一种适用于低信噪比环境下的差分相关捕获方法  

An adaptation of the low SNR differential correlation acquisition method

作　　者：尚素绢 许耀华[1] 罗炬锋 邱云周 

机构地区：[1]教育部智能计算与信号处理重点实验室(安徽大学),安徽合肥230026 [2]上海物联网有限公司,上海200050

出　　处：《电子技术应用》2017年第5期110-113,118,共5页Application of Electronic Technique

基　　金：上海市科技重大项目(15DZ1100400)

摘　　要：直接扩频系统中的捕获是一项非常关键的同步技术。常用差分处理来消除频偏对峰值的影响,然而一般差分捕获算法随着伪码的增长、信噪比的降低都会导致信噪比的损失很大。提出一种改进的差分捕获算法,基于差分相关的M阶无偏自相关捕获算法(MUAC-DF),将信号和伪码相乘消除伪码信息后做M阶无偏差分自相关,在一定程度上弥补了差分带来的信噪比损失,提高了抗噪性能;详细介绍了其数学模型,并且从理论上分析了MUAC-DF算法性能;最后在相同条件下进行仿真验证。实验结果表明,MUAC-DF捕获算法比一般的差分非相干码捕获技术性能更加优越,其捕获性能有4~5 dB的改善,更适应于低信噪比条件下工作。Acquisition is a key technology in DSSS system. The differential correlation is usually employed to eliminate the effect of frequency deviation. However, as the length of pseudo-code grows and the decrease of the SNR, the traditional differential acquisi- tion algorithms will result in great loss of SNR. This paper presents an improved differential acquisition method, named as MUAC- DF. In the proposed method, the input signal is multiplied by the complex conjugate of the pseudo-code to eliminate its effect. Af- ter that, the product is applied to the M-orders Unbiased Auto-Correlation to compensate the SNR loss caused by the differential process. By means of mathematical model to analyze its acquisition performance. MUAC-DF acquisition algorithm is compared with the differential coherent and non-coherent acquisition algorithms through simulation. The simulation results indicate that this algo- rithm is approximately 4-5 dB superior to the traditional differential acquisition algorithms in improving acquisition sensitivity and more adaptive to work under low SNR.

关 键 词：直接序列扩频 长伪码捕获 低信噪比 差分相关捕获 

分 类 号：TN914.42[电子电信—通信与信息系统]