New GPS Receivers Built To Bust Jamming
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Written by Bradley S. Melara
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Monday, 09 March 2009 |
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One of the biggest fears of the open-access environment of Global Positioning System C/A Code is the possibility for enemies to access the GPS code, jam it, or use it against the U.S. C/A code is available to anyone in the world, including civil users and foreign militaries.
C/A code, which the Defense Department degrades intentionally, intentionally, enables users to navigate with only 100-meter accuracy. Yet weapons of mass destruction such as chemical or biological weapons with C/A code GPS guidance systems pose a threat.
Just as sobering, there is a potential for adversaries to use GPS for cruise missile guidance, according to several studies, including one by The Critical Technologies Institute in Santa Monica, Calif.
The Critical Technologies study says the U.S. military would be forced to jam its own GPS signal to deny that capability to its adversaries. By doing this, "even though the enemy still has their cruise missiles, they can't get precision navigation for free anymore," explains Tyler Trickey, marketing manager of navigation products at the Rockwell International Collins Avionics and Communications Division in Cedar Rapids, Iowa.
Without U.S.-supplied GPS signals, potential adversaries "have to invent their own terrain contour maps and invest in $100,000-highly precise inertial navigators," Trickey says. "That is a very limited and expensive kind of technology."
The DOD is pushing to make military GPS more robust so that it can function in jamming and spoofing, Trickey says. Rockwell-Collins is looking at several ways to provide anti-jam capability, such as receivers with direct encrypted Y code capability and solutions within the receiver that help overcome interference.
Rockwell-Collins is also developing an anti-jam antenna array for armored combat [*]vehicles, which hasn't been available on the ground before. An anti-jam non-steer antenna array has been used previously for aircraft such as the B-52 bomber and the F-16 fighter.
Honeywell is also improving resistance to jamming. "When and INS [inertia navigation system] is tightly coupled with GPS, the inertial data aids the GPS tracking loops and provides a better immunity to jamming," explains David C. Moya, strategic product manager at Honeywell's Guidance and Navigation operation in Clearwater, Fla.
Mangavox Electronic Systems Co. in Torrance, Calif., has developed a jam-resistant, nuller-receiver, for acquisition and tracking of GPS signals. Mangavox officials claim this device, which has been integrated with an inertial navigation unit developed by Litton for use on the Tomahawk Block IV Missile, is the most jam-resistant receiver available.
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Last Updated ( Monday, 09 March 2009 )
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Vehicle GPS Unit