Study On GPS Ionospheric Delay Correction And Analysis Of Disturbance Monitoring

Ionosphere is an important part of space environment near earth. With the rapid development of GPS and other Satellite Navigation System, and precision of navigation and positioning improved gradually, it is a focus for people to influence the electromagnetic signal about ionospheric refraction delay, and also an emphasis to explore ionospheric physical reason and scout ionospheric disturbance. The paper chiefly studies the principle and method of calculating accurately TEC by GPS data, and analyses and compares several different ionospheric models, and also studies the prediction of TEC by GPS data and the method of scouting ionospheric disturbance. The primary content of paper is as follows:1. The paper introduces the basic knowledge of ionospheric study by GPS, including ionospheric basic knowledge, the history and present of ionospheric study, the significance of study and application, and the basic principle of GPS positioning and analysis of errors.2. Secondly, study the principle and method of calculating TEC by GPS data. The paper analyses, inquires and predigests the formula of ionospheric refraction delay, and discusses the influence of GPS positioning about ionospheric refraction, then, on the basis of discussing GPS hardware delay and mapping function, chiefly studies the principle and method of calculating accurately TEC by GPS data, and analyses the kinds of errors among calculating.3. Thirdly, analyze and compare the different ionospheric models. The paper improves the traditional Klobuchar model by real time differential correction of ionospheric parameter, and enhances the corrective precision, then, studies chiefly parametric fitting and precision analysis of VTEC model and spherical harmonic functions model, then, analyses 3D ionospheric model based on computerized tomography technology and WAAS ionospheric grid model in detail, lastly, introduces simply other ionospheric models and methods.4. Lastly, study the method of predicting TEC and scouting ionospheric disturbance by GPS data. On the basis of analyzing ionospheric temporal and spatial relativity, the paper predicts ionospheric TEC by Kalman filter equation of scatter system, then, studies and analyses the instance of ionospheric magnetic storm by calculating accurately TEC on November 20th-24th in 2003, which basically accords with the law of ionospheric magneticstorm, lastly, introduces the method of scouting small ionospheric disturbance--calculatingthe change rate of TEC.