| Ultrawideband(UWB) radar is a new type of radar system, and it has high range resolution(HRR) because of broad bandwidth. Thus, UWB radar has extended application such as passive target identification, precise position,target imaging and discrimination. Following the main clue of the UWB technique, We expand our research work enclosing some key techniques in UWB radar, such as target modeling., signal processing,wideband receiver and the application of UWB signal in wireless communication, and so on. The main contribution of this dissertation can be summarized as follows: 1. The UWB radar return model is established and the return signal is simulated. In allusion to UWB radar modeling is not perfect, this subject is investigated. The scattering intensity of different type scatter centers is related to the frequency when target illuminated by UWB signals, impulse response of the target has other function forms except impulse pulse. The UWB radar general model is proposed, and based on it, the simulation results of the early response scattering returns for UWB LFM radar signal are presented. Then, according to the mathmatical description to UWB impulse response in literatures, three kinds of UWB signal modeling are studied, such as LFM,impulse, carrier-free coded waveforms, supposing the target scattering center distribution is given. 2. The UWB radar equation is deduced and UWB signal resolution is analyzed. Radar operation distance is related to radar equation. From narrowband radar equations considering UWB signal has effect on these factors in radar equation, the UWB radar equation is deduced. It is the generalization of narrowband radar equation. Based on the equal energy of the signals in time domain and equal 3dB bandwidth of the main lobe of their spectra,a higher resolution was obtained for the signals that could be directly detected than for those that required a correlation process for detection. This finding has important consequences for the design of systems where the resolution of weak target returns adjacent to strong target returns. 3. Research works have been done on UWB radar signal processing as follows. These works focus on the UWB stepped frequency radar signal. At first , the operating principle,imaging feature of using rectangles LFM signal as subpluse in a stepped frequency radar system is discussed. The key problem of signal processing is analyzed in detail. Then we propose a novel scheme of radar target detection according to the target range profile0 That is extracting scattering centers from range profile firstly, then process with the generalized likelihood ratio test(GLRT). Simulation results indicate that the detector has effective detection performance. Also, thinking about the wavelet transform has favorable localization character in time domain and frequency domain, it is specially apply to process and analysis in wide band signal. the applications in wide band correlation processing and target feature extraction are studied, theoretic analysis and experimental results show that the continuous wavelet transform is an effect approach in ultrawideband radar signal processing. At last the approaches to UWB radar radio frequency interference (RFI) suppression is analyzed, considering the extensive applications of least mean square (LMS )adaptive filter in the field of anti-interference, using it to suppress RFI in UWB radar is studied0 4. The radio front end of UWB radar digital receiver is developed. Developing wideband digital receiver is confronted with...
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