Research On The Method Of Partial Ambiguity Resolution Based On BDS/GPS Combined Positioning

The satellite navigation system field has formed a trend of common development of BDS,GPS,GLONASS,Galileo and other satellite navigation systems,The compatible coexistence of these systems makes Multi-GNSS combined positioning possible.Carrier phase measurement is an effective method for Multi-GNSS combination to achieve high-precision positioning,the correct fixation of integer ambiguity is the key to achieve high-precision measurement of the carrier phase,Although the combined positioning of Multi-GNSS can improve the accuracy of the float ambiguity solution,it also leads to a time-consuming solution and increases the risk of all ambiguities being successfully fixed.Therefore,based on the comprehensive comparison and analysis of the combined positioning of Multi-GNSS,this paper proposes a new partial ambiguity resolution method based on the ambiguity dilution of precision(ADOP)theory,and combines the relative positioning theory and algorithm to design a real-time visualized location service software,and passes the actual measurement dynamic data verifies the correctness,feasibility and stability of the software.The main research contents and results of this paper are as follows:(1)Research on combined positioning of Multi-GNSS.This paper introduces a Multi-GNSS single-frequency single-epoch positioning mathematical model based on pseudorange and carrier phase,and based on the measured GNSS data in different regions,the positioning effects of BDS,GPS and BDS/GPS are comprehensively compared and analyzed.At the same time,the influence of BDS high-elevation-angle satellites on the integer ambiguity float resolution in the BDS/GPS combined system is studied,and the results show that in the positioning of the BDS/GPS combined system,the high-elevation-angle satellites are beneficial to improve the accuracy of ambiguity float resolution and the reliability of ambiguity fixation.(2)Research on partial ambiguity resolution.This paper introduces the theory of ADOP,analyzes the properties of the ADOP,and introduces the closed-form expressions of ADOP under various positioning models.Based on the theory of ADOP,a partial ambiguity resolution method of BDS assisted GPS solution is proposed.This method uses ADOP as the threshold factor,and gradually adds BDS satellites to GPS,and selects the corresponding subset of these satellites from the float ambiguity solution of the full ambiguity solution Through experiments under different environments,the results of this method and the full ambiguity resolution method and the partial ambiguity resolution method based on variance sorting method are compared and analyzed.The results show that the new method has the highest calculation efficiency among these methods,the Ratio value is better than the full ambiguity solution,the PDOP value,ADOP value,and positioning accuracy are better than the variance sorting method,the IB success rate(P_s,IB)and the experience success rate(P_s,E)are approximately equal to the full ambiguity solution.(3)Research on software design and implementation.Based on the aforementioned research content,this paper designs and develops a GNSS Real-time Visual Location Service Software prototype,and simulates real-time visual display through measured GNSS dynamic data.The results show that the software can visualize the position,speed and other information of the moving carrier in real time,and can monitor their speed in real time.If the speed is exceeded,the correct warning prompt can be obtained on the Google Earth map,which verifies the feasibility,reliability and stability of the software.There are 72 figures,18 tables,and 116 references in this paper.