Re: System.Time.Clock Design Issues

On Feb 6, 2005, at 7:18 PM, Ashley Yakeley wrote:

In article <83fcd29a8070c7a77db3b2f01bbaac71@comcast.net>, Gregory Wright wrote:

...

Raw GPS time (the number of seconds since the GPS epoch) is broadcast in a complicated form in the satellites' navigation message, along with the current number of UTC leap seconds since the GPS epoch. From the raw GPS time and the number of leap seconds UTC can be calculated.

So there's some way that the satellites get told about leap seconds when they're announced?

Yes, the GPS satellites have the next scheduled leap second insertion uploaded. They begin broadcasting the new leap second count when the scheduled leap second occurs. The navigation messages of the GPS satellites are frequently updated with the latest orbital parameters of the satellites, among other things. This is necessary because the gravitational perturbations of the moon and sun, and the higher multipole moments of the Earth's gravitational field slowly alter the orbits. Greg

-- Ashley Yakeley, Seattle WA

_______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries