Technical problems are degrading the accuracy of signals from the last GPS satellite launched by the Pentagon, sparking concerns among U.S. military and aerospace industry officials that the next generation of the widely used satellites could face similar troubles.

The next generation of the widely used satellites could face similar troubles.

The Air Force's Southern California space acquisition center on Tuesday announced that a Global Positioning System satellite, manufactured by Lockheed Martin Corp. and launched in March, is experiencing performance problems in orbit. It hasn't become part of the "operational constellation" of more than two dozen other GPS satellites, and is slated to undergo a battery of tests expected to stretch through October to try to resolve the problems, according to an Air Force news release.

The GPS system, which serves both military and civilian users, provides precise time and location coordinates for everything from military missile launches and "smart" bombs to automated bank-teller machines to aircraft, ships and everyday vehicles. The Lockheed satellite is the first to include a new civilian frequency — dubbed L5 — designed for, among other things, use by future nationwide air-traffic control systems. But that signal, part of test package, apparently is interfering with other signals from the satellite and reducing their accuracy, according to industry and Air Force officials. The degraded signals are accurate only to about 20 feet, versus about two feet for typical GPS signals, industry officials said.

The issue is significant, according to these officials, because it could complicate deployment of a new family of Boeing Co. GPS satellites currently being built that also feature the L5 signal. Already years behind schedule and hundreds of millions of dollars over budget, the 12 satellites, which are scheduled to replace satellites currently in orbit, could face further testing and delays to ensure that they are free of interference problems. The Boeing satellites have a history of quality-control and manufacturing problems unrelated to the latest concerns.

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