Self-Differential Doppler Positioning With Iridium NEXT LEO Satellites

Low Earth orbit (LEO) satellites rely less on ground reference stations and can estimate the receiver’s approximate position through continuous Doppler measurements, even when global navigation satellite system (GNSS) signals are weak or unavailable. Since LEO satellite signals are primarily designed for communication rather than navigation, they do not provide accurate satellite orbit information or error correction parameters. To address these issues, we propose a self-differential Doppler positioning (SDDP) method. This method extracts pseudorange rates and pseudorange variations from consecutive Doppler measurements collected by a single receiver over a period of time. By constructing a pseudorange–Doppler joint measurement model and aggregating potential errors into a unified error term, SDDP achieves approximate error compensation without relying on external infrastructure such as reference stations, thereby producing a differential-like positioning effect. To validate SDDP, we analyze the impact of potential measurement errors on positioning performance. Real signals from Iridium NEXT satellites are collected in three scenarios with varying levels of obstruction, and Iridium Satellite Time and Location (STL) information is extracted to validate the SDDP method. Compared with the undifferenced Doppler positioning method, SDDP achieves at least a 50% improvement in positioning accuracy. Furthermore, with the pseudorange–Doppler joint measurement, its accuracy can be improved to within 13 m.