[time-nuts] GPS Sat Clock Data
lists at rtty.us
Fri Jun 4 10:59:59 UTC 2010
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.
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.
>> 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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