Fractional Fourier transform-based unassisted tracking method for Global Navigation Satellite System signal carrier with high dynamics

摘要

This study proposes a novel tracking method for Global Navigation Satellite System (GNSS) signal carrier, based on fractional Fourier transform. This method not only overcomes the limitations caused by the tripartite trade-off between tracking accuracy, loop bandwidth and dynamic stress, but also needs no auxiliary devices such as inertial measurement units (IMUs). Through a time–frequency analysis of high dynamic carrier signal, the authors show that an acceleration estimator can replace the function of IMU, and a high dynamic frequency discriminator can track the carrier Doppler frequency. Since the tracking accuracy (frequency resolution) and loop bandwidth (time resolution) are not affected by dynamics in the authors’ method, the upper bound of dynamic stress is improved significantly. Furthermore, due to the cancellation of IMU calibration and initial alignment, their method improves the rapid reaction capability of vehicles, reduces the possibility of external interference, and simplifies the tracking loop design. Simulation results show that their method has the ability to track GNSS signal under at least 200 g dynamic stress.