Page 54 - Electronic Navigation Cyber Book

exploited to create a truly accurate global positioning system, free from
many of the constraints of the existing earth-bound hyperbolic

navigation systems.

The first commercially available system to be developed, the Navy
Navigation Satellite System (NNSS), made good use of the Doppler
effect and provided the world's shipping with precise position fixing for
decades. However, nothing lasts forever. The technology became old

and the system was dropped on 31 December 1996 in favor of the vastly
superior Global Positioning System (GPS). Although a number of NNSS
Nova satellites are still in orbit, the system is no longer used for

commercial navigation purposes. Advances in technology and new
demands on the existing system have now led to efforts to modernize the
GPS system and implement the next generation of GPS III satellites and
Next Generation Operational Control System (OCX). Announcements
from Vice President Al Gore and the White House in 1998 initiated these

changes. In 2000, the U.S. Congress authorized the modernization
effort, GPS III.

In addition to GPS, other systems are in use or under development. The
Russian Global Navigation Satellite System (GLONASS) was developed
contemporaneously with GPS, but suffered from incomplete coverage of

the globe until the mid-2000s. There are also the planned European
Union Galileo positioning system, India's Indian Regional Navigational
Satellite System and Chinese Compass navigation system.

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