Approach to blind estimation of the PN sequence in DS-SS signals with residual carrier

This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise （PN） sequence estimation in low signal to noise ratios （SNR） direct sequence spread spectrum （DS-SS） signals with residual carrier. This approach needs some given parameters, such as the period and code rate of PN sequence. The received signal is firstly sampled and divided into non-overlapping signal vectors according to a temporal window, whose duration is two periods of PN sequence. An autocorrelation matrix is then computed and accumulated by those signal vectors one by one. The PN sequence with residual carrier can be estimated by the principal eigenvector of the autocorrelation matrix. Further more, a digital phase lock loop is used to process the estimated PN sequence, it estimates and tracks the residual carrier and removes the residual carrier in the end. Theory analysis and computer simulation results show that this approach can effectively realize the PN sequence blind estimation from the input DS-SS signals with residual carrier in lower SNR.

基于矩阵的混合型数字匹配滤波器的研究

针对测井信号扩频传输的实际需求,在FPGA芯片上设计并实现了一种改进的混合型数字匹配滤波器。匹配滤波相干过程采用递归化矩阵运算的方式进行,并将滤波器中多路乘加器计算求值的结构改用查表寻值形式,以同时满足井场对简化设备结构与保证工作速率的要求。测试结果显示,该结构数字匹配滤波器的处理效果能满足设计要求。

载人航天空空通信子系统及其关键技术

介绍了实现神舟运输飞船与天宫目标飞行器间数据通信和传输的空空通信子系统的构成,以及空空通信机的功能及其主要性能指标。空空通信子系统采用抗干扰能力强、保密性优的直接序列扩频通信技术。分析了其中的核心中频解扩解调中的伪码同步和载波同步等关键技术,应用数字解调方案降低了子系统调试难度,提高了可靠性。