"LARGE AND SMALL RELATIVISTIC EFFECTS IN THE GLOBAL POSITIONING SYSTEM"
The Global Positioning System (GPS) relies more on fundamental
physical principles than any other large existing engineering system.
In particular, relativity principles, such as the constancy of the speed
of light and the equivalence principle, must be carefully accounted
for in order for the system to work. Time dilation and gravitational
frequency shifts are consequences of relativity which are about 10,000
times too large to ignore in the GPS. This talk will review relativistic
effects arising from earth and satellite motion, monopole and quadrupole
gravitational fields of the earth, and will discuss how these effects are
incorporated into the Space and User Segments. Recently discovered
relativistic frequency breaks, due to orbit adjustments, will be explained.
Several small relativistic effects which are not yet incorporated, but
which may become important in the future, will be discussed.