一种新的混沌在直接序列扩频通信系统中的应用

二进制混沌键控系统信息传送速率不高,为了提高信息传送速率,本文提出了多进制混沌键控系统的方案,并对其频带利用率,抗干扰性能及其同步方式做出了分析。     

二进制混沌键控信号的最佳解调

本文通过对二进制混沌键控（２ＣＳＫ）系统同步误差信号的分析，提出２ＣＳＫ的最佳解调方案，同时给出了以Ｌｏｒｅｎｚ电路为例的计算机模拟结果。     

一种新的混沌键控方案——分段移位混沌键控

为了进一步提高混沌通信系统的数据传输率,提出了一种新的混沌键控方案——分段移位混沌键控SSCSK,它是一种多进制调制方案。将SSCSK中的参考信号等分成M个信号段,根据传送的M进制数字码元,将M个信号段循环左移n（0≤n〈M）段,即形成信息携带信号。通过对其误码性能进行仿真分析可知,在相同的误比特率条件下,在信噪比要求上,二进制SSCSK比DCSK方案大约小3dB,四进制SSCSK的误比特率与DCSK方案接近,在混沌信号长度相同的条件下,四进制SSCSK的信息传输速率比DCSK提高了1倍。     

无信号内干扰的相关延迟键控混沌通信方案

该文提出一种名为无信号内干扰相关延迟键控(Correlation-Delay-Shift-Keying with No Intrasignal Interference, CDSK-NII)的新型混沌通信方案。采用重复混沌序列为参考信号,同时利用零和序列确保参考信号与信息信号严格正交,CDSK-NII能够在解调过程中消除信号内干扰。在高斯白噪声信道和Rayleigh衰落信道中分析CDSK-NII的比特误码率。实验结果表明:由于无信号内干扰,CDSK-NII的比特误码率低于CDSK和通用相关延迟键控(GCDSK);随着复帧长度的增加,CDSK-NII的性能将进一步提升,比特误码率低于参考自适应相关延迟键控(RA-CDSK)。     

基于混沌移位键控调制的卫星隐蔽通信性能分析

文章提出了一种基于相干混沌移位键控信号的卫星隐蔽通信方案,并建立了系统模型,然后采用离散基带信号分析了其隐蔽性能、抗干扰性能以及相关参数的选取.理论分析和仿真结果表明使用相干混沌移位键控信号完成卫星隐蔽通信具有较好的隐蔽性和抗干扰性,为基于混沌调制技术的卫星隐蔽通信提供了理论支持.     

一种新型CD-QCSK混沌保密通信系统设计

针对现有混沌键控、混沌遮掩和混沌参数保密通信系统存在的一些缺点和实际应用的缺陷,提出了一种新型的混沌保密通信系统方案CD-QCSK系统的具体设计.同时对这个系统的实现原理进行了详细的推导,并基于Matlab/Simulink软件仿真实现了这个保密通信方案的信号传输,对其系统性能进行实验仿真分析,列举出了运用混沌加密前后效果图.该混沌键控系统同时兼具CDSK系统保密性高和QCSK误码率低的优点,系统的误码率性能和保密性也都有所提高,并且系统的传输速率是原有键控方式的4倍.     

基于耦合映象格子的混沌键控技术研究

提出一种基于耦合映象格子正反相同步的混沌键控方案,可利用系统提供的正反相同步信号提取出所传输信息,该方案有效地提高了信息的安全性。     

通用差分混沌键控通信系统及其性能分析

在各种混沌通信方案中,差分混沌键控混沌采用了易于实现的非相干解调,因而成为了混沌超宽带通信研究的热点。文章基于传统差分混沌键控通信提出一种通用差分混沌键控通信系统,该系统包含了多种差分混沌键控通信系统。文中理论分析了该系统中每比特采样点数、每符号比特数和信号占空比三个参数对于系统性能的影响,通过仿真证明了理论分析的正确性,最后分析了仿真和理论分析差异产生的原因。     

一种新的混沌数字保密通信实现方案

针对差分混沌键控（DCSK）的保密性低,数据传输速率不高等缺点,这里设计并研究了一种新的混沌键控调制方式—调频相关延迟键控（FM-CDSK）通信方案,该方案同时兼具CDSK和FM-DCSK的优点。通过仿真分析验证了该系统在数据传输速率和保密性等方面较DCSK和CDSK都有所提高,传输速率更是比原有键控方式提高了2倍,并且利用该混沌调制方式很好的实现了图像信号的保密传输,验证了该系统在数字保密通信中的可实现性。     

利用差动混沌键控实现保密通信

本文提出了一种利用差动混沌键控来实现保密通信的方法，利用二进制信号直接对混沌载波进行调制，达到保密通信的目的，并利用计算机对该方案进行了数值模拟。     

基于CSK调制的可见光通信系统的盲检测算法研究

基于IEEE 802.15.7标准中色移键控(CSK)调制通信系统的检测方案,利用CSK调制的特性,提出了一种新的盲检测算法。该盲检测算法,利用CSK调制信号的性质在没有信道信息的情况下也可以对CSK信号进行解调,省略了信道估计模块,简化了系统。仿真发现,这种盲检测算法具有较好的误码率性能。     

Chaos shift-keying encryption in chaotic external-cavitysemiconductor lasers using a single-receiver scheme

