GPS overhaul will add signals for civilian use

The Clinton administration last month launched a six-year, $400 million initiative to
modernize the Defense Department’s Global Positioning System.


The upgrade would add two new civilian signals to future GPS satellites to improve
services provided to millions of non-DOD users worldwide.


GPS is a constellation of 24 satellites developed, launched and maintained by the Air
Force. The system gives users positioning, timing and navigation signals free of charge
and helps guide airplanes, trains, ships, cars, tractors and surveying and mining
equipment by providing immediate, accurate location data anywhere on Earth.


The addition of second and third civilian frequencies will enhance the accuracy,
reliability and robustness of civilian GPS receivers by letting them make more effective
corrections for the distorting effects of the Earth’s atmosphere on the signals, DOD
officials said. The new signals will also give users a backup signal if there is a
disruption of the current civilian signal.


GPS supplies signals on two frequencies to military users. The goal is to provide
civilian users with signals on three frequencies by 2005.


“The United States is proud to be a leader in the development of the Global
Positioning System—a wonderful example of how technology is benefiting our citizens
and people around the world,” Vice President Al Gore said when announcing the
administration’s plan.


“This initiative represents a major milestone in the evolution of GPS as a global
information utility and will help us realize the full benefits of this technology in the
next millennium,” he said.


Gore’s White House Commission on Aviation Safety and Security, among other groups,
in recent years recommended the addition of more civilian GPS signals.


DOD and the Transportation Department, which run the Interagency GPS Executive Board,
decide which GPS frequencies


to provide to civilian users. The current civilian signal is 1575.42 MHz.


The second civilian signal will be at 1227.60 MHz along with one of the two military
signals. It will be available for general use for non-safety-critical applications. The
new signal will be implemented on GPS satellites slated for launch beginning in 2003.


The third civilian signal—known as the safety-of-life service signal—will be
1176.45 MHz, within a portion of the frequency spectrum that is allocated internationally
for aeronautical radio navigation services. The signal will be implemented beginning with
a satellite scheduled for launch in 2005.


The new signals will be added to six GPS satellites that Boeing Co. will build for DOD.



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