Could a GPS device reveal my location to others?

Not unless you want it to…

By Deborah Halber

Not unless you want it to, according to Seth Teller, professor of computer science and electrical engineering. Whether you want it to or not depends on whether you’re a teenager evading nosy parents or in a broken-down car on a lonely country road.

“An ordinary Global Positioning System (GPS) receiver, such as those found in commercial dashboard navigation systems, will not reveal your location to others,” Teller said. “All GPS receivers receive signals from orbiting satellites and use those signals to compute the receiver’s location on Earth. But that computation is performed locally, on the receiver, so does not inherently reveal your location to anyone else.”

Teller notes that users concerned with privacy should be aware that most GPS devices, for example dashboard-mounted vehicle navigation systems, record a series of time-stamped locations as the device moves through the world. Rental-car companies have used such GPS traces as evidence of contract violations (such as excessive speed or driving outside of a specified region), and prosecutors have gathered GPS records to show the presence of vehicles near crime scenes. Some commercial services, such as GM’s OnStar, automatically transmit location data to the company in case of an accident or request for assistance. And many GPS devices can be configured to transmit real-time location information, for example to track shuttle buses (as at MIT), monitor your children’s whereabouts, or simply let your friends know where you are.

Teller’s group uses GPS devices in the development of outdoor autonomous mobile robots such as the self-driving Landrover LR3 that MIT entered into DARPA’s recent Urban Grand Challenge competition.

Posted: December 12, 2008