Research On Tropospheric Delay Correction Model

In the process of signal propagation,troposphere plays a role in warping the path of it.So,the results of measuring distance differ.It leads to tropospheric delay,which worsen the positional accuracy of GPS.Therefore,the tropospheric delay correction is always the focus of the research of GPS.In the field of GPS application,it is of important value that understanding the reason and influence factor of the tropospheric delay,mastering the change rule of GPS,scientifically modeling and matching the change role,and improving the positional accuracy of GPS.(1)The basic atmosphere theory of troposphere was introduced in this article,the classic Hopfield model of tropospheric delay and the theory of neural network BP model.(2)Based on the different months of 2010 data of tropospheric delay(note:data extracted from aero logical sounding balloon observation will be treated as true-value),estimate the accuracy of Hopfield model,and comprehensively analyze the Hopfield model based on various meteorological parameter and elevation.The accuracy of Hopfield Model is perfect,but deviation is caused by elevation and season factors.Therefore,it should be combined with reality in the process of application.SPSS software has been used to do regression analysis and correlation analysis according to the parameters of atmosphere and other related parameters.The conclusion is that the relevance of 2 parameters(atmospheric pressure and elevation)and tropospheric delay value is significant,while the relevance of other parameter is relatively low.(3)Combined with the above analysis results,7 kinds of neural network BP models are built,including model 6×P×1,model 5×P× 1,model 4×P× 1(2 kinds and model 3×P×1(3 kinds).In these models,1 parameter is delayed in all their output layers.After the comparison of analysis,the effect of model 3b×P×lis optimum.(4)Combined Hopfield model with BP neural network,two composite patterns were built.After verification of these 2 models,it has been found that the second model is better,which was named as "HF-BP" model.Compared with Hopfield model,the accuracy of model "HF-BP" can improve 40%.In final,this article made analysis and conclusion of the timeliness of "HF-BP" model.