Research On Signal Processing Techniques Of Coastal Inverse Synthetic Aperture Radar

Coastal Inverse Synthetic Aperture Radar (ISAR) is a new general coastal defense system. The signal processing techniques of Coastal ISAR include two aspects, one is for the detection mode, and the other is for image mode. The research is based on the detection mode, and provides an entire signal processing scheme for engineering implementation. The accurate information of range, velocity and azimuth is important for the image mode to catch the target quickly.The azimuth estimation, due to large computation cost and low accuracy of traditional angel measurement in mechanical scanning radar, a new application of monopulse techniques is proposed. First of all, this paper introduces the principle of monopulse and analyzes the difference in accuracy between monopulse and the traditional methods. Based on that, engineering implementation is then discussed. Finally, the obtained experimental data from detection mode of ISAR is processed by this method, and results demonstrate effectiveness of the proposed method.The target detection first do pulse compression and the pulse coherent processing to get the Range-Doppler image, and then use the const false alarm ratio (CFAR) detection algorithm to get the detailed information of range and velocity. Order statistic (OS-) CFAR is a widely used and adapts detection method for engineering application, and has some advantages over cell averaging (CA-) CFAR, especially in cases where multi-targets is present or reference window is crossing clutter edges. The finally processing result of the experimental data demonstrates the effectiveness of the method, and its feasibility for engineering implementation.Another important task of the detection mode is to track the targets it detects. The coastal ISAR adopts the Mechanical Scanning antenna, which is a track-while-scan (TWS) system. Except the traditional problems, the TWS system also has some other problems, e.g. the time series to process the different priority tracks etc. For the above problems, a partly overlapped section is proposed to associate different priority track. At last a feasibility multi-target track processing flow is proposed, which has a practical reference to establish the engineering track scheme.