Re: Re: Question on GPS systems
as to the second part of the question (if I understand your question correctly), I don't think there is a director coordinating signals between the satellites and the gps units. The unit itself has enough brains to take 3 signals and figure out its location from just the signals. Communication is top-down only for your run of the mill gps unit.
That being said, I'm sure the satellite owners do communicate directly with them and could turn off the signal at their pleasure.