Multipath sensitivity and carrier slip tolerance of an integrated Doppler DGPS navigation algorithm

Integrated Doppler techniques are potentially very useful for such critical real-time DGPS (differential Global Positioning System) applications as river and harbor ship steering, aircraft precision approach, and autonomous land vehicle guidance. Offering high measurement precision and reduced sensitivity to multipath, the integrated Doppler observable can be introduced into the user navigation algorithm in several ways. The approach proposed features: a state variable model for code multipath, code-carrier ambiguity, and code-carrier ionospheric delay offset rate; delta-range, integrated Doppler and code pseudorange combined in an optimal manner during new satellite reception; a state variable and covariance model implemented for DGPS reference station extrapolated corrections; and real-time correction of large cycle-slip events. The interaction of filter modules is discussed. A filter covariance model is utilized to assess the impact of multipath strength and correlation time