无源定位中雷达信号的时差提取

【作者】 方强；

【导师】 周宁；

【作者基本信息】 电子科技大学 ， 通信与信息系统， 2006， 硕士

【摘要】 无源时差定位又称为双曲线定位,是一种重要的无源定位方法,它通过处理三个或更多个接收站采集到的信号到达时间数据,从而对辐射源进行定位。时差定位系统具有精度高、定位快等优点,在工程中得到了广泛的应用。但是时差定位系统的精度主要取决于时延估计的精度,因此,研究快速、准确的时延估计方法成为时差定位系统中一个十分重要的课题。实际工程中雷达信号的传播环境十分复杂,信号在传播过程中要受到反射、散射以及各种杂波的影响,因此接收机接收到的信号往往具有信噪比比较低、信号模型复杂等特点。现在常用的几种时延估计方法,只适用于信号为平稳信号,噪声为加性高斯白噪声这样比较简单的情况。像雷达信号这样复杂的传播模型,这些常用的时延估计方法就不适用了。大部分的雷达信号都是非平稳信号,但它们都具有循环平稳特性,所谓循环平稳信号是指相关函数为时间的周期函数的一大类非平稳信号。基于这样的特点本文给出了基于循环平稳性的时延估计方法。该方法不仅能够有效的进行信号的时延估计,而且该方法还可以对某些信号的参数进行估计;在抗噪性方面该方法不仅能够抑制加性平稳噪声,而且还能够抑制乘性平稳噪声。该方法计算量较小,易于工程实现,能够满足雷达对抗的实时性要求。正弦信号、线性调频信号、多项式相位信号、相位编码信号是雷达信号中常用的几种信号,对这几种信号的研究是雷达信号处理中非常重要的内容,也是实际工程的需要。因此,本文选择上述几种信号作为研究对象,对这几种信号的时延估计算法进行了建模和理论推导,给出了时延估计算法的具体表达式,并进行了计算机仿真。文章的最后进行了全文总结,指出了有待下一步研究的问题。本文提供的方法为循环平稳信号处理方法在雷达信号处理方面的应用提供了一个很好的思路和方法。更多还原

【Abstract】 Time difference of arrival (TDOA) location system, namely the hyperbola location, is an important passive location method.Using the time difference of signals arrived to three or more different stations, we can determine the position of the target wanted to be located.Because of its high precision and fast location advantages, it is widely used in practice.But its precision depends on time delay estimation, so researching fast and exact time delay estimation method become a hot topic in TDOA location system.The special radar signal environment is very complex in electronic warfare, so the received signals always have low signal noise ratio (SNR) and complex model.Under this kind of environment, the estimation precision of time delay and the capability of restraining noise fallen down in the conventional methods.Most radar signals are non-stationary signals, but they are cyclostationary signals,namely, the correlation function of radar signals is periodic function of time. Based on the cyclostationary characteristic, a novel time delay estimation method has been proposed in this thesis.The reseach work focused on the time delay estimation of the common practical radar singnals, including harmonics signal, chirp signal, polynomial phase signal, and phase-shift keying signal.The new algorithm for different radar signals are deduced in detail respectively, and simulation results are presented.The results proved that the new method is efficient for time delay and some other parameters estimation. At the same time, it can restrain multiplicative and additive noise.Generally, a nice idea and method are proposed for radar signal processing. Meanwhile, there is still a lot of work worth further research with great effort.更多还原