Positioning using Television Signals

Via SiliconValley.com, a Redwood City start-up is prototyping a system that uses TV signal to do positioning. The goal is to embed it in mobile phones. I would work more or less the same way as other radio frequency positioning:

The engineers created a radio receiver chip that could zero in on the TV signal and get the synchronization information. Using precision timing, they figure out how far a TV signal travels before it is picked up by a device equipped with Rosum chips. Next, they compare the measurements against other data that they collect with their own listening stations and then finally calculate the device’s position. The Rosum engineers call this process “multilateration,” which is akin to navigational triangulation.