Abstract:We discuss the relationship between the PDOP value of satellite constellation and satellite number and analyze the magnitudes of the residual errors of pseudo-range and carrier phase observations value. We propose a classification factor robust adaptive filtering method. This method is applied for precise point positioning and the equivalent replacement is based on observation of the different values. At the same time, the adaptive factor is set up according to the characteristics of different parameters and calculated by the prediction residual. Experiments show that this method can not only detect and control the influence of the abnormal values, but can also improve the accuracy and reliability of PPP.