The Algorithm Study On BDS Triple-frequency Baseline Resolution

The development of the triple-frequency technology has brought great unprecedented opportunities and challenges, and it is significant for national development and the public to lucubrate the triple-frequency technology of Beidou navigation and positioning. This paper mainly launches for the study of the theory and method of Beidou triple-frequency data processing, and is mainly related to triple-frequency combination observation, triple-frequency cycle-slips detection, ionospheric triple-frequency correction, and triple-frequency-carrier ambiguity resolution. The main work and results are summarized as follows:1. This paper has studied the theory of triple-frequency combined observation, and carried on the statistical analysis of a series of typical triple-frequency combined observation, according to the different environment, different baseline choice different ionospheric delay effect coefficient and the optimal combination of noise amplification coefficient. And the enumeration method is used to screened and analyze the optimal combination coefficient of the combination of the observed value.2. This paper has preprocessed Beidou measured data cycle slips detection based on triple-frequency pseudo-range phase combination method. Triple-frequency observations can be formed more excellent combination, help to improve the success rate and accuracy of cycle-slips detection. According to Beidou triple-frequency pseudo-range and carrier phase combinations of characteristics, selection criteria given combination of observations, and then validated by using the measured data. The results showed that when the data sampling rate is higher, the epoch between the ionospheric delay variation can be approximated ignored, according to this method to select the optimal pseudo-distance detection and repair phase combination observations all cycle-slips.3. This paper has analyzed the effects of ionospheric delay for navigation and positioning, triple-frequency ionospheric correction coefficient model, meeting the accuracy requirements of high-precision positioning. Ionospheric corrections lead to combination of noise amplification problems were analyzed to derive the triple-frequency ionosphere combination, and the free-ionosphere model will be used if the ambiguity can’t be fixed in short baseline.4. This paper has analyzed the effects of the double difference tropospheric delay error on the relative positioning precision, the results show that the small difference short baseline, estimate the zenith tropospheric delay parameters may reduce the positioning accuracy, instead, in the case of large elevation difference, zenith tropospheric delay parameters could significantly improve the precision of elevation component.5. This paper has used the classic static relative positioning method based on the least square, calculated the result by solving ambiguity as unknowns. Compress the search space of ambiguity and shorten the search time, according to the method of observation equation matrix and the ambiguity float solution by using the LAMBDA method fixed ambiguity, and use ratio values to test the validity of the fuzzy degree of fixed.