Target Detection In The Background Of Sea Clutter For High Resolution Radar

Target detection in the background of sea clutter is an important issue in the field of radar signal processing.In particular,with the improvement of radar resolution and the reduction of the intersection angle between radar beam and the horizontal plane,the distribution of sea clutter tends to be complicated and the sea peak phenomenon becomes more obvious.Traditional detection algorithms become ineffective.This thesis mainly introduces relevant knowledge of target detection in high resolution radar,suggests several improvement measures and introduces their engineering implementations based on the measured data.This thesis first introduces the fundamentals of detection and several basic constant false alarm rate(CFAR)detection algorithms.Since different CFAR methods are applicable in different clutter environments,the adaptive CFAR algorithm which determines current clutter environment and automatically selects CFAR detector is then introduced.This thesis introduces an adaptive CFAR algorithm named variability indication algorithm.Meanwhile,for the problem that the algorithm is easy to miss the target at the edge of the clutter,several improvements have been made in this thesis including adding a step of judging clutter edges.Matlab simulation experiments have proved that the modified algorithm can improve the detection performance at the clutter edges.Then,combined with the measured data of IPIX radar and XXX radar,this paper analyzes the amplitude characteristics,Doppler frequency characteristics and the correlation of sea clutter echo.Meanwhile,this thesis introduces the rayleigh distribution,lognormal distribution,Weibull distribution and K-distribution combined with the amplitude statistical characteristics of sea clutter echoes.Among them,the K-distribution is a frequently-used mathematical model for sea clutter.In addition,the sea spike phenomenon is a sign of sea clutter shifting from a steady state to an unsteady state.For radars,it tends to be a moving or stationary target which is randomly distributed in the range and Doppler domains.The suppression of sea spikes is always a problem.In this paper,based on the radar measured data,and by analyzing the amplitude characteristics of the sea spikes,a range domain sea-peak suppression algorithm is presented which is relatively simple and practical for engineering implementation.Processing of the measured data proves that the algorithm has a good suppression effect on the sea-peaks which is small in range domain.Finally,combined with a certain radar project,this thesis introduces the specific flow and steps of FPGA hardware implementation of several radar target detection algorithms.By pipelining and registering,CFAR thresholds are computed while ensuring the timing stability.Several CFAR methods similar in implementations are merged into a single module to save computing resources and storage resources of the hardware platform.Finally,FPGA sub-modules that the author is responsible for are successively tested both in single-board test and in system joint test.And this project has successfully passed the inspection.This thesis introduces theoretical knowledge of target detection in the background of sea clutter and detailed steps of FPGA hardware implementation from a perspective of engineering implementation and in combination with radar measured data.We adopt an easy-to-implement radar target detection process.After verifying by an actual radar project,sea clutter and sea spikes can be well suppressed,and over-the-sea targets can be detected more accurately.