基于PL3105的电力线通信研究

PL3105是为智能控制设计的电力线通信专用芯片，具有8051指令兼容的高速微处理器、直序扩频的载波通信等强大功能．文章从硬件和软件上介绍了PL3105电力线通信专用芯片的应用．实验表明，它在电力线载波通信方面具有较大的优势．     

基于失真测度的直接扩频音频隐写分析

在利用失真测度来描述隐写引起的音频失真时,发现对同一原始音频进行多次直接 序列扩频隐写过程中,第一次隐写引起的失真最为剧烈．从直接扩频隐写的原理出发,提出了 从待检测音频提取相应失真测度作为特征向量,并利用支持向量机进行分类的隐写分析方法． 该方法不需要对原始音频进行估计．实验证明,本方法具有令人满意的性能,对不同嵌入强度 也同样有效,同时对嵌入容量的干扰提出２种改善策略．     

使用试错法加快扩频通信伪随机码捕获

An optimun search algorithm for the coherent acquisition in direct-sequence spread-spectrum （DSSS） receivers is proposed and analyzed in this paper. The system consists of two major parts： a phase region estimator and a phase alignment detector. We use an auxiliary sequence to correlate the incoming signal in the phase region estimator. Since the cross-correlation value between the auxiliary sequence and the incoming PN signal has linear magnitude, and can provide the direction for the phase updating, an optimum search algorithm, try and error method, can be adopted to obtain the phase region information of the incoming signal. The mean acquisition time is derived through the signal flow graph theory. The time is compared with that of the conventional serial search scheme, and the results show that the proposed scheme can achieve coarse acquisition significantly faster than the conventional scheme.     

混沌与 Walsh 复合扩频序列性能分析

直接序列扩频系统中,扩频序列的选择是个关键问题。扩频序列性能的好坏,直接关系到直接扩频通信系统整体性能的优劣,如抗干扰、抗衰落、同步与跟踪等性能。由于复合序列具有更高的复杂性和抗干扰能力,现已逐步代替传统的扩频序列。为此,提出一种混沌序列与Walsh序列相复合的复合序列,并对复合序列的抗干扰性能、子序列对复合序列性能的影响进行分析,仿真结果表明新的复合序列较传统序列有更强的抗干扰能力,且该复合序列的抗干扰性能不受子序列初始值影响,具有很高的应用价值。