Abstract: The paper discusses the way of improving positioning accuracy by eliminating the systematic errors in the navigation data. Based on the Kalman filter of window fitting systematic errors, the method and process for determining the window length are discussed. The optimized idea was introduced, which was made to be more suitable for coding by the pattern－search methods for determining window length. The Pattern－search moving windows method has wider applicability in fitting systematical errors.

Key words: filtering, fitting, coding, searching, systematic error