混沌扩频测控系统同步捕获性能分析

摘要

混沌序列在扩频测控系统中的应用引起了人们的广泛兴趣，混沌扩频测控系统的捕获性能和跟踪性能是学界关注的重点。由于数字化混沌序列相关函数旁瓣具有随机性，使得扩频系统的信号捕获过程，除了受加性噪声影响之外，又增加了一个影响因素。根据系统捕获原理与混沌码特性，借助于混沌码模糊函数的概念，提出了混沌码相关函数旁瓣随机性影响下检测概率、虚警概率以及捕获时间的计算方法，推导得到了相应的计算公式，探讨了混沌扩频测控系统的信号捕获性能。结果表明，混沌码相关函数随机性的存在使检测概率和虚警概率有所增大，并使捕获时间产生变化；与加性噪声相比，其影响通常较小甚至可以忽略。该结果可以为混沌序列在扩频测控系统中的应用提供理论支持与参考。%Chaotic sequence used as the spread spectrum code in spread spectrum system has gained wide-spread attention because of its excellent characteristics. Besides the bit error rate ( BER ) , which is the main consideration in spread spectrum communication systems, the acquisition and tracking performances are more important in spread spectrum Telemetry Tracking and Control( TT&C) system. In spread spectrum system, signal acquisition is affected by not only additive white Gaussian noise( AWGN) , but also the ran-domness of digital chaotic sequence. The signal acquisition performance is analyzed in this paper. With the aides of chaotic sequence ambiguity function, the effections of chaotic sequence randomicity on detection probability, false alarm probability and acquisition time are studied. According to the results in this paper, the effection of chaotic sequence correlation randomicity is neglectable compared with that of AWGN. The results in this paper provide support and reference for the application of chaotic sequence in TT&C system.