Location technology firm Rosum Corporation has raised $15 million in a second round of funding. Liberty Media (NSDQ: LINTA) Corporation subsidiary TruePosition joined existing investors Charles River Ventures, Allegis Capital, Steamboat Ventures, KTB Ventures in this round of financing. The Redwood, California-based company will use the funding to expand into mobile TV and femtocell markets, and to find markets outside of the US for its technology. Rosum’s technology uses TV signals to boost GPS, to give consistent coverage both outdoors—where GPS works well—and indoors, where GPS is less reliable (PDF Release).