高动态下扩频同步系统的性能研究

发布时间：2018-04-17 23:02

本文选题：高动态 + 捕获　；参考：《西安电子科技大学》2014年硕士论文

【摘要】：扩频测控体制是如今外测系统常采用的通信体制。由于飞行器相对地面高速飞行引发的高动态性,会导致极大的频率偏移和频偏变化率,使得扩频信号的同步十分困难,采用传统的同步方法,同步时间很长且误码率很大。因此扩频系统载波同步结构的设计至关重要。本论文首先介绍了扩频技术的基本原理和高动态基本概念。在第三章中,本文列举了扩频粗同步常用的几种捕获方法,并着重对基于FFT的捕获方法的系统结构的原理进行了理论说明,对高动态下扩频信号捕获性能进行理论分析和仿真验证,并给出扩频信号捕获结构相关参数(包括伪码相关积分长度、频率搜索步进单元)的设计依据。在第四章中,本文列举了扩频细同步常用的几种跟踪方法,并对扩频信号载波跟踪中的关键问题(包括鉴别器算法、环路滤波器等)的进行理论分析和仿真验证,对高动态下扩频信号跟踪性能进行仿真研究。根据第三、四章的研究结果,给出本课题使用的扩频同步系统结构、鉴别器算法、及相关参数选择。在扩频信号捕获上,采用了利用FFT谱分析并行搜索的捕获方法,将载波频率、伪码相位的二维捕获过程转变为伪码相位的一维捕获过程,从而达到缩短捕获时间的目的。在扩频信号跟踪方面,选用了锁频环引导锁相环的载波跟踪结构,采用了一种改进的鉴相器算法和叉积自动频率跟踪算法,并给出了该扩频同步系统在高动态下的系统性能仿真。
[Abstract]:Spread spectrum measurement and control system is a communication system that is often used in the field measurement system.Because of the high dynamic characteristics caused by the aircraft flying at high speed relative to the ground, it will lead to great frequency offset and frequency offset change rate, which makes the synchronization of spread spectrum signals very difficult. Using the traditional synchronization method, the synchronization time is very long and the bit error rate is very large.Therefore, the design of carrier synchronization structure in spread spectrum system is very important.This paper first introduces the basic principle of spread spectrum technology and the basic concept of high dynamic.In the third chapter, this paper enumerates several common acquisition methods of spread spectrum coarse synchronization, and emphatically explains the principle of system structure based on FFT.The acquisition performance of spread spectrum signals under high dynamic conditions is theoretically analyzed and simulated, and the design basis of acquisition structure parameters (including pseudo-code correlation integral length, frequency search step unit) is given.In the fourth chapter, several common tracking methods of spread spectrum fine synchronization are listed, and the key problems in spread spectrum signal carrier tracking (including discriminator algorithm, loop filter and so on) are analyzed and simulated.The tracking performance of spread spectrum signal in high dynamic state is simulated.According to the results of the third and fourth chapters, the structure of the spread spectrum synchronization system, the discriminator algorithm, and the selection of related parameters are given.In the acquisition of spread spectrum signals, the acquisition process of carrier frequency and pseudo code phase is transformed into one dimensional acquisition process of pseudo code phase by using FFT spectrum analysis and parallel search method, so as to shorten the acquisition time.In the aspect of spread spectrum signal tracking, the carrier tracking structure of frequency-locked loop guided phase-locked loop is selected, and an improved phase discriminator algorithm and cross-product automatic frequency tracking algorithm are adopted.The performance simulation of the spread spectrum synchronization system under high dynamic condition is also given.
【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】：TN914.42

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