A British company is working on a new navigation system that doesn't rely on GPS satellites to track your location. BAE has created Navsop, a device that picks up errant cell phone, radio and television signals to deduce your coordinates, which means it can be used in locations where traditional GPS can't. For example, TV signals are substantially more powerful in buildings and below ground than GPS, which means Navsop could eventually help locate individuals in collapsed buildings or mines. It could also be instrumental in locating stolen vehicles stashed in underground parking garages.
BAE claims that while Navsop is still in the early stages of development, it will eventually fit into a gadget about the size of a standard coin. At present, however, Navsop resides in a massive box that must be lugged around in a car and attached to a whip antenna. Not exactly smartphone compatible.
Navsop isn't entirely independent from GPS, however. The system must first get its bearings from the satellites in the sky before turning to radio signals.