DARPA to develop GPS-free microchip navigation

Atomic clock-on-a-chip would help soldiers, weapons find their way without shortcomings of satellites

The U.S. military’s weapons and communications systems rely on global positioning data to determine their locations. But satellite navigation systems are becoming more susceptible to jamming during a conflict.

To meet this challenge, the Defense Department’s research and development arm has launched a program to develop new technologies that would allow military gear to function and to know its location without the benefit of Global Positioning Satellite signals.

One of the main goals of the Defense Advanced Research Projects Agency’s Micro-Technology for Positioning, Navigation, and Timing (Micro-PNT) program is to develop an inertial navigation and timing unit that will fit on a microchip. State-of-the-art systems are now about the size of an apple.

“We want to get this down to the size of an apple seed,” said Andrei Shkel, Micro-PNT’s program manager.

To achieve GPS-free navigation, Micro-PNT has brought several DARPA programs together to provide a single-chip system. These subsidiary programs are at various levels of development, but the most mature part of the program is the Chip Scale Atomic Clock (CSAC), which was itself part of an intensive DARPA development effort and is now a commercially available product. Atomic clocks are used to keep very exact time. Prior to the CSAC program, the smallest devices were about the size of a microwave oven. CSAC successfully reduced this to the size of a sugar cube. If Micro-PNT can make atomic clocks even smaller, they will begin to be installed on a variety of electronics, such as handheld computers and smart phones.

This would have a major effect on personal navigation because the devices would be able to continue tracking their location even when GPS signals are unavailable, Shkel said.

Replacing GPS navigation is a challenge because it is so vital to how the military navigates. Many missiles use GPS to find their targets. The projectiles also have very short flight times—under three minutes in most cases. But many high-value targets now use a variety of defensive jamming systems, Shkel said. One of Micro-PNT’s goals is to replace GPS navigation for these guided weapons.

As for communications and navigation gear used by soldiers, there are times and places where GPS signal cannot be accessed, such as inside large buildings and caves. In addition to operating in those environments, an independent system would shorten the time required for handheld communications and navigation systems to reacquire GPS signals, he said.

The Micro-PNT program is also developing chip-based gyroscopes that may replace fiber-optic gyros now in use. In addition, the program is examining new types of high-performance gyroscopes—wine-glass-sized devices that are currently very expensive to make and manufacture. In doing so, researchers are studying ancient glass-blowing techniques to create miniaturized, highly accurate navigation systems that could potentially replace GPS on a variety of systems, such as the Joint Direct Attack Munitions (JDAM) kits used to turn unguided bombs into precision munitions, Shkel said.

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