DGPS Kinematic Carrier Phase Signal Simulation Analysis in the Velocity Domain

S. Ryan, G. Lachapelle and M.E. Cannon

Abstract:	A Differential GPS simulator system (Northern Telecom STR2760 ) is used to generate C/A and P codes and carrier phase signals from an actual GPS constellation to simulate aircraft trajectories with velocities up to 120 m/s, accelerations up to 50 m/s2, and jerk up to 25 m/s3. The simulator system provides truth position, velocity, and acceleration values for the 3-D reference trajectory. Previous results have shown that velocity estimates during constant velocity periods can be very accurately determined using carrier phase measurements. However, during dynamic conditions the carrier phase derived velocities show large errors due to a strong correlation with jerk. For this analysis, data was collected at 10 Hz from an Ashtech G12ä single frequency receiver. The velocities were determined using the raw receiver generated Doppler, central difference carrier phase approximations, and second and third order carrier phase curve fits over various intervals. During constant velocity sections the second order carrier phase curve fit and the first order carrier phase central difference produce identical results. During high dynamics the third order curve fit performed the best. The optimum method for estimating velocities is to adaptively change the velocity computation method based on the dynamics of the receiver.
Published in:	Proceedings of the 10th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1997) September 16 - 19, 1997 Kansas City, MO
Pages:	1035 - 1045
Cite this article:	Ryan, S., Lachapelle, G., Cannon, M.E., "DGPS Kinematic Carrier Phase Signal Simulation Analysis in the Velocity Domain," Proceedings of the 10th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1997), Kansas City, MO, September 1997, pp. 1035-1045.
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