Abstracta new methodof using the Navy Navigation Satellite System (NNSS) in marine (i.e. moving‐user) applications has been developed. The technique exploits some little‐known characteristics of the received NNSS doppler signal, and has yielded more than an order of magnitude improvement in position determination accuracy when Earth referenced velocity is poorly known.Use of the technique has greatly expanded the accuracy and utility of the NNSS in marine navigation applications. Tests using at‐sea data have shown that Loran/OMEGA propagation errors can be calibrated to an accuracy of better than 300 feet (rms), irrespective of user motion. NNSS updates for an Inertial Navigation system (INS) can now be provided in both position and velocity, thus greatly increasing INS between‐pass steering performance over that derived from conventional position‐only fixes. The NNSS can now be used by itself as a complete “stand alone” navigation system, providing periodic position, speed, and course information of