2015 Volume 2015 Pages 156-164
In this paper, we present methods of detecting and correcting Doppler biases which cause positioning errors in Doppler-aided Kalman filter-based GNSS (Global Navigation Satellite System) positioning. It is well known that Doppler frequency shift observables are more precise compared with C/A code pseudorange observables. Doppler shifts are transformed into range-rates and utilized to smooth code pseudoranges. And Doppler shift observables are immune to cycle-slip and continuously available as long as the receiver can track the signals. The precise raw Doppler shift observables can be further exploited for RTK (Real Time Kinematic) positioning to provide robust carrier-phase anomaly detection and correction processes [5, 6]. Therefore Doppler shift observables can be utilized on a priority basis in Doppler-aided Kalman filter-based positioning than C/A code pseudoranges. However unexpected Doppler bias errors cause position errors or route departures in the positioning. If the Doppler shifts include bias errors, they can be detected by monitoring the innovation processes in Kalman filter. And then they can be corrected by the exclusion and estimation methods.