Research Of Wave Parameter Inversion By X-Band Marine Radar In Moving Environment

Sea wave is such a complex phenomenon that the research on it makes great significance on ocean engineering construction and development, energy detection, ship transportation,fishing and so on. The monitor of sea wave begins in the early 1950s, and the way to get value by X-band radar image becomes hot in recent twenty years. Now the inversion method of static environment have shown great performance, but there are some new problems in dynamic held up at the same time.On the basis of a studying project, this paper makes analyses and proposes a series of solutions on the inappropriate dispersion relation Band Pass Filter(BPF) and frequency spectrum aliasing.Firstly, spectra energy generates a serious excursion along with the dispersion relation cave because of the enhanced Doppler shift. And this leads almost all the image information in the traditional BPF. In order to solve this problem, this paper designs a new BPF whose time complexity is the same as the old one to make up the inadequacy in traditional BPF. This BPF based on dispersion relation can retain the main energy of wave and suppress noise not only in static but also dynamic environment. The inversion results meet the accuracy requirement and are similar to WAMOS and WAVEX.Secondly, the radar's slow speed brings signal under-sampling, this leads to a frequency spectrum aliasing. By using the marine radar parameters on the sea, this part analyzes the aliasing mechanism, calculates the relationship between wave parameter, the minimum velocity for aliasing and the sampling frequency. The original dispersion relation surface is rebuilt by finding the way of spectra aliasing and using the property of Fourier transformation.The last part designed a simulation experiment on the bases of asymptote regression according to the inaccuracy caused by the uneven between the radar inversed Signal-to-Noise Ratio (SNR) and the effective wave height measured by Wave Monitoring System. This method imitated a ratio of the square of SNR to the wave height under large wave situation.Finally, an inverse transformation was taken on the ratio. The new data show good feasibility,high simulation and accurate distribution on original data proving by the existing data.