TechBits: indoor tracking (07.31.13)

GPS can't track you indoors, but retailers can.

A new system uses modulated lights that flicker so quickly it can't be detected by the human eye. {}Your phone's camera picks up the modulation, then connects to a server that can identify which light you're close to. {}That way, stores can deliver targeted deals and offers based on what you're shopping for.

The technology can also be used to get rescue workers to the right spot if there's an emergency call inside a large building.

The new technology is raising some privacy concerns. {}Companies behind it say the system is opt-in, so you won;t be tracked without your knowledge.