Research On Beidou Precision Positioning Based On Wavelet Transform

With the rapid development of modern navigation technology,China has independently built the Beidou satellite navigation system,which can provide maritime,land,and air navigation and positioning and timing services for military and civilian users in China and surrounding areas.The establishment of the Beidou satellite navigation system has quickly promoted China's Development in areas such as security and economic development.In Beidou's high-precision positioning,carrier phase difference is the main positioning method,which mainly depends on the observed value of carrier phase.Cycle slip is a problem often encountered in the process of carrier phase positioning.The occurrence of cycle slip will cause carrier phase Observation changes have greatly reduced the positioning accuracy.Therefore,accurate detection and repair of cycle slips are of great significance to the development of Beidou satellite navigation systems.Aiming at the problem of cycle slips in Beidou,thesis first constructs single and double difference detection quantities under the single and double difference model,applies wavelet transform to the detection of cycle slips,uses wavelet transform to perform three-scale decomposition of single and double difference detection sequences,and extracts high frequency at the same time.Coefficients and low-frequency coefficients.From the singular values ??of high-frequency coefficients,obvious cycle slips can be observed.Then the singular values ??are replaced by Lagrange linear interpolation,and the replaced high-frequency and low-frequency coefficients are reconstructed,and finally the signal is reconstructed By subtracting from the original signal,the cycle slip difference can be obtained,which can be used to repair the cycle slip layer by layer.The simulation results show that this method can detect and repair small cycle slips more effectively.Since each navigation system has certain shortcomings,thesis supplements the research of the BDS\INS integrated navigation system.Most of the inertial measurement units used in this system are MPU6050,and the main components are gyroscopes and accelerometers.Influence of low-frequency noise,in order to improve the accuracy of gyroscope attitude measurement,thesis uses wavelet transform method to fuse gyroscope and accelerometer data to calculate attitude angle.First,the data collected by gyroscope is subjected to 2-layer wavelet decomposition to remove low-frequency components and unstable The signal is reconstructed with the high-frequency components to obtain the filtered data,and then the attitude angle is calculated using the data collected by the accelerometer,and the initial quaternion is continuously iterated.The gravity vector is obtained from the initial quaternion,and then the gravity vector is crossed Calculate the error and use PID control to correct the angle of the gyroscope.Finally,use the Runge-Kuta method to calculate the new quaternion of the corrected and filtered gyroscope data.Use the quaternion to adjust the negative gain,and finally solve Calculating the attitude angle,simulation experiments show that the accuracy of calculating the attitude angle is improved,which can effectively suppress low-frequency noise and further improve the positioning accuracy of the navigation system.