| The development trend of modern radar is high resolution, ultra-wideband, Intelligence,multifunction, etc. Ultra-wideband radar is widely used as a new type of radar system. The existing A/D converter cannot sample the UWB radar signal directly. The pulse compression of ultra-wideband radar signal is difficult to realize. The problem can be solved by the band-splitting technology. However, the segmentation process inevitably produces aliasing,amplitude and phase distortion because of the non-ideal channel dropping filter. These distortions will cause big errors between sub-band pulse compression result and direct pulse compression result.In this paper, improvement of UWB radar signal pulse compression performance is studied. The main achievement of this dissertation can be summarized as follows:1. The paper analyzes several sampling signal theory involved in the process of designing channel dropping filter. The error sources of two channels and M channels channel dropping filter and the design of UWB radar signal sampling system are discussed.2. The integrated pulse compression by band-splitting technology is studied. The paper chooses the classical Butterworth and Chebyshev filter to split, and compares results of ideal channel dropping filter and classical analog channel dropping filter. The formula of sub-band pulse compression is derived. The pulse compression results of three kinds of channel dropping filters are compared and the effects on sub-band pulse compression result of channel dropping filters are discussed.3. The paper analyzes relationship reconstruction filter, analysis filter and prototype filter. The perfect reconstruction condition of quadrature mirror filter(QMF) banks is given.4. For the design of the prototype filter, window function method, variable dimension constraint method and the optimization method of optimal frequency domain criterion based on wavelet are studied. For the design of multi-channel QMF banks, the design method based on linear iteration is applied. The simulation analysis shows that QMF banks designed has good characteristics of the reconstructed signal.5. The method that digital QMF is converted to analog channel dropping filters is researched. The sub-band pulse compression results and comprehensive pulse compression results using QMF designed are simulated and analyzed.The simulation results show that channel dropping filters designed in the paper can reduce aliasing distortion, which improves the pulse compression performance of UWB radar signal. |
PDF Full Text Request