[time-nuts] seeking a time/clock software architecture
albertson.chris at gmail.com
Fri Sep 23 21:24:26 UTC 2011
On Fri, Sep 23, 2011 at 12:32 PM, Jim Lux <jimlux at earthlink.net> wrote:
> On 9/23/11 10:50 AM, Chris Albertson wrote:
> Yes, in the general case, but in the spacecraft case, I think we're more
> concerned about smoothness and such over time spans of days, maybe weeks and
> More about establishing time correlation between multiple radios/spacecraft
> in a constellation, for instance.
I think better to have your system be usable in the "real world" and
then the spacecraft to use "real world" standards when it can. If it
can handle the ful general case then it will work in the spacecraft
too. So Chinese lunar calenders are a good mental exercise. At any
rate piece wise 2nd order polynomial will work in all cases I can
think of because you can always make the pieces really small if need
be to the point where it becomes a table look up.
Spacecraft spend a fair amount of time on the ground in testing.
People swap out parts. I work in telemetry and you should see the
database of tens of thousands of polynomial functions that must be
used to process data. from say a DeltaIV. It's not only clocks but
dozens of sensors that get changed out in the months preceding launch.
Redondo Beach, California
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