面向临近空间的直扩信号快速同步技术研究

发布时间：2018-08-02 09:30

【摘要】：扩频技术在航天航空以及其它相关通信领域都已经取得了广泛的使用,其中扩频信号的同步技术的是扩频通信系统的关键所在,扩频信号的同步主要包括了捕获以及跟踪两个处理过程。在临近空间的测控通信中,由于载体的有着很高的移动速度,导致接收信号有很大的多普勒频偏,使得扩频信号的捕获要同时完成载波及其伪码相位的捕获,并且可能出现的低仰角环境造成的多径效应及低信噪比也大大增加了捕获与跟踪的难度。文章主要就临近空间环境下突发传输扩频通信的同步技术展开研究,首先对于直扩系统的原理及其特点进行了简单的介绍,同时也对扩频通信中常见的伪随机序列的原理进行了论述。然后针对高动态环境下,对基于FFT的快速捕获算法以及锁相跟踪环路进行深入的研究分析。本文最后对突发传输系统的捕获与跟踪模块进行设计,在确定传输帧结构的前提下,对之前讨论的几种快速捕获算法进行性能与复杂度分析,选取合适的算法及对应的参数,实现高动态低信噪比下的可靠传输,并在不同的信道环境下对所设计的同步模块进行仿真验证与总结。
[Abstract]:Spread spectrum technology has been widely used in aerospace and other related communication fields, among which the synchronization technology of spread spectrum signals is the key of spread spectrum communication system. The synchronization of spread spectrum signals mainly includes two processing processes: acquisition and tracking. In the measurement and control communication in the adjacent space, because of the high moving speed of the carrier, the received signal has a very large Doppler frequency offset, so the acquisition of the spread spectrum signal must complete the acquisition of the carrier and its pseudo-code phase at the same time. The multipath effect and low signal-to-noise ratio (SNR) caused by low elevation environment also greatly increase the difficulty of acquisition and tracking. In this paper, the synchronization technology of burst transmission and spread spectrum communication in the near space environment is studied. Firstly, the principle and characteristics of the direct spread spectrum system are briefly introduced. At the same time, the principle of pseudorandom sequence in spread spectrum communication is discussed. Then, the fast acquisition algorithm based on FFT and the phase-locked tracking loop are studied and analyzed in high dynamic environment. Finally, the acquisition and tracking module of burst transmission system is designed. On the premise of determining the transmission frame structure, the performance and complexity of several fast acquisition algorithms discussed before are analyzed, and the appropriate algorithm and corresponding parameters are selected. The reliable transmission with high dynamic and low signal-to-noise ratio is realized, and the simulation of the designed synchronization module in different channel environment is carried out.
【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

【相似文献】