| The algorithm of Augmentation Positioning uses the observation of the reference station to provide error correction information to the users in the coverage area and surrounding areas of the reference station,to eliminate or weaken the observation error of user,so as to speed up the convergence speed and improve positioning accuracy.This paper proposed the Augmentation positioning algorithm based on un-difference error correction,which makes the error is independent at reference station and each satellite on the reference station,Compared with the double-difference error correction,un-difference error correction is simple,maximum retain the error characteristics of the observation at station,and the un-difference grid VRS method can better meet the demand of high precision positioning of mass user,specific research content is as follows:(1)The key stage of data processing of Augmentation positioning is introduced.Data preprocessing is the first problem to be faced in positioning,which directly determines the positioning performance.Therefore,the method of Data preprocessing is described.The elimination and weakening of observations error are the key of high-precision positioning.Introduce the source and elimination method of error from three aspects of satellite error,receiver error and signal propagation path.On the basis of data preprocessing and error correction,the position estimation and ambiguity solution of the user are introduced.In order to ensure the reliability of the positioning performance,the quality control of the user is finally introduced.(2)The linear combination of the carrier phase observations separates the ionosphere observations to reflect the variation of the ionosphere,However,the ionospheric delay variation is often affected by the observations noise.In particular,the time interval of ionosphere observations is small,ionospheric delay variation is often overwhelmed by the observations noise,The key to extracting the variation from the ionosphere observations is the weakening of the noise.According to the ionospheric variation is random walk,observation noise is white noise,finally according to their different characteristics with the difference interval,establish a strict mathematical relationship separation of the IPSD,the correlation coefficient of the separated IPSD of the B1 &B2 and B1 & B3 reached above 0.9,indicating the accuracy of the IPSD.IPSD can be used to study the characteristics of the ionosphere,on the other hand through the IPSD application of the ionosphere parameters is more reasonable constraints,improve the performance of positioning.(3)On the basis of the study on the time correlation of ionosphere and IPSD,analyze the influence of the IPSD on the fixed ambiguity performance of the reference station.Compared with the empirical IPSD,the real-time estimated IPSD increased by 25.5% in the fixed time and 7.8%in the ambiguity fixed success rate.The performance is far better than the method of empirical value.On the basis of the fixed ambiguity the reference station,the un-difference error correction at single station is estimated,and the error is interpolated achieve highprecision positioning of user.Finally,through the reference station network generated virtual observations for massive users autonomous positioning,users only need to choose the nearest distance observation of network can realize error correction and high precision positioning.(4)The high precision positioning of user depends on the error correction,However,there are also cases where the reference station cannot provide the error correction,using far single reference station error correction to user,in the case atmospheric delay error cannot get good eliminate,need to increase the atmospheric delay parameters in the positioning parameters.Through the weighted model of atmospheric parameters,the constraints on atmospheric parameters of user stations are realized,and the unified positioning model of different lengths at single reference station is established.at the same the power spectral density of estimated to further improve the user positioning performance.There are 78 figures,24 tables and 138 references. |
