Joint Sea Surface Height And Tide Estimation Based On Airborne GNSS-R,Coastal GNSS-R Wavelet Denoising And Sinusoidal Fitting

When the Global Navigation Satellite System(GNSS)signals pass the sea surface,it will have the effects of reflection and scattering.When these reflected and scattered signals enter the receiver,the multipath effects will be generated,which leads to measurement errors.Therefore,these signals need to be suppressed in navigation positioning measurements.With the development of GNSS system and technology promotion,the sea surface height(SSH)can be measured by using these reflected or scattered signal.This new remote sensing method called GNSS-R(GNSS Reflectometry)altimetry.As a new sea surface measurement technology,it can provide long-term stability and high spatio-temporal resolution signal,which can make up for the shortcomings of traditional sea surface altimeters,such as high cost of technology,small range of altimetry and lack of systematicness and completeness.This new measurement technology,which has become one of the hot topics in the field of GNSS,are expected to be solved Meso-scale SSH measurement problem.In this paper,the existing theory and method of GNSS-R altimetry are introduced.On this basis,theoretical derivation and experimental analysis are conducted.The main contents and innovation of this paper are as follows:1.Summarizes the existing GNSS-R altimetry geometric model,deduces its altimetry formula,discusses how to extract the relative direct signal delay of the reflected signal,and uses the peak method and the maximum rate of change method to extract the code delay by using the GOLD-RTR data in an airborne altimetry experiment.2.Introduces the principle of SSH inversion by shore-based GNSS-R,and uses the measured GPS and GLONASS data to verify the method.The results show that the inversion of SSH by GPS-R and GLONASS-R is feasible.3.Using the SNR data of three satellite navigation systems of BDS,GPS and GLONASS to invert the SSH,the feasibility and effectiveness of multi-mode GNSS-R in monitoring the SSH changes are verified.4.In order to improve the accuracy of multi-mode GNSS-R inversion,the wavelet denoising and sinusoidal fitting of the multi-mode GNSS-R inversion were performed.The results show that the correlation coefficient of wavelet transform and sinusoidal curve fitting are improved 14.4% and 16.8%,while the RMSE is reduced by 42.7% and 57.2% respectively.