一种保密通信系统的研究

基于混沌同步的保密通信方式相比传统保密通信方式有很大的优势,发展前景光明。通常混沌同步保密通信方式用混沌掩盖来实现,需要两个信道,其中一个信道传输混沌同步信号使系统保持同步,另一路则传输用混沌信号掩盖后的保密信息。在频谱资源日益紧张的情况下,由于这种通信方式对于信道资源的利用率相对较低,因此经济效益较差。本文提出了一个新的系统,用一个信道轮动传输信息和同步信号,对系统进行了详细分析,重点研究了系统传输的时隙分配并给出了仿真验证,证明了该系统能极大地提高信道利用率,同时对该系统的实际应用作了详细分析。     

激光耦合同步及其在光纤混沌保密通信中的应用

本文建立了光纤混沌保密通信耦合同步系统模型,实现了外部光注入分布反馈半导体激光器激光混沌在长距离光纤传输中的耦合同步,证明了光纤的交叉相位调制是限制激光混沌在光纤传输中同步的主要原因,导出了这种传输的极限.该同步系统在长距离光纤混沌模拟和数字保密通信中的数值模拟表明,该系统确有较高的保密性能和反破译能力.光纤混沌保密通信是可以实现的.     

基于输出控制的混沌同步保密通信系统

该文提出一种基于混沌系统输出线性化的反馈控制方法,将混沌系统的非线性部分线性化,从而将复杂的非线性混沌系统的同步问题转化为简单的线性混沌系统的稳定性问题,然后通过极点配置理论,用线性化的方法同步两个非线性混沌系统。基于这种同步方法设计出混沌保密通信系统,系统的一条通道用来传输输出信号,另一条通道传输通过遮掩和调制隐藏后的信息信号。仿真结果表明这种保密通信系统是有效的。     

安全性增强的双向长距离混沌保密通信

基于混沌同步,构建安全性增强的双向长距离混沌保密通信系统。结果表明:在合适的双混沌光注入参数下,驱动激光器(DL)可以产生低时延特征(TDS)、宽带宽的混沌信号;DL输出的混沌信号注入到2个响应激光器(RLs)中,通过优化注入参数,2个RLs可输出TDS更低、带宽更宽的混沌信号,且2个混沌信号在实现高质量混沌同步的同时与DL输出混沌保持极低的相关系数(小于0.1);基于2个RLs之间高质量的混沌同步,可实现安全性增强的双向远距离混沌保密通信。采用色散位移光纤作为传输信道,20Gbit/s的信息在传输120km后,解调信息的Q因子大于6;而采用普通单模光纤作为传输信道,1Gbit/s的信息在传输140km后,解调信息的Q因子大于8。     

电子信息保密通信传输链加密方法改进研究

在目前的电子信息保密通信传输链加密工作中,常常使用电路混沌作为数据加密法,但电路混沌对电路高衰变存在限制,在通信传输中存在吞吐量不足问题。因此提出新的电子信息保密通信传输链加密方法。首先定义完美保密性,通过加密密钥完成信息保密,同时采用半导体激光器来代替传统电路混沌,建立激光混沌模型,实现电子信息保密通信传输链的加密。为验证改进方法的有效性,设计仿真实验,在不同的发射功率和保密中断概率下对比不同方法加密性能。实验结果得出,所提方法吞吐量更多,性能更好,具有应用有效性。     

两类混沌激光保密通信方案的性能分析

半导体激光器在外加扰动下,可以产生高维宽带的混沌激光信号,是实现高速保密通信的理想载波。本文数值研究了混沌调制和混沌隐藏两种信息加载方式下的混沌激光保密通信系统的性能,分析了两种信息加载方式下系统分别传输正弦信息和数字信息时的信噪比和Q因子的变化情况,研究了两种信息加载方式下系统的相关系数随调制深度的变化趋势。结果表明,不同的调制深度或调制频率/速率都会影响系统的性能,且混沌调制方式的系统性能优于混沌隐藏方式。     

用于保密通信系统的混沌自适应逆控制方法

利用自适应逆控制方法设计混沌系统的噪声消除器,实现了混沌掩盖保密通信.针对混沌掩盖保密通信中含有扰动和噪声的混沌加密信号,设计了自适应噪声消除器,有效消除信号传榆中的扰动与噪声,恢复初始的信息信号,从而实现系统的同步.通过MATLAB数值仿真证实了该方法的可行性和有效性.该方法有效克服了通信系统中信道噪声对混沌同步和信息传输的干扰,并且同步速度快,在信道噪声普遍存在的情况下,能够精确传输信息.     

