Tapping TV Signals: Charles River Adds to Investment in Rosum

4/16/08Follow @wroush

The Global Positioning System helps millions find their way around the surface of the planet every day. But if you’ve ever walked around with a handheld GPS unit, you know that the radio signals transmitted by GPS satellites are so weak that they’re hard to pick up under tree cover, let alone in dense urban canyons or inside buildings.

Charles River Ventures of Waltham, MA, is following up on a previous investment in a Mountain View, CA, company called Rosum that has a technology that makes up for GPS’s shortcomings by tapping into a more down-to-earth technology: television broadcasts. Rosum announced today that it has zeroed in on an additional $15 million in venture funding in a financing round involving CRV and fellow existing investors Allegis Capital, Steamboat Ventures, and KTB Ventures. The round also included a new backer, TruePosition, Inc., a subsidiary of Liberty Media.

Mobile devices based on Rosum’s chips can determine their locations by combining the signals from GPS satellites with the synchronization codes embedded in television broadcasts. These codes help Rosum’s system determine the range between the mobile unit and various nearby TV towers, information that can be used to triangulate a device’s position to within a meter or two. Because over-the-air TV signals are designed to be strong enough to reach indoors, the system works even when GPS signals aren’t available.

CRV’s portfolio includes several other companies in the wireless infrastructure and services area, including Jitterbug, M2Z Networks, Staccato Communications, Vanu, and July Systems, iSkoot, and GoTV. Meanwhile, Rosum’s TV-based positioning technology faces competition from another location-finding system based on terrestrial radio signals—the Wi-Fi Positioning System from Boston-based Skyhook Wireless.

Wade Roush is a contributing editor at Xconomy. Follow @wroush

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  • LocationExpert409

    It is critical to obtain accurate and reliable location fixes indoors, especially when it comes to mission-critical safety applications like E-911. It is necessary to locate all 911 calls, including those coming from mobile phones indoors or in big cities. GPS just doesn’t stand up. With Rosum’s technology, combined with technology like that from TruePosition (http://www.trueposition.com/web/guest/u-tdoa), better E-911 call location accuracy can be achieved.