数字微波通信综合测试系统

数字微波通信综合测试仪是将十几台仪器的测试功能集成在一个测试系统中。它可以对数字微波通信系统的大部分参量进行测量 ,特别适合于数字微波移动通信系统的测量。本文简要介绍了数字微波通信综合测试仪的原理和应用。     

数字指纹及其在版权保护中的应用

将数字指纹应用于版权保护领域的研究,日益成为国际上非常活跃的研究方向.本文首先在分析数字指纹的功能与特征的基础上,提出了数字指纹系统的数学模型,将其具体应用于版权保护,具有较好的效果,然后分析了数字指纹存在的攻击、编码方案以及指纹协议发展,最后探讨了数字指纹在版权保护中的应用及前景.     

VHDL语言在电子设计实践中的应用

随着ASIC和计算机技术的不断发展，借助HDL完成硬件设计已成为电子设计领域的迫切需求。介绍了一种硬件描述语言，即VHDL语言的功能特点以及设计数字逻辑电路和数字系统的新方法，并以设计实例的形式，进一步分析并探讨了将其应用于电子设计自动化(EDA)实验中的优越性。     

液体冲压发动机数字电子控制系统

为某型号整体式液体冲压发动机设计了数字电子－液压机械控制系统，介绍了该系统的控制方案、工作原理和工作方式。数字电子－液压机械控制系统和冲压发动机与弹体数字仿真器等组成液体冲压发动机、弹体／发动机控制系统半实物仿真系统，对数字电子－液压机械控制系统的功能及工作协调性进行了检验，半实物仿真试验结果证明，该系统满足设计要求。     

π/4 D-QPSK基带调制解调的DSP实现

在以前的数字蜂窝系统中，往往采用FSK、ASK、PSK等调制方式。随着数字蜂窝系统的发展，对调制和数字蜂窝系统的技术要求也越来越高了。利用DSP手段，实现的π／4D—QPSK基带调制解调在技术要求方面要优于FSK、ASK、PSK等调制方式，更能满足数字蜂窝系统的要求。该技术的实现，提高了调制与解调的速度，为数字蜂窝系统的发展提供了更大的发展空间。     

数字孪生及其在航空航天中的应用

数字孪生已引起国内外的广泛重视，可看作是连接物理世界和数字世界的纽带。其通过建立物理系统的数字模型、实时监测系统状态并驱动模型动态更新实现系统行为更准确的描述与预报，从而在线优化决策与反馈控制。本文分析表明数字孪生体相比一般的模拟模型，具有集中性、动态性和完整性的突出特点。数字孪生的发展需要复杂系统建模、传感与监测、大数据、动态数据驱动分析与决策和数字孪生软件平台技术的支撑。在航空航天领域，数字孪生可应用于飞行器的设计研发、制造装配和运行维护。重点讨论了应用机身数字孪生进行寿命预测与维护决策的案例，相比于周期性维护，具有检修次数更少、维护成本更低的优势。最后，给出了数字孪生在空间站、可重复使用飞船的地面伴飞系统中的初步应用框架。     

HZG—B环氧真空灌注机温度控制系统

本控制柜是对HZG－B环氧真空灌注机的19个部件进行温度及加热功率调节的自动控制系统。它采用自动巡检的方式，不断地对系统各加温，保温点的加热，检测等部件进行数据采集。处理和控制，温度检测采用了稳定性很高的TP100铂热电阻，保证了系统长期工作的稳定性和可靠性；可控硅作为加热部件的功率切换，提高了转换点的可靠性，消除了系统工作噪声，过零触发技术的应用有效地降低了本系统对电网及空间的射频辐射。另外，该系统还具有较完善的保护功能，一旦某点出现超温而未得到及时处理时，系统将切断整机电源，防止将灌注机损坏，影响企业的正常生产。为了提高可靠性和抗干扰性，系统采用数字量低电平的有效工作方式，对各功能部件进行控制，它较之前期的系统无论是在控制精度，工作可靠性，还是在使用操作，日常维护等方面都有较大的改善。     

液体冲压发动机数字电子控制系统换

为某型号整体式液体冲压发动机设计了数字电子-液压机械控制系统,介绍了该系统的控制方案、工作原理和工作方式.数字电子-液压机械控制系统和冲压发动机与弹体数字仿真器等组成液体冲压发动机、弹体/发动机控制系统半实物仿真系统,对数字电子-液压机械控制系统的功能及工作协调性进行了检验.半实物仿真试验结果证明,该系统满足设计要求.     

基于SHEPWM与谐波补偿技术的混合逆变策略

文章介绍了谐波补偿器的结构特点及工作原理,研究论证了SHEPWM技术应用于三相逆变系统消除指定谐波的有效性。将SHEPWM与谐波补偿技术结合应用于逆变系统展开研究,充分拓展了谐波补偿器的应用价值,利用了SHEPWM技术可应用于大功率场合的优点。分析了混合逆变系统的工作原理,介绍了其电路结构,推导并建立了逆变系统数学模型,仿真验证了混合逆变策略的可行性,特别是在抑制特定低次谐波方面效果显著。     

ARINC629数字总线传输系统

ＡＲＩＮＣ６２９数字总线传输系统已于波音７７７飞机，是目前飞机上最为先进的数字信息传输系统。本文以对比的方式描述了ＡＲＩＮＣ６２９与４２９数字总线在结构上，传输特征及数据字构成方面的不同及ＡＲＩＮＣ６２９数字总线传输系统的先进性。     