基于广义观测器实现混沌系统的同步及信息传输

将保密通信问题看成是信息信号同步问题,从全新的角度提出了一种基于广义观测器的保密通信系统.首先在不改变混沌发送系统的混沌特性的前提下,将信息信号注入到混沌发送系统中,并将其看作系统的状态量;然后在接收端设计广义观测器;最后根据发送端传来的隐藏有信息信号的混沌输出信号同步出混沌系统的状态和信息信号.此方法不需要单独设计加密解密算法,而是将收发端混沌系统的同步与信息传输用同步方法一次实现.对系统的仿真证明了该方法的有效性.     

一个混沌保密通信方案的改进

对文献[1]中的一个方案作了改进。用混沌映射信号作保密通信系统的调制载波,对待加密传输的信息信号进行调制,不需要用其它混沌同步方法,利用模运算在接收端直接完成混沌载波的恢复,从而恢复信息信号;为了更好地隐匿信息信号特征,借鉴混沌掩盖对信息信号幅度进行限制,使密文完全随机化。仿真结果表明:该加密系统加密效果好,且能抵御密码分析。     

基于Lorenz系统切换混沌同步的保密通讯

该文提出利用Lorenz系统切换混沌同步实施保密通讯的方法.构建了有一定关联的两个Lorenz混沌系统,并通过选择器在系统间随机切换;用同一种控制方法既能实现不同Lorenz系统的混沌同步,又能实现相同Lorenz系统的混沌同步;发送系统可以在Lorenz混沌系统间随机转换,传输信道中混沌调制信号也随之不断变化;接收系统将混沌调制信号解调后,即可获取有用信号.由于发送系统的可选择性,导致保密信号的多样性和随机性,因此该保密通讯方法具有更好的保密性能.     

An X‐Band Carbon‐Doped InGaP/GaAs Heterojunction Bipolar Transistor MMIC Oscillator

This paper addresses a fully‐integrated low phase noise X‐band oscillator fabricated using a carbon‐doped InGaP heterojunction bipolar transistor (HBT) GaAs process with a cutoff frequency of 53.2 GHz and maximum oscillation frequency of 70 GHz. The oscillator circuit consists of a negative resistance generating circuit with a base inductor, a resonating emitter circuit with a microstrip line, and a buffering resistive collector circuit with a tuning diode. The oscillator exhibits 4.33 dBm output power and achieves ?127.8 dBc/Hz phase noise at 100 kHz away from a 10.39 GHz oscillating frequency, which benchmarks the lowest reported phase noise achieved for a monolithic X‐band oscillator. The oscillator draws a 36 mA current from a 6.19 V supply with 47.1 MHz of frequency tuning range using a 4 V change. It occupies a 0.8 mm × 0.8 mm die area.     

Longitudinally Excited CO<Subscript>2</Subscript> Laser with Short Laser Pulse like TEA CO<Subscript>2</Subscript> Laser

We have developed a longitudinally excited CO₂ laser with a short laser pulse similar to that of TEA and Q-switched CO₂ lasers. A capacitor transfer circuit with a low shunt resistance provided rapid discharge and a sharp spike pulse with a short pulse tail. Specifically, a circuit with a resistance of 10 M Ω provided a spike pulse width of 103.3 ns and a pulse tail length of 61.9 μs, whereas a circuit with a shunt resistance of 100 Ω provided a laser pulse with a spike pulse width of 96.3 ns and a pulse tail length of 17.2 μs. The laser pulses from this longitudinally excited CO₂ laser were used for processing a human tooth without carbonization and for glass marking without cracks.      

Ku波段上变频组件的设计

介绍了Ku波段上变频组件的设计与制作,整个组件由低相噪振荡器、滤波器、功分器、功率放大器、PIN开关、上变频器等部分组成。文章分别对一些主要部件进行了简要的理论分析,并给出微波电路的结构形式,最后给出样品的测试结果。     

Performance analysis by simulation of floating-gate MOSFETs applied on a bidirectional associative memory architecture

Floating-gate MOSFETs (FGMOSFETs) are devices that can be electrically programmable and have a non-volatile characteristic. This feature can be adopted to configure a basic cell performing as a variable resistance that can be applied in artificial neural networks as a synapse. Based on a simple model and considering the coupling coefficient of the structure as the gain of a voltage controlled voltage source, the electrical characteristics of a floating-gate MOSFET can be simulated in PSpice and an artificial neural net, such as the bidirectional associative memory (BAM), can be implemented. Therefore a performance analysis of the net may be done with different sets of threshold voltages for the FGMOSFETs configured as a CMOS inverter used as a synapse. The objective is to know pattern pairs in a bidirectional way. The result is a correlation matrix for the BAM as a function of an electrical parameter of the devices, which is directly related to the respective matrix calculated by the matrix dot product, using the method outlined by Kosko.     

