高动态飞行器信号捕获算法研究

发布时间：2018-06-14 15:39

本文选题：高动态飞行器 + 信号捕获　；参考：《西安电子科技大学》2014年硕士论文

【摘要】：高动态飞行器在近几年来成为各国研究的热点,通信是飞信器发展的重要保障,而信号捕获则是通信系统的第一步工作,能否实现信号的快速准确捕获,将会影响到整个通信系统的性能。飞行器的高动态包括高速度和高加速度等特点,这些特点导致了通信信号的多普勒效应,引起信号中包含多普勒频率偏移和多普勒变化率等畸变,与其他通信方式有较大差别。本文对受到多普勒效应影响的信号快速捕获问题进行了研究。首先,介绍了高动态飞行器的发展背景,分析了高动态飞行器的物理模型,根据其物理模型讨论了多普勒效应对信号的影响,并对高动态飞行器的通信信号进行了建模。然后,介绍并比较了当前对于存在多普勒频移的扩频信号的常用捕获算法,包括滑动相关法、匹配滤波法以及基于FFT的快速捕获算法等。利用离散傅里叶变换的移位性质,推导了以频谱移位代替传统载波相乘的快速算法,通过仿真验证了该算法和传统方法具有相同捕获效果的同时,提高了捕获速度。提出了利用两级FFT级联的捕获算法,对信号频谱进行相关运算,直接捕获信号的多普勒频移,以实现扩频信号的快速捕获,并将该分析了算法特点,通过仿真与传统的捕获算法在捕获性能和速度等方面进行比较。最后,介绍了分数阶傅里叶变换原理以及其离散变换的快速实现方法。介绍了传统的载波捕获方法中,基于多普勒变化率搜索的二维FFT算法。讨论了利用分数阶傅里叶变换对存在多普勒变化率的载波信号进行捕获,从原理上分析了和传统方法的异同点,并对捕获效果进行比较。提出对分数阶傅里叶变换的两种改进策略,一种是将二维FFT和FRFT相结合,分别进行多普勒变化率的粗细捕获,另一种是将搜索范围不断划分,逐步细化搜索阶数以捕获变化率。两种策略能够在提高捕获精度的同时,降低运算复杂度。本文还介绍了非纯载波信号的分数阶傅里叶变换,探讨了分数阶傅里叶变换在干扰捕获与识别方面的应用前景。
[Abstract]:In recent years, high dynamic aircraft has become the focus of research in various countries. Communication is an important guarantee for the development of the communication system, and signal acquisition is the first step of the communication system. The performance of the whole communication system will be affected by the fast and accurate capture of the signal. The high dynamic features of the aircraft include high speed and high acceleration, etc. These characteristics lead to the Doppler effect of the communication signal, which causes the distortion of the Doppler frequency offset and the Doppler change rate, which are different from other modes of communication. This paper studies the problem of fast acquisition of signals affected by the Doppler effect. First, the development background of the high dynamic vehicle is introduced, and the analysis of the development of the high dynamic vehicle is introduced. The physical model of a high dynamic vehicle is made. The effect of Doppler effect on the signal is discussed according to its physical model, and the communication signal of high dynamic vehicle is modeled. Then, the common acquisition method for the spread spectrum signal with Doppler shift is introduced and compared, including the sliding correlation method, the matched filtering method and the base. The fast acquisition algorithm of FFT, and so on. Using the shift property of the discrete Fourier transform, a fast algorithm using the frequency shift instead of the traditional carrier multiplication is derived. The simulation shows that the algorithm has the same capture effect as the traditional method and improves the capture speed. A two stage FFT cascade acquisition algorithm is proposed. The correlation operation of the spectrum is carried out to capture the Doppler shift of the signal directly to realize the fast acquisition of the spread spectrum signal. The characteristics of the algorithm are analyzed and compared with the traditional capture algorithm in the acquisition performance and speed. Finally, the principle of fractional Fu Liye transform and the fast realization of its discrete transformation are introduced. In this paper, a two-dimensional FFT algorithm based on the Doppler change rate search is introduced in the traditional carrier acquisition method. The fractional Fourier transform is used to capture the carrier signal of the Doppler change rate. The similarities and differences between the traditional method and the traditional method are analyzed in principle, and the fractional Fourier transform is put forward. The two improvement strategy is to combine the two-dimensional FFT and FRFT to capture the Doppler change rate respectively. The other is to divide the search range and gradually refine the search order to capture the change rate. The two strategy can improve the acquisition precision while reducing the complexity of the calculation. The application of fractional Fourier transform in jamming acquisition and recognition is discussed.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：V443.1;TN911.7

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