- #1
cianfa72
- 2,352
- 253
- TL;DR Summary
- About physical process involved to synchronize GPS clocks in Earth Centered Inertial (ECI) frame
Hi,
starting from this old thread GPS clock synchronization I've a doubt about the physical process employed to synchronize clocks bolted on GPS system satellites.
We said that clock synchronization is frame dependent. In other words we must select a coordinate chart (aka reference frame) that implicitly defines the notion of 'the same time ##t##' in that specific frame.
On the other hand each physical clock follows its own timelike worldline through spacetime, so we can ask: at a given coordinate time ##t## in the chosen coordinate chart (frame) which is the value of its own proper time read (or shown) from each physical clock ? By definition physical clocks are synchronized -- w.r.t. the chosen coordinate chart -- if in the above scenario they read (show) the same value.
So far, so good...coming back to the topic of thread: in the referenced thread we said that bolted clocks on GPS satellites
My question is: which is the process involved to synchronize (and keep synchronized) them in the ECI frame ?
starting from this old thread GPS clock synchronization I've a doubt about the physical process employed to synchronize clocks bolted on GPS system satellites.
We said that clock synchronization is frame dependent. In other words we must select a coordinate chart (aka reference frame) that implicitly defines the notion of 'the same time ##t##' in that specific frame.
On the other hand each physical clock follows its own timelike worldline through spacetime, so we can ask: at a given coordinate time ##t## in the chosen coordinate chart (frame) which is the value of its own proper time read (or shown) from each physical clock ? By definition physical clocks are synchronized -- w.r.t. the chosen coordinate chart -- if in the above scenario they read (show) the same value.
So far, so good...coming back to the topic of thread: in the referenced thread we said that bolted clocks on GPS satellites
are and remain synchronized in the ECI frame so there is never any difference in timing in the ECI frame between any pair at any time in the ECI frame. They don't drift apart in the ECI frame, ever.
My question is: which is the process involved to synchronize (and keep synchronized) them in the ECI frame ?