Reliable integer ambiguity resolution requires precise bias estimates for absolute positioning. In this paper, a method for the joint estimation of satellite code, satellite phase, receiver code and receiver phase biases on multiple frequencies is proposed. It uses a Kalman filter and sequential bootstrapping for integer ambiguity resolution. The reliability of ambiguity resolution is improved by an integer decorrelation transformation. The achievable bias accuracies, the benefit of ambiguity resolution and the benefit of measurements on a third frequency is shown for a global network of reference stations. Moreover, a second method is suggested for the joint estimation of code biases and grid ionospheric vertical delays. Code measurements on two frequencies and two linear combinations of time-differenced carrier phase measurements are used in a Kalman filter. The ionospheric delays at the grid points are obtained by a least-squares fitting of the ionospheric slant delays at the surrounding pierce points. The method is validated from both simulated measurements of the EGNOS RIMS stations and from real data.     «

Reliable integer ambiguity resolution requires precise bias estimates for absolute positioning. In this paper, a method for the joint estimation of satellite code, satellite phase, receiver code and receiver phase biases on multiple frequencies is proposed. It uses a Kalman filter and sequential bootstrapping for integer ambiguity resolution. The reliability of ambiguity resolution is improved by an integer decorrelation transformation. The achievable bias accuracies, the benefit of ambiguity r...     »