In this letter, we numerically show that chaos shift-keying (CSK) encryption can be achieved by using a single receiver, thus providing a better performance when comparing with the traditional CSK scheme based on two receivers. We analyze the rate equation model for two unidirectionally coupled single-mode external-cavity semiconductor lasers operating in a chaotic regime. The message is encoded in the emitter by slightly varying its injection current. We find that under appropriate conditions, the receiver laser synchronizes to the chaotic emitter, filtering the encoded message and allowing message extraction     

Synchronization of chaotic injected-laser systems and itsapplication to optical cryptography

We demonstrate that two chaotic systems, each made by two coupled semiconductor lasers, can be synchronized using direct-optical feedback. The robustness of the proposed synchronization scheme against mismatch of source parameters and difference in starting conditions is tested by numerical simulations. Applications to secure data transmission are proposed, namely chaotic masking and chaotic shift keying (CSK)     

Multi-state chaos-shift-keying modulation system using feedbacksynchronising Chua's circuit

A new type of chaos-shift-keying (CSK) modulation, called multi-state CSK, is presented for the first time. In a classical CSK communication system, using this type of modulation combined with feedback synchronisation, the data rate can be greatly increased. Laboratory test results conform very well with theoretical analysis     

Multi-State Chaos-Shift-Keying Modulation System: Analysis and Realization

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A Near-Optical Noncoherent Chaos-Based Communication Scheme

In this paper we introduce a method for improving the performance of noncoherent chaos-based communication systems. This method involves transforming chaotic signals into predefined patterns according to the relative magnitudes of the signal samples. First, for large spreading factors, the transformation leads to a large correlation between two different chaotic signals having the same distribution. This property can be used to recover the information in a noncoherent system. If the chaotic map and the transformation function are known, we can generate another chaotic signal to construct the reference signal for use in the correlator. In this scheme, both the synchronization circuit and the referencetransmission are not required. This scheme is referred to as the near-optimal noncoherent (NON) scheme. Second, for small spreading factors where high autocorrelation of the transmitted signals cannot be achieved, we propose a near-optimal noncoherent scheme with transmitted reference (NON-TR). For comparison, the corresponding performance bound using coherent detection is also given. This reference scheme is called the nearoptimal coherent (NOC) scheme. It can be shown that the NON scheme can achieve a similar performance as the chaos shift keying (CSK) system.     

Effects of message encoding and decoding on synchronized chaotic optical communications

Chaotic optical communication at 2.5 Gb/s is experimentally investigated using three major encoding and decoding schemes, namely chaos shift keying (CSK), chaos masking (CMS), and additive chaos modulation (ACM). The effects of message encoding and decoding on the chaotic dynamics, the chaos synchronization, and the chaotic communication performance are compared among the three schemes. In the schemes of CSK and ACM, it is found that a small amount of message injected into the chaotic dynamics can increase the complexity of the chaotic state dramatically. In the CMS scheme, the chaotic dynamics are found not to be influenced by the encoded message. The synchronization quality deteriorates dramatically with an increase in the message strength in CSK and CMS. The ACM scheme is found to have the best synchronization quality among the three schemes when there is an encoded message. Message recovery is demonstrated for each of the three schemes. The ACM scheme is found to have the best communication performance.     

非相干的CSK通信系统及其性能分析

提出一种带可调权值的非相干CSK（chaos shift keying）通信系统，分析了其在多径信道环境下的理论误码性能并仿真，结果表明系统的误码性能较好。当权值满足一定条件时，系统的多径误码性能和DCSK（differential chaossllift keying）通信系统的相同，并且其AWGN（加性高斯白噪声）误码性能优于一些已有的非相干CSK通信系统。     

一种用于无人机的目标颜色核相关跟踪算法研究

利用CSK算法从图像碎片中提取运动目标的一个最小二乘分类,引入多通道颜色特征标定运动目标,通过当前图片碎片中的核函数周期性假设循环结构,一定程度拟补CSK算法使用目标灰度特征描述能力的不足。采用PCA降低特征维度并去除特征冗余信息,提高分类器参数更新速度,解决了CSK算法分类器参数更新线性化、无法适应目标发生较大变化时的运动目标跟踪问题。利用benchmark测试平台的算法集与测试数据集进行了实验,目标颜色核相关跟踪算法（TCKCT）的实验结果表明,对光照变化、背景杂乱、目标形变、目标运动速度较快、目标运动幅度较大的情况下,算法都有较好的跟踪效果。无人机跟踪遥控小车的物理实验结果,进一步验证了TCKCT算法特性,良好的实时性能够满足无人机目标跟踪要求,具有良好的实际应用前景。     

非相干光反馈的半导体激光器混沌保密通信性能分析及其仿真

首先研究了非相干光反馈同步系统内部参数失配对系统同步性能的影响,并与相干光反馈的完全同步系统以及广义同步系统进行了比较,其次研究了非相干光反馈采用三种不同的信号调制解调方式(CSK,CMS,ACM),对三种不同频率(250 MHz,2.5GHz和12.5GHz)的信号进行了调制解调。通过MATLAB仿真实验可知,非相干光反馈混沌同步系统相对于相干光反馈完全同步系统更易于实现,同时保留了一定的对参数失配的敏感特性,从而确保了该系统比相干光反馈广义同步具有更高的安全性;在信号解调时,CSK只能解调出250MHz信号,CMS能解调出2.5GHz信号,ACM能够解调出高达12.5GHz的信号。