Synchronization of chaotic solid-state Nd:YAG lasers: Application to secure communication

In this paper, the synchronization problem of coupled chaotic lasers in master–slave configuration is numerically studied. The approach used allows to give a simple design procedure for the slave laser. In particular, we consider a complex system composed by two chaotic Nd:YAG lasers coupled through the first state variable of the master laser. Synchronization of chaotic Nd:YAG lasers is achieved by injecting the chaotic signal from the master Nd:YAG laser into the slave Nd:YAG laser. The robustness of synchronization is discussed when a mismatch of parameters occurs, and the effects of the channel noise on recovered information are showed. A potential application of chaotic synchronization of Nd:YAG lasers to transmit encrypted digital information is also given.     

基于反馈调节的闪烁脉冲稀疏量化电平方法

PET探测器采用SQL采样电路对闪烁脉冲进行处理,可固定量化电平。零点噪声引起的电平翻转导致电压比较器长时间非正常发热,无法设置较低的量化电平,限制了探测器符合时间分辨率的提高。文中提出一种基于反馈调节的闪烁脉冲处理方法,该方法通过使用三极管饱和状态下的开关特性,对SQL量化样本进行反馈调节。利用延迟元件对量化样本进行延迟同步,产生可以随样本逻辑电平变化的量化电平,避免了零点噪声对SQL采样电路的影响。实验结果表明,在相等时间内,优化的SQL采样电路的采样量比原SQL采样电路的采样量减少了29%,符合时间分辨率提升了179.3 ps,有效减少了PET探测器无用功耗,提高了PET系统的符合时间分辨率。     

略谈通信网时频同步技术演进趋势

根据ITU-T近期发布的通信同步技术标准建议书，纵观电信运营商对于同步网发展所做的努力，分析国内外厂商和研究单位的代表性新产品，尝试探讨通信同步网和网同步的演进趋势，归纳其特点是：为了迎接5G移动通信等新挑战，通信网时频同步性能指标在明显提升，尤其是高精度时间同步受到更大的重视，需要采用新技术改变传统同步方式，需要研制和运用新的同步设备和检测仪表，新的同步技术标准也彰显了中国在国际的引领作用和影响。     

Nonclassical Attack on a Quantum Key Distribution System

The article is focused on research of an attack on the quantum key distribution system and proposes a countermeasure method. Particularly noteworthy is that this is not a classic attack on a quantum protocol. We describe an attack on the process of calibration. Results of the research show that quantum key distribution systems have vulnerabilities not only in the protocols, but also in other vital system components. The described type of attack does not affect the cryptographic strength of the received keys and does not point to the vulnerability of the quantum key distribution protocol. We also propose a method for autocompensating optical communication system development, which protects synchronization from unauthorized access. The proposed method is based on the use of sync pulses attenuated to a photon level in the process of detecting a time interval with a signal. The paper presents the results of experimental studies that show the discrepancies between the theoretical and real parameters of the system. The obtained data allow the length of the quantum channel to be calculated with high accuracy.     

一种卫星SCMA系统接收机同步算法

SCMA技术通过资源过载能够实现大规模用户的并发接入,非常适合物联网应用,但是SCMA解调性能受定时误差和载波频差影响较大。对此,文中通过基于导频的两阶段频差估计算法和ML相位偏差估计算法,实现大频差下的高精度频、相偏估计;通过SCMA和LDPC联合迭代,利用发送数据实现高精度定时误差估计。仿真结果表明,在AWGN信道下,载波同步算法采用优化的帧结构后可以获得距理想性能不到0.25dB的优异性能,定时同步算法在1次迭代下获得了距理想性能仅0.2dB的性能,在3次迭代下获得了与理想性能一致的优异性能,能适应大频差、高动态的卫星信道环境。     

运营商级SD-WAN组网NTP时钟同步方案

摘 要：SD-WAN 发展势头迅猛，电信运营商与互联网企业都在不断扩大布局。作为形态多样化的技术， SD-WAN 中并未对时钟同步做出明确规范。分析了时钟同步对 SD-WAN 技术实现和业务运行的重要性。简述了在SD-WAN被广泛采用的互联网公共NTP服务时钟同步方案的利弊，由此展开讨论在不同场景可实现的自建NTP服务时钟同步方案，并设计了基于自建NTP服务利用管理隧道加密传输NTP同步数据的时钟同步方法，使SD-WAN平台和设备在时间同步时获得更高的安全性与稳定性。     

A 4 GS/s 4 bit ADC with 3.8 GHz analog bandwidth in GaAs HBT technology

An ultra-wideband 4 GS/s 4 bit analog-to-digital converter(ADC)which is fabricated in 2-level interconnect, 1.4μm InGaP/GaAs HBT technology is presented.The ADC has a-3 dB analog bandwidth of 3.8 GHz and an effective resolution bandwidth(ERBW)of 2.6 GHz.The ADC adopts folding-interpolating architecture to minimize its size and complexity.A novel bit synchronization circuit is used in the coarse quantizer to eliminate the glitch codes of the ADC.The measurement results show that the chip achieves larger than 3.4 ENOBs with an input frequency band of DC-2.6 GHz and larger than 3.0 ENOBs within DC-4GHz at 4 GS/s.It has 3.49 ENOBs when increasing input power by 4 dB at 6.001 GHz of input.That indicates that the ADC has the ability of sampling signals from 1st to 3rd Nyquist zones(DC-6 GHz).The measured DNL and INL are both less than±0.15 LSB. The ADC consumes power of 1.98 W and occupies a total area of 1.45×1.45 mm~2.     

卫星共视技术在铁路同步网性能监测中的应用研究

介绍了卫星共视技术基本原理,并将卫星共视技术应用在铁路通信同步网性能监测当中,弥补了现有铁路同步网性能监测的不足。应用中发现了同步网网管设置错误并予以纠正,为维护人员提供了很好的监测手段。建议在铁路通信网中推广应用卫星共视监测技术。     

Synchronization of noise-perturbed optical systems with multiple time delays

The theories of intelligent information processing are urgently needed for the rapid development of modem science.In this paper,a novel fuzzy chaotic neural network,which is the combination of fuzzy logic system,artificial neural network system,and chaotic system,is proposed.We design its model structure which is based on the Sigmoid map,derive its mathematical model,and analyse its chaotic characteristics.Finally the relationship between the accuracy of map and the membership function is illustrated by simulation.