The U.S. armed forces heavily rely on GPS signals for position, navigation, and timing (PNT). Adversaries have demonstrated the ability to interfere with or imitate GPS signals, which could interrupt mission execution, or more dangerously, result in the capture of U.S. resources. The use of signals of opportunity have been investigated as a backup to GPS signals by the academic community and industry. While promising PNT results have demonstrated the potential of using signals of opportunity as a backup to GPS, there are several practical problems that must be solved in order for them to be used reliably by DoD vehicles in real time. Three example problems are: Insufficient number of transmitters for reliable PNT anywhere on or around Earth from any single type of signal of opportunity. Cellular signals are an example of a "type." No commercially available radio frequency front end (RFE) to efficiently sample multiple signal of opportunity types. Unreliable signal of opportunity tracking using traditional signal tracking loops during high vehicle dynamics. StarNav proposes to solve these problems by developing a specially designed device that can simultaneously sample multiple terrestrial and satellite transmitted signals of opportunity and produce PNT observables using deeply coupled signal tracking loops. The deeply coupled tracking loops leverage information from all tracked signal of opportunity channels along with vehicle motion sensor data to prevent loss of signal tracking during high vehicle dynamics.
