Civil GPS accuracy boosted

President Clinton on Monday delivered on a 4-year-old promise to improve

the accuracy of the Global Positioning System to civil users.

In a presidential directive in 1996, Clinton promised to revisit the issue

of intentionally degrading the civil GPS signal in 2000. He had promised

to discontinue use of the degradation capability — known as selective availability — by 2006, with an annual assessment of its continued use beginning this


Selective availability was deactivated at midnight on Monday, the president's

science adviser, Neal Lane, announced during a press briefing earlier in

the day.

The decision came early because the Defense Department has sufficiently

proven its ability to deny the GPS signal to adversaries in a specific region

while maintaining availability to users elsewhere, said Arthur Money, the

Pentagon's assistant secretary of Defense for command, control, communications

and intelligence.

Selective availability caused the civil GPS signal to be accurate within

100 meters. Without selective availability, users will receive position

information accurate within 10 to 20 meters.

While the modification significantly improves the accuracy of the GPS signal,

the Transportation Department is still committed to developing systems that

augment the GPS capability, said Eugene Conti, assistant secretary of Transportation

for transportation policy. Those systems, such as the Federal Aviation Administration's

Wide-Area Augmentation System and Local-Area Augmentation System and the

Coast Guard's National Differential GPS System, verify that the GPS signal

is reliable.


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