President orders elimination of 'fudge factor' in satellite positioning system

President orders elimination of 'fudge factor' in satellite positioning system

By William Jackson

GCN Staff

MAY 2'Civilian users of the Defense Department's Global Positioning System will see up to a ten-fold increase in the accuracy of the satellite system beginning today, when the government quits distorting the signal available to non-military users.

President Clinton yesterday ordered a halt to selective availability, the process of degrading the GPS satellite signals used by millions around the world to establish geographic locations. Now equipment that previously determined position to within 100 yards can determine it to within 20 yards. A White House statement said the decision should encourage use of GPS by the automotive, cellular phone and marine industries.

GPS is a military satellite system that enables ground-based receiving equipment to determine geographic location. The government has made the signal and receiver technology freely accessible, and selective availability is a security measure to give U.S. forces an edge in accuracy over enemy forces using the technology.

A 1996 Presidential Decision Directive announced the administration's intention to encourage use of GPS by eliminating selective availability. It was determined that the government's capability to selectively deny GPS signals on a regional basis would allow it to abandon selective availability with no risk to national security.

GPS is widely used by boaters and in autos for navigation and emergency signaling. The FCC soon will require all new cellular phones to have accurate location technology to improve responses to emergency calls. Removing selective availability could make GPS the method of choice for implementing this.

The accuracy of time broadcasts by GPS also will be improved to within 40 billionths of a second, making it practical for synchronization of global systems.


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