Beidou Tri-frequency Data Preprocessing And Whole-circumference Ambiguity Resolution Research

With the development of global satellite navigation system,China self-developed system-BeiDou Navigation Satellite System(BDS)developing rapid,but faced with the compete press of developing navigation system of other countries at the same time,BDS requirements on the performance and accuracy of the system is more and more high.As the core technology of BDS positioning,data preprocessing and integer ambiguity resolution need to be improved immediately.This paper makes a deep research on these problems,analyzes the details of positioning principle of BeiDou satellite navigation system.According to the characteristics of BeiDou signal,the basic view measurement and its error characteristics are introduced.Aiming at the problems in the positioning process of BDS,analysis and put forward the feasible improvement program,including the detect and repair cycle slips and the observation matrix of ill posed problems in calculating ambiguity.According to the problems of cycle slip hard to detect,analysis of the main reasons is the shorter wavelength band and various noise.Then in view of this situation,choose appropriate combination coefficients to construct the observation value of the linear combination of amplification wavelength and eliminate the ionospheric delay and observation noise,and introduces EEMD method to decompose the combined observation,extract the energy value as the characteristic vector,and send to the BP neural network as training samples to train the network,and then use the network to identify the combined observation whether slips or not,paper choose combination coefficient of two groups,and choose the optimal coefficient combination according to the cycle slip detection results.Finally,the BP neural network is used to repair the cycle slip.In view of the observation matrix ill happens in short observation time in calculating ambiguity,this paper introduces the TIKHONOV regularization principle to regular the observation matrix,weakening the pathological of measurement matrix,then the float ambiguities search using LAMBDA method,finally fixed ambiguity value.In this paper,we discuss the selection of the regularization coefficient when the TIKHONOV regularization-LAMBDA method is used to solve the integer ambiguity.The range of the optimal regularization coefficient is determined by using the results of multiple sets of data.Finally,experimental verify the effectiveness of the work done in this paper to detect and repair cycle slips and integer ambiguity solution,and the results were summarized and prospected.