Based On The Under-sampling Of Ultra-wideband Linear Fm Signal Parameter Estimation

Ultra-wide band (UWB) radar is one of the important developing directions of modern radar technology because of its ability in super-resolution and anti-jamming. How to detect the UWB radar signal and estimate the signal parameters under condition of low signal to noise ratio (SNR) is very important. Many new UWB radar signal parameter estimation algorithms based on sub-Nyquist sampling have been deeply and widely studied in this dissertation. Linear Frequency Modulated (LFM) signal is concerned here. The main work of this dissertation can be summarized as follows.1,The Low Probability of Intercept(LPI) of UWB radar is analyzed based on the radar equation and reconnaissance equation. The necessity of making reconnaissance of UWB signal in the circumstance of low or negative SNR is proved.2. Using two different sub-Nyquist sampling frequencies, the UWB signal can be received ambiguously. In addition, based on FFT and remainder algorithm, the modulation rate and initial frequency of sub-sampling UWB LFM signal are estimated unambiguously in negative SNR. It points out that the UWB signal can be reconnoitered efficiently with sub-sampling method.3. One new method that the UWB signal can be received ambiguously has been presented in this dissertation. Furthermore, the sampling LFM signal becomes two sine signals with different frequencies based on two different delay processes. Based on FFT and remainder algorithm, the modulation rate and initial frequency of sub-sampling LFM signal are estimated precisely and unambiguously in negative SNR. Without deteriorating accuracy of estimated parameters, this method needs less hardware.4. Based on ESPRIT algorithm and remainder algorithm, the modulation rate and initial frequency of sub-sampling UWB LFM signal can be estimated unambiguously and precisely in a low SNR background.