(via telecom-cities), an interesting way to remove some of the drawbacks of GPS signals (or the lack of GPS signals): Television Signals Plug the Holes in GPS by Jason Daley

Today’s Global Positioning System is great for tracking tanks in the desert, but turn on your Garmin in New York City or inside virtually any building, and you’ll be staring at satellite static—GPS doesn’t perform well indoors or in urban canyons. Now a new technology is poised to pick up where GPS satellite signals cut out.

Developed by Rosum Corporation in Redwood City, California, TV-GPS, as the system is known, triangulates positions using television signals that are 2,000 times as strong as GPS satellite transmissions. With nearly 2,800 TV antennas concentrated mainly in U.S. metropolitan areas, where GPS coverage is weakest, TV-GPS has a ready-made infrastructure.