[time-nuts] Coalition to Save GPS

[Magnus Danielson]

On 03/14/2011 12:06 AM, J. Forster wrote:
> I don't know what portion of all the GPS receivers deployed by the DoD now
> have direct-P(Y)-acquisition capability.

If they would be forced to shift in direct-P(Y) earlier if LightSquared 
caused them trouble, then it would hurt a bit, but I would expect it to 
be acceleration of a shift-program they need to do anyway.

> Fundamental to direct-P(Y) acquisition is a priori clock synchronization.
> If too much time has elapsed since a receiver had a GPS satellite in view,
> then the receiver's local clock may have drifted so far that the receiver
> would need an unacceptably long time to search far enough in epoch-offset
> to find a P(Y) signal.  Therefore, a direct-P(Y) receiver may need to be
> synchronized by external or extraordinary means, such as a portable atomic
> clock or a cable or radio link to an atomic clock.  Nowadays, the military
> is so extensively networked (for a variety of reasons) that the
> requirement for external synchronization is not terribly burdensome.

Another already locked receiver would do just fine.

Cheers,
Magnus