【作者】 赵学云；

【导师】 刘峥；

【作者基本信息】 西安电子科技大学 ， 信号与信息处理， 2006， 硕士

【摘要】 本论文研究了编队目标多普勒频率的变化特征和基于此的架次识别方法。首先,介绍了低分辨雷达架次识别方法研究的发展状况,对常见的架次识别方法作了归纳总结,其中主要详细说明了基于时频分析和波形特征提取的架次识别方法。其次,根据编队目标的间距较小、飞行速度近似相同等特点,分析了编队飞行目标回波多普勒频率的变化情况,得出了结论：低分辨雷达编队目标回波可以用线性调频信号描述。提出了两种架次识别方法：第一种是基于Radon-WVD变换(Radon-Wigner-Vill transform)的编队目标架次识别方法,在时频域对编队目标的整体特性(调频率)进行快速准确的估计,该方法充分利用了Radon变换的积累特性使得Radon-WVD变换法相对WVD法有更好的抗噪声性能,且不受交叉项的影响；第二种是基于频率域细化的编队目标架次识别方法,通过对CZT(chirp Z-transform)和Zoom-FFT两种频域细化方法的分析和比较,提出CZT法可以在更短的时间内较快速、准确地对毫米波雷达编队目标的架次进行识别。最后,引入了微多普勒效应的有关概念,给出了目标部分结构相对目标体作三维转动和振动时微多普勒频率的数学模型,为通过微多普勒频率变化情况对多目标进行分辨和识别提供了依据。更多还原

【Abstract】 The work of this dissertation is focused on research of targets number detection. Firstly this dissertation introduces methods of target number detection radars in common use and classifies them into several categories. Secondly due to the short distance between airplanes which fly in a group, the ordinary radar can’t distinguish them in both distance and azimuth. The variation of Doppler frequency of the group flying targets is analyzed in this paper. It is found that they can be modeled as linear frequency modulated (LFM) signal. The time-frequency analyzing methods are proposed to analyze the signal. The possibility of distinguishing targets in time-frequency domain is investigated. The author provides two methods to solve the problem. The fist method is target number detection based on Radon-WVD transform (Radon-Wigner-Ville Distribution). Through this way we can make a fast estimation of the entire feature in the time-frequency domain. The cross-terms of WVD have no influence on the result of the estimation. The method performs well under both higher SNR and lower SNR. The other method is target number detection based on Zoom spectrum. Through analysis on the performances of CZT(chirp Z-transform) and Zoom-FFT, it is proved that the CZT method has much more better capability. Finally the micro-Doppler effect of dynamic targets is introduced. Two mathematical models of micro-Doppler effect, which are induced by mechanical vibration or rotation of a target are developed.更多还原