基于二阶采样的直扩码分多址系统伪随机码捕获方法

针对直扩码分多址系统提出了一种基于二阶采样技术和模拟匹配滤波器的数模混合型伪随机码捕获方法,详细分析了多址干扰下捕获检测量的统计特性,在此基础上推导出伪随机码捕获的检测概率和虚警概率的理论公式.该捕获方法采用二阶采样和符号交替实现中频信号的正交分解,再利用模拟匹配滤波器在模拟域计算接收信号与本地扩频码的相关值.与基于数字匹配滤波器的全数字捕获方法相比,该方法无需正交解调器和高速A/D转换器,而且具有高速、低功耗等优点.

PN Code Acquisition Method Based on Second-Order Sampling in DS/CDMA Systems

A new mixed analog-digital PN code acquisition method based on the second-order sampling technology and analog matched filters is presented for DS/CDMA systems.The statistical characteristics of acquisition-decision variable are analyzed in detail.And on the basis of the analysis,the detection probability and false alarm probability of PN code acquisition are derived in presence of Multiple Access Interference(MAI).This method directly makes quadrature demodulation of the IF signal by utilizing the second-order sampling and sign-alternating,and then calculates the correlation value between the receiver signal and the local spreading code in analog domain.Compared with the all digital method based on digital matched filter,this method can excuse the quadrature-demodulator and ADC and it has the advantages of low power dissipation and high speed.