Design Of GNSS Carrier Phase Differential Reference Station

GNSS high-precision positioning technology has many advantages in continuous,realtime,high-precision,all-weather measurement,and high automation in deformation monitoring applications.Deformation monitoring is an important data basis for assessing the operating status of infrastructure facilities and ensuring their safe operation.A dynamic window estimation method is used to implement the carrier phase differential relative positioning algorithm to track the deformation in real time,so that the monitoring station can obtain high-precision positioning coordinates relative to the reference station,and has real-time deformation monitoring capability.The research content aims at the accuracy requirements of high-precision deformation monitoring applications and the performance requirements of real-time tracking.The advantages and disadvantages of GNSS positioning technology are analyzed in current deformation monitoring applications,including the error sources of pseudorange and carrier phase models in high-precision positioning and their correction methods.To make a theoretical analysis of the positioning accuracy of observations,the key techniques of cycle slip detection and ambiguity fixing in differential positioning are discussed and studied in detail.Finally,a set of GNSS high-precision deformation monitoring system is developed based on the differential relative positioning algorithm,and also be tested and analyzed.The main research contents are as follows:1.The GNSS high-precision differential positioning method is studied,and a learning of the difference between static and dynamic positioning models,then a carrier phase double difference observation method fitting method and an improved Doppler cycle slip detection method for different models are proposed.To solve the problem of fixed ambiguity in the differential positioning,a fast solution to the ambiguity of the double difference is completed,based on the LAMBDA algorithm,and the centimeter-level accuracy in the dynamic model and the millimeter-level accuracy in the static model.According to the characteristics of deformation monitoring applications,a dynamic window estimation method is used to design an adaptive Kalman filter algorithm to achieve real-time tracking deformation monitoring in the condition of short baseline applications.The monitoring accuracy is ±2mm in the horizontal direction and ±5mm in the elevation direction.The real-time tracking performance of the monitoring system is shown.2.Developed a dual-mode single-frequency reference station receiver and a differential data forwarding server program to implement network transmission of differential data.Developed a dual-mode single-frequency mobile station receiver.Real-time Kinematic differential positioning technology was used to realize carrier phase differential relative positioning,including vehicle-mounted dynamic rover stations and deformation monitoring static monitoring stations,and conducted motion tests and simulated deformation.The test verified the high-precision positioning performance and deformation monitoring performance of the system.