The US GPS satellite constellation (NAVSTAR) is not purely navigational, nor one way. This is not to say that your user receiver is sending it's position to anyone, it doesn't, but that the network is not unidirectional, and not single tasked. Only a subset of the function is described publicly, or in patents, and additional features are added with each new generation. I'd be willing to bet the classified features are even more interesting.
While it supports the course/acquisition (1.023 MHz) and precision military (10.23 MHz) timing/positional signals, there is also support for nuclear detonation, and missile launch detection, and a secure global paging system. Ground stations can communicate with the satellites, and the satellites can communicate with each other. So it is a little more complicated than a clock in space, that knows it's location.
The satellites contain more than one atomic clock (at least 3-4), the cesium ones being more accurate than the rubidium ones.
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The US GPS satellite constellation (NAVSTAR) is not purely navigational, nor one way. This is not to say that your user receiver is sending it's position to anyone, it doesn't, but that the network is not unidirectional, and not single tasked. Only a subset of the function is described publicly, or in patents, and additional features are added with each new generation. I'd be willing to bet the classified features are even more interesting.
While it supports the course/acquisition (1.023 MHz) and precision military (10.23 MHz) timing/positional signals, there is also support for nuclear detonation, and missile launch detection, and a secure global paging system. Ground stations can communicate with the satellites, and the satellites can communicate with each other. So it is a little more complicated than a clock in space, that knows it's location.
The satellites contain more than one atomic clock (at least 3-4), the cesium ones being more accurate than the rubidium ones.