Precise point positioning with mixed use of time-differenced and undifferenced carrier phase from multiple GNSS

A multi-GNSS kinematic precise point positioning (PPP) approach that is based on the mixed use of time-differenced and undifferenced carrier phase observations is presented. The approach reduces the number of constant parameters, such as ambiguities and hardware biases, and mitigates quasi-constant systematic errors including residual atmospheric refractions and multipath effects. The effectiveness and efficiency of the proposed approach are validated in some PPP tests of running and vehicle driving. The proposed method requires an accurate initial position. When that is available, up to 71% improvement in positioning accuracy can be achieved compared with traditional PPP. The proposed approach is also computationally efficient, especially for high-rate positioning applications.