
>>>> In this paper:
>>>> TOTAL HADAMARD VARIANCE: APPLICATION TO CLOCK STEERING BY KALMAN
>>>> FILTERING by Dave Howe , Ron Beard , Chuck Greenhall , Franc ̧ois
>>>> Vernotte	and Bill Riley
>>>> http://tf.nist.gov/general/pdf/1459.pdf
>>>> 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.
>>>> Bob
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>> 
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> 
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