Research On Wide Area Differential Positioning And Augmentation Techniques For GNSS

Wide-area, real-time and high-precision positioning is a very promising technique in the field of GNSS navigation. Wide area differential positioning technology not only fully meets the performance indicators of real-time and wide-area, but also provides accuracy to better than lm in horizontal and 2m in vertical, which is quite an improvement compared to the stand-alone GNSS accuracy. But lm accuracy level cannot satisfy high precision navigation service. In view of this situation, this paper focus on the theme of positioning to study and analysis two wide area differential positioning technique problems at first, which are, on the one hand, exactly what kind of positioning algorithm is the most applicable to it, on the another hand how to slove the problem of the low precision pseudorange observations.Secondly, this paper also makes some study on the technique of wide area augmentation.Finally, in order to meet the needs of engineering practice, a real-time/afterwards positioning processing software system is designed and implemented. The main research contents of this paper are as follows:(1) The difference between wide area differential positioning and traditional single point positioning is that errors are corrected more thoroughly by the former. The extent of the error corrections will directly determine the user positioning accuracy level and index requirements.The methods of errors correction are analyzed in detail in this paper, and the validity of these methods are verified by experiments.(2) The quality of observations and the data processing method is related to the accuracy of the positioning. In view of this situation, a new single frequency carrier phase smoothing method based on wide area correction information was put forward at first. Secondly, in order to find an optimal algorithm based on wide area differential positioning , this paper study and analysis some parameter estimation method and the performance of these algoritms are demonstrated by experiments.(3) In order to break through the low accuracy of pseudorange observation, carrier-phase measurements are introduced innovative to compensate for the lack of pseudorange measurements in this paper. A single-frequency carrier-phase assisted positioning method is studied and analyzed at first. At the same time, a dual-frequency carrier-phase assisted positioning method is also discussed in this paper.(4) The traditional receiver autonomous integrity monitoring technology based on wide area diffierental systems is discussed in this paper.(5) In order to meet the needs of engineering practice, a real-time/afterwards positioning processing software is designed and implemented. And the wide area differential positioning module is tested. This system not only meets the need of the project, but also provides convenience for following research.