Study Of Shore-based Broadband Coherent X-band Radar Wave Information Extraction Technology

Ocean is a natural barrier of nature, it has abundant water, biological andmineral resources. It is an important way of expanding our living space to carryon exploration and exploitation. Our long coastline, vast sea area and rich marineresources make that the study of marine remote sensing technology has a veryimportant significance. X-band radar which can image sea surface is an importantmeans to monitor marine environment currently. Its working frequency is8GHz~12GHz. The advantages such as cheap, convenient, reliable, real-time,high spatial and temporal resolution caused widespread attention of all countries.The paper briefly describes the development and the current researchsituation at home and abroad of the marine remote sensing inversion technologywith X-band radar. Research at home and abroad are based on non-coherentX-band radar, this paper presents the wave parameters inversion method ofX-band coherent and broadband radar. Compared with the non-coherent radar, onthe one hand, it can get the radial wave velocity information by coherentaccumulation, and the formed sea image is a complex sequence, on the otherhand, higher range resolution can be obtained with large bandwidth, thereby canobserve smaller scale waves. Using200MHz large bandwidth in the simulation,range resolution can be accurate to0.75m.The main work of this paper is to study the algorithm of wave inversioncharacteristic parameters with the shore-based X-band coherent and broadbandradar, and put forward coherent integration (two-dimensional FFT) of the radarecho. Weighting and averaging each same range gate wave radial velocity, andsingle-station vector synthesis with the resulted radial velocity, you can get thesea surface current field. Firstly, analyzing the X-band radar imaging theory.Electromagnetic waves emitted by radar arrives the rough sea surface with almostparallel with the sea-level way, due to the fluctuation of ocean wave rolling, andthe similar wavelength of the capillary wave resonant Bragg scattering, and thesea surface longer wavelength gravity wave modulate the capillary wave.Backscatter echo reaches the radar antenna, and generates the sea clutter image.Series of sea clutter continuous image sequences evolved with time to make athree-dimensional discrete Fourier transform spectrum radar images. The use ofthe dispersion relation design spectrum band-pass filter for image filtering,separating the wave energy from the background noise. Integral to the imagespectrum and modulation transfer factor to get them corrected wave directionalspectrum, which can be extracted one-dimensional spectrum and the main wave characteristic parameters. Modeled significant wave height mentioned in SARimages and radar echoes received SNR has a linear relationship to estimate thesignificant wave height waves.Finally, simulating and verificating the proposed X-band broadband andcoherent radar sea state parameters inversion algorithm. Selecting the PMspectrum derived form ITTC two-parameter wave spectrum as well as select atarget spectrum as a function of the direction cosine squared function of thewaves, the waves build stochastic models. Then consider the impact of theshadows and joined the modulated radar image background noise correlationalgorithm processing simulation. The inversion parameters and input parameterswere compared, the results are displayed in the range of allowable error, theinversion algorithm is reasonable and feasible.