Soldiers may no longer need to rely on satellite navigation to pinpoint themselves or targets, if a new US military research project succeeds. New Scientist reports.

"The Robust Surface Navigation programme, funded by the US government's Defense Advanced Research Projects Agency (DARPA), aims to extract accurate positioning information from "signals of opportunity". These may include television and cellphone transmissions, if satellite signals are unavailable.

Global Positioning System (GPS) receivers pinpoint their location by measuring precisely how long signals from several satellites take to reach them. But these signals can be difficult to receive in built-up urban areas, or inside buildings, and can also be jammed by an enemy.

To overcome this problem, the Robust Surface Navigation project is intended to replace missing GPS information by using other incidental signals to calculate location. "

Source