UK researchers are looking at using cheap, but incredibly accurate atomic clocks to fill in the coverage gaps when GPS is unavailable. The quantum timing technology is quite nascent but one day might be even find a home in cellular base stations to keep them running when GPS signals fail.
The technology is being developed by civilian researchers in collaboration with Britain's Defense Science and Technology Laboratory (DSTL). The atomic clock they have created can also be used to sense the earth's gravitational and magnetic fields. Comparing the sensor's measurements with a previously constructed map of the earth's gravitational field enables accurate position determination of a person.
The technology could also enable troops to see behind obstacles, Bob Cockshott, a positioning, navigation and timing expert at the UK's National Physical Laboratory, told The Wall Street Journal. "By determining what is exerting gravity on the other side of the wall, you would have something that could literally see through walls," he said.
The current device measures three cubic feet but could be reduced to suitcase-size in two years. Unlike GPS, a quantum timing device cannot be spoofed or tampered with using current technology. "You can't interfere with the gravitational field," Cockshott said.
GPS provides timing for synchronization of base stations, enabling mobile handsets to share limited radio spectrum more efficiently. But the approach is not foolproof because GPS signals can be lost for a variety of reasons. Providing quantum timing as a fallback could eventually prove useful, particularly in areas where GPS service is iffy.
GPS is also used in many location-based services, though companies are increasingly searching for better alternatives indoors, where GPS has trouble reaching.
- see this Wall Street Journal article (sub. req.)