Global Positioning
System, an accurate
worldwide
navigational and
surveying facility
based on the
reception of signals
History
The first satellite navigation system, Transit, used by the
United States Navy, was first successfully tested in
1960. It used a constellation of five satellites and could
provide a navigational fix approximately once per hour.
In 1967, the U.S. Navy developed the Timation satellite
that proved the ability to place accurate clocks in space,
a technology required by GPS. In the 1970s, the
ground-based Omega Navigation System, based on
phase comparison of signal transmission from pairs of
stations,[10] became the first worldwide radio navigation
system. Limitations of these systems drove the need for
a more universal navigation solution with greater
accuracy