Research On Signal Processing And Imaging Of Ultra-Wideband Radar

Ultra-wideband (UWB) radar is a new type of radar system. It can be widelyused for target recognition, hidden target detection, target imaging and relatedapplications. This dissertation focuses on the two main applications of UWB radar:ground penetrating radar (GPR) and through-the-wall radar (TWR). The focus in thisthesis is to suggest and evaluate signal processing for GPR and imaging technique forTWR. The main contribution of this research can be summarized as follows:(1) In the research of clutter reduction in GPR data, two approaches are proposed.The first is based on exponential moving average. A Multiple Mode Kalman filterapproach is also proposed to clutter suppression and target detection. Clutterestimation, target detection and target-clutter separation are treated as mutuallyprocedure. The posterior probability of each model using Bayes's formula is appliedto detect the target position.(2) In the research of layer picking in GPR data, we make some improvement onthe usual correlation-based layer picking approach. And a novel approach is presentedbased on the Canny edge detection according to the characteristics of reflection signalfrom layers in GPR data.(3) In the research of coherent imaging of TWR, the travel time is calculatedbetween the antenna and the target in closed form based on the refraction model. Amodified back-projection approach is proposed to correct the effects of the wallaccording to the travel time. Then, the cross-range resolution is analyzed based onspace-time beamforming. Finite-Difference Time-Domain (FDTD) is used todemonstrate the efficacy of the approach. Also, the effects of wall thickness and dielectric constant errors on imaging are analyzed qualitatively.(4) In the research of non-coherent imaging of TWR, a one-transmittertwo-receiver non-coherent radar system is presented. Analytical formulations of thetarget 2D localization are given under the condition of both the absence and thepresence of the wall. We also provide the resolution analysis and the supportingFDTD simulation results. And the effects of target range and antenna spacing on thecross-range resolution are analyzed qualitatively.