GPS Signal Tracking on a Multi-antenna Mounted Spinning Vehicle by Compensating for the Spin Effects

To receive GPS satellite signals continuously on a spinning vehicle, an omnidirectional wraparound antenna or multiple patch antennas are needed. If multiple patch antennas are used, as spin effects, Doppler frequency is induced by the rotation of the antennas, and carrier phase changes abruptly when the receiving antennas are changed by the antenna's beamwidth. Because the spin effects make it difficult for a conventional GPS receiver to track the signals, this paper proposes an algorithm to compensate for the spin effects on a GPS receiver. First, roll angles are estimated by a GPS roll-angle determination algorithm and then the Doppler frequency and the magnitude of the phase discontinuity are calculated based on the estimated roll angles, which are used in the phase locked loop of the receiver to compensate for the spin effects. Finally, the performance of the proposed algorithm is validated by computer simulations.