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GPS work boosts signal for construction

A Block III GPS satellite orbits the Earth in an artist’s rendering. The new generation of satellites will improve the accuracy of military and civilian GPS receivers. (AP image by Lockheed Martin)

Dan Elliott
Associated Press

Jim Keyser, manager of Lockheed Martin’s GPS Processing Facility, stands next to a prototype of the propulsion core for a Block III satellite at the assembly plant. (AP photo by Lockheed Martin)

DENVER — The future of the U.S. Global Positioning System is taking shape in a vast white room south of Denver, where workers are piecing together the first of more than 30 satellites touted as the most powerful, reliable and versatile yet.

The new generation of satellites, known as Block III, will improve the accuracy of military and civilian GPS receivers to within 3 feet, compared with 10 feet now, according to the Congressional Budget Office.

Block III also will have additional signals for civilian use — one brand new, others already in the first stages of deployment — offering more precision and making more navigation satellites available to civilian receivers.

“It’s a really big jump,” said Col. Harold Martin of the Air Force Space Command. “With these additional signals, the additional power it’s going to bring, it’s quite a leap from the other systems.”

Block III might not be a bigger advance than previous generations of GPS satellites were, said Glen Gibbons, editor of the website and magazine Inside GNSS, which tracks global navigation satellite systems.

“But I’m completely comfortable saying that it will be a very substantive advance,” according to an email attributed to Gibbons.

GPS has spread into nearly every corner of civilian and military life. Construction contractors use it for measuring grading, elevation, staking, mapping and site exploration. Banks use it to record the precise time of transactions. It has found wide use in transportation, guided weapons, emergency response and disaster relief.

Block III satellites, which will begin replacing older orbiting GPS satellites in 2014, offer a new, internationally agreed-upon civilian signal that other nations’ navigation satellites also will use.

That would let civilian receivers tap into Europe’s budding Galileo navigation system and others.

“So all of a sudden you’ve got 70, 80, 90 satellites up in orbit,” compared with 30 operational satellites in the U.S. system today, Gibbons said in an interview. “It’s giving you a much greater number of satellites to be receiving.”

GPS receivers need signals from at least four satellites to establish a position, so having more satellites to tune into would improve accuracy. It also makes it easier for a receiver to find enough satellites.

Block III will add to the number of satellites transmitting to other relatively new civilian signals. One likely will be used for such high-precision activities as surveying, Gibbons said.

It’s not clear when enough satellites will be transmitting the international signal and the other new civilian signals to make them usable. It typically takes 18 satellites transmitting a signal to reach initial operation and 24 to reach full capability, Gibbons said.

Block III also will widen the availability of two new, encrypted military-only signals already being transmitted from a few satellites. The Air Force reports they will have more power than older military signals, making them harder for enemies to jam and letting them penetrate deeper into urban canyons formed by skyscrapers.

The Air Force, which controls all the U.S. GPS satellites from Schriever Air Force Base, Colo., plans to buy and launch 32 of the new Block III satellites over several years at a cost of about $5.5 billion, including upgraded ground control systems.

The Congressional Budget Office, which issued a report on GPS in October, estimated the total costs much higher — $22 billion by 2025 — in part because CBO reports the Air Force will need 40 satellites, not 32, to take advantage of all the capabilities planned for later GPS III models.

Bethesda, Md.-based Lockheed Martin was awarded a $1.5 billion contract to build a nonflying prototype of the GPS III satellites and the first two flight versions, with options to build 10 more.

The last component of the prototype recently arrived at Lockheed Martin’s $80 million GPS facility south of Denver. In a sparkling white clean room nearly as big as a football field, it will undergo final assembly and months of testing designed to find and correct any problems before workers make it into any flying satellites.

The prototype also will help find any bugs in the assembly and testing process, said Keoki Jackson, Lockheed Martin’s program director for GPS III.

“It allows us to find any issues long before they become any issues with flight hardware,” he said.

The Air Force eventually plans to begin launching two GPS III satellites on the same rocket, Jackson said. A satellite launch typically costs about $250 million, and doubling up will bring significant savings, he said.

GPS III satellites are designed to operate for 15 years, compared with seven to 12 years for many military satellites, Jackson said.

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