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Space

Army develops improved Global Positioning System

by Stephen Larsen

FORT MONMOUTH, N.J. (Army News Service, Sept. 15, 1998) -- The movie "2001: A Space Odyssey" was Stanley Kubrick's vision of what could happen between man and machine among the stars in the new millennium.

Lt. Col. Joe Lofgren of the U.S. Army Communications-Electronics Command sees next century's soldiers finding their way on the digitized battlefield by receiving satellite signals on hand-held Defense Advanced Global Positioning System Receivers, day or night.

"We plan to start putting DAGR's in the field in 2001," said Lofgren, the CECOM Systems Management Center's Product Manager for GPS.

Lofgren said that the DAGR, being developed in partnership with the GPS Joint Program Office in Los Angeles, Calif., will replace the Precision Lightweight GPS Receivers (PLGR, pronounced "plugger") of which about 78,000 are currently in Army field units.

PLGR's are used hand-held by infantry units and mounted in tracked and wheeled vehicles, aircraft and watercraft to provide real-time, precise location data and to provide a common time-source for synchronizing systems.

Lofgren said DAGR would include the same GPS position, velocity and time information currently available with the PLGR, along with cutting-edge GPS and digital technologies. One of the new "user-friendly" features of the DAGR will be a graphical user interface.

"A map will come up on the screen," said Lofgren. "Your present location will be indicated on a digitally displayed map. You enter a destination waypoint and an azimuth and heading pointer lead you to it."

The DAGR will include enhanced navigation and cryptographic features, according to Lofgren. These features include:

  • The ability to use GPS frequencies for better position accuracy;
  • All-in-view capability that allows the receiver to select the best satellites available at a given time;
  • Advanced electronics that speed up signal acquisition time;
  • Enhanced antennas and filters to address GPS vulnerability to jamming and spoofing (opposing forces' ability to throw GPS off-course via false signals).

While the PLGR weighs 2.75 pounds, the DAGR weighs less than 2 pounds.

"The goal is to make it small enough and light enough to fit in a BDU [Battle Dress Uniform) pocket," Lofgren said.

Since the size of the unit is driven by battery size, he said, the DAGR is being designed to use small, readily available AA batteries.

"We're working with the CECOM Power Management Center of Excellence to provide the most efficient use of power possible," Lofgren said. He added that the DAGR will be usable in either hand - "the PLGR is designed for left-hand use, only," he said.

Besides developing the DAGR, Lofgren said, Army technicians are working on the GPS Receiver Applications Module (GRAM), and the GPS Inertial Navigation System (GPS/INS).

The GRAM will be "GPS on a card," Lofgren said, which features the full functionality of a precision GPS receiver on a standard bus card.

"This will give users the ability to embed GPS receivers in the electronics of HMMWVs, tanks, helicopters and so on ... saving space and weight," he said. Since the GRAM will use an open architecture, future upgrades will be implemented by simply replacing the GRAM card.

"Many platforms will be capable of using the same card, thus reducing the cost of the card by encouraging economies of scale," Lofgren said.

GPS/INS is a merging of technologies for use in big-ticket, mission-critical systems such as the Multiple Launch Rocket System, Abrams tank and Apache helicopters, according to Lofgren.

"This is a perfect marriage of GPS and INS technology," he said. "If GPS is taken out (jammed), the INS will provide a heading of where you're going, since it can't be jammed. On the other hand, INS tends to drift over time, and GPS corrects it, real-time, as often as needed."

Some have projected that INS' cost could drive the ticket price for GPS/INS to about $60,000 to $70,000 per system. Lofgren cautiously predicts that figure will drop, thanks to the work of the Defense Advanced Research Projects Agency in developing the GPS Guidance Package, a GPS/INS hybrid for use on precision guided munitions.

"DARPA has proven-out, on paper, that they can combine GPS and INS for around $15,000; so we think we can drop the dollars further," he said.

Lofgren said that PM GPS currently has the money to field an estimated 66,000 DAGR's between 2001 and 2005 - however, his tally of requirements from the field is for 250,000 units. "We'll start (fielding) by hitting high priority units, and continue to refine the requirements for DAGR's and request dollars as required," he said. He added, though there is no money programmed by the Army for GRAM and GPS/INS, he is confident that through the Army's Horizontal Technical Integration (HTI) program, and the associated partnership with battlefield systems platform managers that HTI encourages, there will be money to acquire and field these products.

"By 2006, we should have a fully integrated mix of around 800,000

GPS products in the field," said Lofgren, "very robust, tied into the digitized Army. We can get there from here."

Lofgren paused, then thought of the job ahead of him. "It's space-related, and it's definitely an odyssey," he said.

(Editor's note: Larsen works with U.S. Army Communications-Electronics Command.)

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