【作者】 郭靖；

【导师】 张宁；

【作者基本信息】 哈尔滨工业大学 ， 信息与通信工程， 2010， 硕士

【摘要】 脉冲压缩技术在现代雷达中应用广泛,它有效地解决了雷达距离分辨力与平均功率之间的矛盾。相位编码信号是常用的脉压信号,随着数字技术和DSP技术的发展,人们开始寻求具有更大的脉冲压缩比的信号,使多相编码信号得到了人们的广泛关注。然而,距离旁瓣限制了相位编码信号脉冲压缩的实际应用。因此,如何更好的抑制距离旁瓣成为相位编码信号脉冲压缩实际应用的关键问题。本文主要研究和分析了一种基于小波神经网络的多相码雷达信号的旁瓣抑制方法。首先从模糊函数和回波特性的角度介绍了多相编码信号的一些相关特性,并介绍了Taylor码、Frank码、P3、P4码等多相编码信号;其次介绍了多相编码信号的旁瓣抑制方法,本文主要介绍了比较常用的两种方法:直接窗函数加权方法和最小二乘失配滤波方法,并结合其原理进行了多相编码信号旁瓣抑制的仿真特性测试;再次,研究了小波分析理论和小波神经网络的学习方法,重点研究了基于BP算法的小波神经网络并提出了几种BP的算法的改进算法;最后,将改进的BP网络应用到多相编码信号的旁瓣抑制中来,并对其抗噪声性、多普勒容限性和分辨力能力进行了相关仿真试验。试验结果表明,这种小波神经网络旁瓣抑制方法具有较直接窗函数加权法和最小二乘失配滤波法更强的旁瓣抑制能力和更好的多普勒容限性。更多还原

【Abstract】 The pulse compression is an advanced technique widely applied in the modern Radar. It has effectively solved the contradiction between the radar range resolution and the average power. The phase coded singals are commonly used in pulse compression. And with the development of the digital and DSP technology, people began to seek the signal with greater pulse compression radio, therefore the polyphase coded signal received wide attention. However, their range sidelobes are too high and inadequate for most applications. So, how to minimize the peak range sidelobe of a phase coded waveform is a key to practical applications of phase coded pulse compression.This article mainly introduced and has analyzed a method of sidelobes suppression for radar polyphase code signal using wavelet neural network. First, introduce some characteristic of polyphase coded signal such as ambiguity function and echo, and introduced some polyphase coded such as Taylor code, frank code, P3, P4 code and so on. Second, intrduced two common used method of sidelobes suppression for polyphase coded singal, windowing weighted sidelobe suppression technology and least squares mismatched filtering algorithm. Combined with the principle of the two methods, we carried on the corresponding simulation. Third, we study the theory of the wavelet and the learning methed of the wavelet neural network, focusing on BP algorithm besed on the wavelet neural network and put forward several improved BP algorithm. Last, using the improved BP network for suppressing sidelobes of the polyphase coded signal, and test its resistance to noise, Doppler tolerance and ability of resolution. The result show that the wavelet network sidelobes suppression method has better characteristic of sidelobe suppression and Doppler tolerance than windowing weighted sidelobe suppression technology and iterative least squares mismatched filtering algorithm.更多还原