[time-nuts] Did a member of time-nuts buy this?
kb8tq at n1k.org
Thu Dec 11 07:31:41 EST 2014
> On Dec 11, 2014, at 3:35 AM, Brian Inglis <Brian.Inglis at SystematicSw.ab.ca> wrote:
> On 2014-12-09 04:10, Mike Monett wrote:
>>> One very cute addition would be to pull down the NIST GPS data and
>>> use it to correct your system on an hourly / daily basis. If you
>>> do that with common view satellites, you most certainly will beat
>>> a surplus grade Cs standard.
>> How can we do this? The NIST archives state
>> "The archive is only updated once every 24 hours, so data are not
>> available for today's date. Data from the previous day are added to
>> the archive at about 1600 UTC."
>> Is there another page that has current data? If so, how do we
>> incorporate it into the GPSDO?
> IGS http://igscb.jpl.nasa.gov/components/data.html has pointers to
> get 15 minute samples from high rate IGS stations around the world:
The question is what level of timing those stations have (and thus traceability to UTC).
> USNO info tells you which SVNs/PRNs have Cs (few) and Rb (most) clocks:
> might be interesting to compare accuracy of Cs vs Rb SVs in view.
There are several papers on the base clocks on the GPS sat’s. The simple answer appears to be that they correct them from the ground more often than is needed with any of them. Thus the ground segment “stability” is the main issue. Their correction process is far from simple so sorting everything out is a major effort. The driver for very fancy clocks is as much a bunch of “what if?” type failures as an absolute need in normal operation.
> Take care. Thanks, Brian Inglis
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