A 0.13 μm CMOS UWB RF Transmitter with an On‐Chip T/R Switch

This paper presents a fully integrated 0.13 μm CMOS MB‐OFDM UWB transmitter chain (mode 1). The proposed transmitter consists of a low‐pass filter, a variable gain amplifier, a voltage‐to‐current converter, an I/Q up‐mixer, a differential‐to‐single‐ended converter, a driver amplifier, and a transmit/receive (T/R) switch. The proposed T/R switch shows an insertion loss of less than 1.5 dB and a Tx/Rx port isolation of more than 27 dB over a 3 GHz to 5 GHz frequency range. All RF/analog circuits have been designed to achieve high linearity and wide bandwidth. The proposed transmitter is implemented using IBM 0.13 μm CMOS technology. The fabricated transmitter shows a ?3 dB bandwidth of 550 MHz at each sub‐band center frequency with gain flatness less than 1.5 dB. It also shows a power gain of 0.5 dB, a maximum output power level of 0 dBm, and output IP3 of +9.3 dBm. It consumes a total of 54 mA from a 1.5 V supply.     

用平衡树实现集合运算的研究之三

在上篇Search(f,r,a)函数基础上对平衡树的插入算法Inseart(r,a)进行了深入的研究.首先用Search(f,r,a)函数判别a是否在Tr中,若a已在Tr中插入结束,否则Search(f,r,a)函数给出a应插入于Tr中的位置f,据f的不同情况实施插入.在Inseart(r,a)算法中,引入了Inseartasleaf(f,a)过程,对该过程中的Inseartasleaf31(f,a)算法进行了详细论述,最后给出了Inseart(r,a)时间复杂度的证明.     

并行AVS实时编解码器设计与实现

介绍了一种并行AVS实时编码器的设计,它包括音视频数据输入、音视频编码、传输流系统复用器、输出和控制部分,其中重点介绍了视频编码器和传输流系统复用器的设计和实现.实验结果证明,实现标清AVS实时编码器是可行的.     

Optical properties of GaAs

We have investigated the optical properties of gallium arsenide（GaAs） in the photon energy range 0.6- 6.0 eV.We obtained a refractive index which has a maximum value of 5.0 at a photon energy of 3.1 eV;an extinction coefficient which has a maximum value of 4.2 at a photon energy of 5.0 eV;the dielectric constant,the real part of the complex dielectric constant has a maximum value of 24 at a photon energy of 2.8 eV and the imaginary part of the complex dielectric constant has a maximum value of 26.0 at a photon energy of 4.8 eV;the transmittance which has a maximum value of 0.22 at a photon energy of 4.0 eV;the absorption coefficient which has a maximum value of 0.22×10⁸ m^-1 at a photon energy of 4.8 eV,the reflectance which has a maximum value of 0.68 at 5.2eV; the reflection coefficient which has a maximum value of 0.82 at a photon energy of 5.2 eV;the real part of optical conductivity has a maximum value of 14.2×10¹⁵ at 4.8 eV and the imaginary part of the optical conductivity has a maximum value of 6.8×10¹⁵ at 5.0 eV.The values obtained for the optical properties of GaAs are in good agreement with other results.     

A High‐Gain Microstrip Patch Array Antenna Using a Superstrate Layer

A dielectric superstrate layer above a microstrip patch antenna has remarkable effects on its gain and resonant characteristics. This paper experimentally investigates the effect of a superstrate layer for high gain on microstrip patch antennas. We measured the gain of antennas with and without a superstrate and found that the gain of a single patch with a superstrate was enhanced by about 4 dBi over the one without a superstrate at 12 GHz. The impedance bandwidths of a single patch with and without a superstrate for VSWR < 2 were above 11%. The designed 2×8 array antenna using a superstrate had a high gain of over 22.5 dB and a wide impedance bandwidth of over 17%.     

Design of a high-order single-loop ∑△ ADC followed by a decimator in 0.18 μm CMOS technology

This work presents an oversampled high-order single-loop single-bit sigma-delta analog-to-digital con verter followed by a multi-stage decimation filter. Design details and measurement results for the whole chip are presented for a TSMC 0.18 μm CMOS implementation to achieve virtually ideal 16-b performance over a baseband of 640 kHz. The modulator in this work is a fully differential circuit that operates from a single 1.8 V power supply. With an oversampling ratio of 64 and a clock rate of 81.92 MHz, the modulator achieves a 94 dB dynamic range. The decimator achieves a pass-band ripple of less than 0.01 dB, a stop-band attenuation of 80 dB and a transition band from 640 to 740 kHz. The whole chip consumes only 56 mW for a 1.28 MHz output rate and occupies a die area of 1×2 mm~2.