Research And Implementation Of Sea Clutter Algorithm Based On FPGA

The sea clutter that is widely existed in nature seriously interferes with the radar's ability to detect targets.Therefore,the research on the characteristics of sea clutter and its theoretical modeling have been the focus of researchers at home and abroad.Studying its distribution characteristics and mastering its distribution law not only helps to improve the detection and tracking of radar targets,but also helps to promote the development of clutter suppression technology.The accurate modeling of sea clutter can provide a more realistic clutter environment model for designing radar system simulation,and can also provide a strong reference for the design of clutter simulator.This paper mainly focuses on the modeling and simulation of sea clutter,and designs and implements an algorithm which can effectively simulate sea clutter through the platform built by FPGA.It mainly includes the following aspects:1.It is briefly described that the main theoretical model of the current study of sea clutter,the statistical model.In this part,the empirical model of backscattering commonly used in sea clutter and the significance of scattering coefficient are first described.Then the two characteristics of sea clutter statistical model are expounded: amplitude distribution characteristics and power spectrum characteristics;Finally,two methods commonly used in simulating sea clutter are introduced: Zero-Memory Nonlinear Transformation method and Spherical Invariant Stochastic process method,and the advantages and disadvantages of these two methods are compared.2.The software and hardware platforms used in the implementation of sea clutter simulation are introduced.The contents are as follows: firstly,the structure characteristics of FPGA are introduced.Then,the simulation flow based on FPGA platform design is described.Finally,the hardware language environment--Verilog HDL used in this paper is introduced,the hardware development platform selects the Cyclone series provided by Altera manufacturers,the chip model is P4CE115729C7,and the software development platform is Quartus II and Modelsim.3.The specific method of generating sea clutter is detailed.Firstly,the design idea of sea clutter based on FPGA is introduced.Secondly,the core algorithm for generating sea clutter on FPGA is analyzed: CORDIC algorithm,and the working principle and hardware implementation method of CORDIC algorithm are analyzed.The sin/cos function is taken as an example to illustrate the flow of CORDIC algorithm.Then,the design idea of generating uniform distributed random numbers by m-sequence generator and the process of obtaining Gaussian distributed random numbers by Box-Muller transform method are introduced.Then,the design method of FIR filter in the field of digital signal processing is introduced,and a simplified hardware realization structure of FIR filter is designed,and the Gaussian color noise is obtained by this filter.Finally,the generation of Rayleigh distributed clutter is realized by the zero-memory nonlinear transformation method,and the simulation results are analyzed,which shows the correctness of the model.4.The research is mainly carried out around K distributed sea clutter.Firstly,the amplitude distribution characteristics and spatiotemporal correlation characteristics of the composite K distributed sea clutter are analyzed according to the scattering mechanism.Then,the parameter estimation method is discussed in detail when there is no measurement data and the composite K distribution needs to be used to carry out the statistical simulation of sea clutter.Finally,a simulation of the sea clutter of one-dimensional correlation coherent K distributed sea clutter and spatiotemporal two-dimensional correlation K distribution is presented based on the spherical invariant stochastic process method.Then,the data of the simulation are analyzed statistically,and the feasibility of the method is proved.