Research On Establishment And Algorithm Of Regional Ionospheric Delay Correction Model Under Network RTK

Ionospheric delay has always been one of the main errors affecting the positioning accuracy of network RTK.In order to reduce the influence of ionospheric delay on the positioning accuracy of network RTK,it is necessary to establish a suitable regional ionospheric delay correction model and develop an improved test.The algorithm for correcting the accuracy of the ionospheric delay error of the station.In this paper,the regional ionospheric delay correction model under the network RTK is constructed by using the double-difference ionospheric delay data of the CORS stations in the central United States.Through experiments,it is proved that for the network RTK region,the interpolation model and the BP neural network model can achieve the precision required for ionospheric research and application.The main work and conclusions of this paper are as follows:(1)Combining the relative positioning difference model,the double-difference observation model is derived,and the double-difference ionospheric delay formula is derived.The variation of the double-difference ionospheric delay at different distances is demonstrated by experiments.Experiments show that the error of the double-difference ionospheric delay between stations is better than the error of the double-difference ionospheric delay between stations under long distances of 3?5cm.Under long-distance conditions,the double-difference ionospheric delay error between stations is above 0.03m,and the error of the double-difference ionosphere between individual stations is as high as 0.26m.In general,as the horizontal distance between stations increases and the satellite elevation angle decreases,the double-difference ionospheric delay between stations will gradually increase.(2)Taking LIM model and DIM model as the research objectives,the two model formulas are deduced in turn,and applied to the study of regional ionospheric delay correction model under network RTK.The experimental results show that the interpolation precision of the LIM model is relatively high,and the interpolation error is mostly within 0.05m.The accuracy of the DIM model is relatively poor,and the interpolation error is mostly greater than 0.05m.In general,for the long-distance network RTK,the interpolation precision of the LIM model and the DIM model is up to the centimeter level,but the interpolation precision of the DIM model is not as high as the interpolation precision of the LIM model.(3)Combined with the advantages of BP neural network model,the BP neural network model is applied to the study of regional ionospheric delay correction model under network RTK.Experiments show that for the network RTK region,the BP neural network model estimates that the delay difference of the double-difference ionosphere between stations is up to the centimeter level.Compared with the LIM model and the DIM model,the interpolation accuracy of the BP neural network model for the double-difference ionospheric delay is better than that of the DIM model from 0.01 to 0.02 m,which is slightly better than the LIM model,and is also applicable to the regional ionospheric delay modeling.Figure[47]table[4]reference[81]...