串行MSK DS／SSMA系统性能分析

分析了串行MSK DS/SSMA系统的性能。这种单通道系统能够产生和并行双通道MSK DS/SSMA系统相同的发射信号,它具有恒包络和优良的频谱特性。而且,串行MSK DS/SSMA系统的硬件成本和BPSK DS/SSMA系统的相当,分析结果表明,前者的性能更优。     

Adaptive suppression of passive intermodulation in digital satellite transceivers

For the performance issues of satellite transceivers suffering passive intermodulation interference,a novel and effective digital suppression algorithm is presented in this paper.In con trast to analog approaches,digital passive intermodulation (PIM) suppression approaches can be easily reconfigured and therefore are highly attractive for future satellite communication systems.A simplified model of nonlinear distortion from passive microwave devices is established in consid eration of the memory effect.The multiple high-order PIM products falling into the receiving band can be described as a bilinear predictor function.A suppression algorithm based on a bilinear poly nomial decorrelated adaptive filter is proposed for baseband digital signal processing.In consideration of the time-varying characteristics of passive intermodulation,this algorithm can achieve the rapidness of online interference estimation and low complexity with less consumption of resources.Numerical simulation results show that the algorithm can effectively compensate the passive intermodulation interference,and achieve a high signal-to-interference ratio gain.     

高速TCM传输技术及其应用

首先讨论了传统数字传输体制的特点，找出传统调制与编码的分离独立设计是制约数字通信系统性能进一步提高的本质根源；并由此论述了编码与调制相结合的高速数字传输体制，重点讨论了网格编码调制(TCM)技术的基本特点、集合分割映射原理、性能估算，并对TCM在AWGN信道中的性能进行了仿真。     

High-speed avionic optical fiber CDMA networks

With applications of systems integration technology to advanced aircrafts, high-speed and high-capacity optical fiber communication networks should be employed to support airborne broadband communication services. To guarantee real-time multiuser communications over a network, the selection of medium-access schemes is critical for avionics applications. In this paper, we briefly discuss the issues on high-speed multiple-access techniques and their applicability. Then we focus on the design and operation aspects of avionic optical fiber code-division multiple access (CDMA) networks. Some practical considerations on implementing such a CDMA network are also addressed and further improvement is pointed out. It is shown that avionic optical fiber CDMA networks can find a use in real-time avionic sensor data distribution, data exchange, and computer interconnects     

Cryptographic Digital Communication

This paper reviews the fundamentals of cryptographic digital systems and defines and discusses the two basic types of ciphers. The remainder of this article examines the word and bit error rates in digital al communication systems with block or stream ciphers. Upper bounds and ensemble averages of the error rates are obtained for both ciphers. The effect of modulation type on the degradation in communication system performance caused by the addition of cryptography is analyzed. A comparison is made between block and stream ciphers with respect to their effects on degradation.     

Space-time adaptive processing and adaptive arrays: specialcollection of papers

Space-time adaptive processing (STAP) and related adaptive array techniques hold tremendous potential for improving sensor performance by exploiting signal diversity. Such methods have important application in radar, sonar, and communication systems. Recent advances in digital signal processing technology now provide the computational means to field STAP-based systems. The objective of this special collection of papers is to examine the current state-of-the art in STAP technology and explore the remaining obstacles, practical issues and novel techniques required to implement STAP-based radar, sonar or communication systems     

IS-95 CDMA系统RAKE接收机仿真

RAKE接收机作为一种有效的抗多径技术，充分利用了经过各条路经到达的信号能量获得分集增益。分别对IS—95码分多址标准CDMA系统进行了简单介绍，对RAKE接收机的工作原理和SystemView软件进行了介绍，概述了IS—95RAKE接收机的基本特点和性能参数，给出了采用SystemView软件仿真IS—95码分多址标准RAKE接收机的方法和仿真结果。仿真表明，利用RAKE接收机具有信道估计算法简单、信道跟踪实时性强的特点。     

Modeling and Performance Evaluation of Nonlinear Satellite Links-A Volterra Series Approach

An analytical solution to the problem of modeling bandpass nonlinear channels and evaluating the performance of digital communication systems operating on them is presented. A method based on a Volterra series representation of the overall channel is first proposed, which allows one to extend to nonlinearities with memory the well-known concepts of complex envelope of bandpass signals and low-pass equivalent of bandpass linear systems. The general results previously mentioned are then applied to digital satellite communication systems operating over nonlinear channels. The effect of a nonlinear amplifier located in the satellite is considered, in combination with that of transmitting and receiving filters located in the Earth stations. In addition, both uplink and downlink noise are taken into account. Basic advantages of this approach are the generality it offers to the analysis and the fact that it allows accurate evaluation of the error probability in a short computer time.     

Proposed airborne optical fiber asynchronous CDMA systems usingfully optical orthogonal codes for real-time avionic data distributionsand computer interconnects

We report the design of optical fiber asynchronous code-division multiple-access (CDMA) systems using fully optical orthogonal codes (FOOCs), which can be employed to support future airborne real-time communication services. The use of incoherent optical CDMA (IO-CDMA) can result in lower complexity and more reliable implementation than that of the coherent version, so this makes IO-CDMA more adequate for operation in the severe aircraft environment. When FOOCs are used in the IO-CDMA systems, the peaks of all the cross-correlation functions and all the sidelobes of any auto-correlation function are then limited to “1” (i.e., the minimum correlation constraint for incoherent optical processing) in fully asynchronous transmissions. Moreover, proposed systems can effectively support multi-rate and variable-rate data communications with no violation of the minimum correlation constraint and no change of IO-CDMA encoders/decoders. This characteristic can be used to improve the system flexibility and availability. A basic experiment is also demonstrated to verify the characteristics of FOOCs