| GNSS-R（Global Navigation Satellite System-Reflection）is a new remote sensing technology,which has the advantages of passive detection,all-weather,no transmitter,light weight,low power consumption,low cost,etc.,and has been widely used in sea surface altimetry,sea surface wind field retrieval and other fields.Accurate measurement of marine gravity field is one of the main contents of marine surveying and mapping,and inversion of marine gravity field based on satellite reflection signal data is a new research direction in the field of marine remote sensing.In this paper,the gravity anomaly inversion based on the vertical deviation method of GNSS satellite reflection signal,the construction of GNSS-R sea surface height measurement model and the solution of GNSS-R water surface mirror reflection point position are studied.The main contents and achievements are as follows:（1）Several gravity anomaly inversion methods are analyzed,and the calculation method of vertical deviation is studied.Firstly,Stokes inverse algorithm for gravity anomaly inversion based on land surface height information,inverse Hotine formula method for gravity anomaly inversion based on gravity disturbance and inverse vertical deviation algorithm for gravity anomaly inversion based on inverse Vening-Meinesz formula are compared and analyzed.Secondly,the calculation of vertical deviation based on satellite altimetry data along the track is studied,and the influence of inner band effect and the choice of integral radius on gravity anomaly inversion accuracy is analyzed.The simulation results show that the calculation results of gravity anomaly are more accurate when the integral radius is between 30 ′ and 70 ′.（2）The sea surface height measurement model based on GNSS-R basic height measurement principle is constructed.Firstly,based on the characteristics of GNSS reflected signal and the basic model of height measurement,the code delay method,carrier phase method and carrier frequency method are analyzed and the advantages and disadvantages of several methods are summarized Secondly,combining the characteristics of simple model construction of code delay method and high precision of carrier phase method,a GNSS reflection signal height measurement method with phase smoothing C/A code pseudorange is proposed,which can effectively solve the problems of low precision of code delay method and integer ambiguity of carrier phase method.Finally,the height measurement model is constructed and verified by experimental simulation.The results show that the phase smoothing C/A code pseudorange method can effectively improve the accuracy of height measurement.（3）The location estimation algorithm of mirror reflection point based on GNSS-R geometric relation is studied.Firstly,based on the analysis of the current algorithm for estimating specular reflection points,it is classified into geometric relation method and mathematical model method according to the algorithm idea.Secondly,based on the idea of mathematical model,an algorithm for solving the position of mirror reflection point by sequence approximation is proposed Finally,the angle dichotomy,advance and retreat method and sequence approximation method are simulated and analyzed by MATLAB,and the number of iterations,operation time and absolute value of reflection angle difference of incident angle are taken as evaluation indexes of algorithms.Simulation results show that the number of iterations of sequence approximation method is better than angle dichotomy method,and the number of iterations is similar to that of advance and retreat method,but the operation time is much better than that of advance and retreat method,and the sequence approximation method is more efficient.（4）Verification experiments such as the accuracy of shore-based lake surface altimetry model,the solution of mirror reflection point of water surface and gravity anomaly inversion are carried out.The lake height is calculated by using the code delay method and the model of phase-smoothed C/A code pseudorange method proposed in this paper.The experimental results show that the error of code delay method is 3.31%,the error of phase-smoothed C/A code pseudorange method is 1.79%,the standard deviation of code delay method is 0.6230,and the standard deviation of phase-smoothed C/A code pseudorange method is 0.1911.The vertical deviation is calculated by combining the lake surface height data and the position information of specular reflection points,in which the average error of the east unitary circle component ηis 1.626″,and the average error of the north meridian circle component ξ is 1.032″.The gravity anomaly is inverted by the removal-recovery method,and the average error of the calculation result is 3.34 m Gal. |
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