Research On OFDM Radar For Target Detection Methods In Ground Clutter

The problem of targets detection in ground clutter is the difficulty in the field of radars. Moreover, the target detection performance of radar is seriously influenced by the multipath and the standoff jamming in low-altitude battlefield. As the system of radar the OFDM(Orthogonal Frequency Division Multiplexing) radar has the advantages of multifrequency, the orthogonality between subcarriers, the diversity of encoding and the waveform design. However, it should be studied to decide wether the performance of OFDM radar in targets detection, recognition and tracking under different circumstance is good, especially the target detection methods in ground clutter. As a result, this article mainly discusses the detection methods based on the likelihood ratio and space time filter.The article is divided into four parts:The first part is mainly about the background and the significance of this research. It is mainly discussed in two sides: the research status of the techniques adopted by radar when detecting targets in clutter and the key techniques of OFDM radar.The second part emphasizes the amplitude statistical model and the spatial property of ground clutter. The reflectivity models in different positions and echo model are built and the clutter signals of different distributions are generated. Then the echo signal model based on the scattering cells is introduced and simulated.The third part mainly studies the the detection methods of OFDM radar based on the likelihood ratio. Firstly, the advantages and disadvantages of OFDM radar signal are analyzed. Then the test theory is formed and the waveform design is used to improve the target detection performance in ground clutter. At last the PAPR(Peak-to-Average Power Ratio) constrain is considered when designing the waveform of OFDM signals.The fourth part mainly studies the detection methods of OFDM radar based on the space time filter. Firstly, the performance of SLC(Sidelobe Canceller) in ground clutter is analyzed, due to ground clutter, the optimum weighs calculated by SLC cannot be applied which affects the detection performance. Then based on the difference of space and time between the clutter and jamming, the model of OFDM STAP(Space Time Adaptive Processing) is formed in the background of airborne radar. The multi-objectve optimized waveform design is proposed which can not only improve the performance of OFDM STAP but also maintain the good property of WAF(Wideband Ambiguity Function) of OFDM signals.The detection methods and the waveform design methods discussed in the article enrich the target detection theory of OFDM radar in ground clutter.