Commercial Radio Phase Difference of Arrival (PDOA) for GNSS-independent PNT – Carrier Phase

Commercial broadcast frequency modulated (FM) radio provides the opportunity to implement a wide area, potentially nationwide, global navigation satellite system (GNSS)-independent PNT service. FM radio is ubiquitous in the U.S., providing 20 to 50 independent, frequently high-power channels in most locations. Stereo FM radio allows two complementary phase measurements that support PNT: the phase of the FM stereo pilot tone, and the phase of the carrier. The stereo pilot tone, with a long wavelength, provides an easy-to-resolve integer ambiguity but yields a coarse PNT solution, while the carrier phase provides a more challenging to resolve ambiguity but yields the opportunity for a more precise result. This paper reviews the capability of providing PNT data using phase difference of arrival (PDOA) of carrier phase measurements.