共查询到17条相似文献,搜索用时 62 毫秒
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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。 相似文献
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在现有的非相干混沌通信系统中,用于传输参考信号的比特能量无法在接收端相关器被恢复出来,因此能量效率不高。针对这一问题,利用混沌序列前、后交换得到的新序列与原序列近似正交的特性,将参考信号与信息调制信号叠加在同一时隙传输,设计了一种置换相关键控混沌通信系统。在加性高斯白噪声信道中,该系统能从接收端相关器恢复全部的发送比特能量,具有比同类方案更高的能量效率。对误码率公式做了理论推导,对噪声性能进行了仿真实验,结果表明,与现有同类非相干混沌通信方案相比该方案具有更低的误码率。 相似文献
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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. 相似文献
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分析了Liu混沌系统的特性,讨论了一种观测器同步设计方法.首先对响应系统状态进行重构,然后通过极点配置方法,实现两个混沌系统的状态渐进同步,并通过数值仿真对理论分析加以验证.提出利用Liu混沌系统同步进行图像保密通信的方法,在发送端利用Liu混沌信号掩盖坐标变换后的数字图像信号,在接收端能准确地恢复原始图像信号.仿真结果表明了提出的图像保密通信方法具有很好的保密性. 相似文献
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水声信道作为目前已知最严酷、最复杂的无线通信信道之一,具有强多途干扰、时—频率双扩展、高噪、带宽窄等特征。水声信道的时变特性,使得估计与跟踪信道很困难,因此,研究无需信道估计与均衡的非相干稳健水声通信调制方法具有重要的意义。首先介绍了基于正交频分复用(OFDM)和扩频调制的水声调制技术的研究进展,然后,分析了差分混沌移位键控在水声信道下的可行性,提出了两种基于OFDM的多载波差分混沌移位键控方案,给出两个方案的调制解调器原理。在时—频双扩展信道和水声信道下,对两个方案进行了性能仿真和分析。性能结果表明所提出的方案在水声信道下具有良好的稳健性。 相似文献
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To evaluate the security of a chaos optical communication system employing the polarization-shift keying (PolSK) modulation technology, its chaos characteristic needs to be verified. In this paper, an analysis was done for the signal of this system. Three methods were used to judge whether the signal was maintaining chaos characteristics or not: watching the strange attractor in three-dimensional phase space, computing the largest Lyapunov exponent by the equation which meets and Wolf's method, and evaluating the self-power spectrum density function. As a result, the strange attractor was clearly watched, the largest Lyapunov exponent was positive 0.0364 and 0.0106 respectively,and the self-power spectrum was wide and continuous with the noise background. The evaluation of chaos for the signal transmitted in the system is therefore presented. On the other hand, the minimal embodied dimension of the signal was given by the false nearest neighbors (FNN) method and it reached 6, which showed the higher dimension chaos characteristics of the system.Adding the analysis of the ability of anti-attack for the system, it is concluded that the system has higher security than the normal chaos masking schemes. 相似文献
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In this paper, we propose an anti-noise modem based on the improved M-ary position phase shift keying (MPPSK) for visible light communication (VLC) systems. The line spectral interferences in the original MPPSK are theoretically analyzed and approximately mitigated by adopting a set of improved waveform samples. Then, within one symbol duration, the peak envelopes of the received signals are captured at each of synchronization bit with a quantity of sampling offsets to improve the proportion of the reliable data tones. In addition, a novel demodulation scheme using an amplitude-position detector based on soft decision is proposed to recover the MPPSK symbols, which can minimize the contamination influence of channel noise on symbol decision. With this scheme, the false alarm error and wrong slot error caused by the multipath fading in VLC channel can be effectively corrected and the bit error rate (BER) performance of the system is significantly improved. Simulation results demonstrate that the proposed scheme reduce the required signal-to-noise ratio (SNR) at least by 2 dB for BER = 10−4, which show the feasibility and validity of this anti-noise modem. 相似文献