Hi there!
I have some questions about the GPS satellites and the Sagnac effect.
Assume we have three clocks on the Earth, A, B, and C. A is sent west
at v m/s, B stays at the ground, and C travels east at v m/s. v is the
rotation of the Earth around its own axis. Assume v = 464 m/s and the
experiment is done at the equator. According to my knowledge, A, B and
C will all show different time when they meet again after traveled
around the Earth. Please correct me if I am wrong. A is in an Earth
centered inirtial frame (ECI), B is in an Earth centered Earth fixed
frame (ECEF). We can calculate the Sagnac effect, so that should not
be a problem I assume. Now, we increase the radius of clocks A, B and
C so they assume the same radius as the GPS satellites from Earth.
Will there still be a Sagnac effect? Another question, if we increase
the velocity of clocks A and C so they travel at the same speed and at
the same radius as the GPS satellites, will there be a Sagnac effect
even in this case? If not, why so?

/morpheus