| BeiDou Navigation Satellite System is a global satellite navigation system independently developed by China.Different from others navigation system,Beidou has its own characteristics in constellation composition,signal generation and signal frequency,so it needs to evaluated and analyzed.Beidou relative positioning and speed measurement have been widely used in deformation monitoring,engineering measurement,transportation,aircraft control,ship navigation and vehicle detection.Therefore,it is necessary to study and analyze the relative positioning and speed measurement error and performance of Beidou system.The main work and achievements of this paper are summarized as follows:(1)According to the length of baseline,the different relative positioning model is geiven.This paper analyzes the main error sources and their magnitude in the relative positioning of medium/long baseline,and gives the specific correction methods.Several methods of solution control and check,such as chi square test,F test,normal test and white noise test are given.(2)Based on the zero baseline data of Curtin University,the magnitude of zero baseline residual of different types of satellite observations is calculated,and the correlation between different types and different frequency observations is analyzed.This paper proposes a method to extract the variance of non difference observations from the variance of double difference residual observation,and analyze the error characteristics of GEO,IGSO and MEOsatellites base on the Elevation model.The characteristics of MP and MW observations in Beidou are analyzed.(3)This paper introduces the common ionospheric error correction methods in the ralative positioning of medium/long baselines.Based on the data of different lengths of four baselines in Hong Kong CORS,the ionospheric residuals between stations are calculated and the characteristics are analyzed.Through the residual variance and autocorrelation coefficient,analyzed two ionospheric correction methods advantages and disadvatages.The accuracy of the troposphere calculated by the empirical model of BJFS and URUM stations is analyzed by using the post IGS troposphere data,and the high-precision troposphere error processing method in relative positioning is given.Finally,the influence of ionospheric and tropospheric errors on the positioning accuracy is analyzed.(4)In order to solve the problem of double difference ambiguity mutation caused by the change of reference satellite in the process of double difference positioning,a Kalman filter model for estimating single difference ambiguity parameters is proposed,and its specific implementation formula is given.Through the analusis of the mathematical principle of Ratio,this paper points out the shortcomings of the empirical method to determine the Ratio value,and then puts forward a more rigorous theoretical method to determine the Ratio value through the F-distribution.At last,the method to fix ambiguity of ionospheric free model is given,through MW observation fix wide lane ambiguity and then fix the narrow lane ambiguity.(5)Based on the method of carrier phase difference,a model of measuring the speed of an object by means of the double difference between the satellites and the epoch is put forward.By carrying out the double difference between the epoch and the stars of the carrier phase,the relative distance between the epoch is calculated,so as to obtain the moving speed of the object.Compared with the carrier phase difference method,this method can further eliminate the influence of receiver clock difference in the epoch by observing the difference between the stars.In order to improve the accuracy and stability of the results,the ambiguity parameter is introduced to reduce or eliminate the errors caused by inter epoch cycle slips and observation noises by fixing the double difference ambiguity.There are 70 figures,18 tables,83 references in this thesis. |
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