Robust Surface Navigation
The Robust Surface Navigation (RSN) program seeks to "exploit signals of opportunity to deliver precise location information to the US warfighter in GPS-denied environments," which could theoretically overcome any GPS jamming techniques that the enemy may try. Essentially, Boeing is looking to companies such as ROSUM to figure out how to provide tracking data via terrestrial broadcast signals and augmented broadcast signals instead of GPS.
Source: digital50.comAdded: 14 May 2007