选择特殊符号
选择搜索类型
请输入搜索
目前光纤通信系统中常用的光源主要有两种:发光二极管(LED)和激光器(LD)。激光器由于在调制速率和耦合效率方面都明显优于发光二极管所以一般适用于大、中容量的长距离通信系统,同时由于电流—光输出特性线...
FAS系统,是基于GSM-R技术的新一代数字通信调度系统,具有适应铁路运输特点,符合铁路通信信号一体化技术发展趋势,技术水平高,应用范围广的综合竞争优势,在京津、武广和郑西客运三条高速铁路已得到成功应...
是的。
视讯通信系统工程试运行方案
视讯通信系统工程 试运行方案 第 1 页 XXXX视讯通信系统工程(以下简称系统)已全面完成,并于 2012年 1月 9 日通过部门初步验收。按照合同,系统将进入全面试运行阶段,以检验系统长 期运行的稳定性、可靠性和实际应用的效果。并在试运行中,建立健全运行操 作和系统维护规范以及应急预案,为系统投入实际运行和完善提供实际运行数 据和依据。 试运行主要包括:系统功能试运行;硬件设备的试运行;以及光纤、装修 的试运行。 一、试运行目的 试运行目的通过既定时间段的试运行,全面考察项目建设成果,并通过试 运行发现项目存在的问题,从而进一步完善项目建设内容,确保项目顺利通过 竣工验收并平稳地移交给运行管理部门。 通过实际运行中系统功能与性能的全面考核,来检验系统在长期运行中的 整体稳定性和可靠性。 1.系统功能、性能与稳定性考核 (1)系统功能及性能的实际应用考核; (2)系统主要硬件设备、辅助设
通信系统工程施工现场配合与控制
x 通信系统工程施工现场配合与控制 现代通信包括多媒体通信、 计算机通信网络、 个人通信、 数字图像通信 (可视电话) 、 移动卫星通信、 程控交换机、语音信箱与电子信箱等。在我国,电话网是通信的最基本的载 体,它的自动化将体现在硬件结构上和软件设计上,如可编程、可交换、可自动计费,并组 成全球性的网络系统等。电话通信线路从进户管线直到用户出线盒等组成,分别叙述如下: (1)通信电线引入(进户):通过电缆管沟或直埋从地下进户;通过电缆管沟或 直埋,由外墙进户;通过架空电缆由外墙进户。 (2)程控交换机房或配线设备间: 1)通信电缆引进屋内设置用户程控机时, 采用总配线箱或总配线架, 此房间称电 话机房。 2)通信电缆引进屋内不设置用户程控机时, 电话局进户电缆置于交接箱内, 此房 间称电话交接间。 3)电话机房或交接间宜设置在一层或二层,如有地下室,且较干燥,通风良好, 可考虑将电话机房或
《通信系统工程(第2版改编版)》内容:The objective of this book is to provide an introduction to the basic princi ples in the analysis and design of communication systems. It is primarily intended for use as a text for a first course in communications, either at a senior level or at a firstyear graduate level.BROAD TOPICAL COVERAGE Although we have placed a very strong emphasis on digital communications, we have provided a solid introduction to analog communications. The major topics covered are: An introduction to analog signal transmission and reception (Chapters 2and3)An introduction to digital communications (Chapters 48)EMPHASIS ON DIGITAL COMMUNICATIONS Our motivation for emphasizing digital communications is due to the techno logical developments that have occurred during the past five decades. To day, digital communication systems are in common use and generally carry the bulk of our daily information transmission through a variety of communi cations media, such as wireline telephone channels, microwave radio, fiber optic channels, and satellite channels.
PREFACE
1 INTRODUCTION
1. 1 Historical Review 1
1.2 Elements of an Electrical Communication System
1.2.1 Digital Communication System 9
1.2.2 Early Work in Digital Communications 13
1.3 Communication Channels and Their Characteristics
1.4 Mathematical Models for Communication Channels
1.5 Organization of the Book 28
1.6 Further Reading 30
2 ANALOG SIGNAL TRANSMISSION AND RECEPTION
2.1 Introduction to Modulation 32
2.2 Amplitude Modulation (AM) 33
2.2.1 Double-Sideband Suppressed Carrier AM 33
2. 2. 2 Conventional Amplitude Modulation 40
2.2.3 Single-Sideband AM 44
* 2.2.4 Vestigial-Sideband AM 48
2.2.5 Implementation of AM Modulators and Demodulators 52
2.2.6 Signal Multiplexing 58
2.3 Angle Modulation 61
2.3. 1 Representation of FM and PM Signals 62
2.3.2 Spectral Characteristics of Angle-Modulated Signals 66
2.3. 3 Implementation of Angle Modulators and Demodulators 73
2.4 Radio and Television Broadcasting 81
2.4.1 AM Radio Broadcasting 82
2.4. 2 FM Radio Broadcasting 84
2.4.3 Television Broadcasting 87
2.5 Mobile Radio Systems 97
2.6 Further Reading 100
Problems 100
3 EFFECT OF NOISE ON ANALOG COMMUNICATION SYSTEMS 115
3.1 Effect of Noise on Linear-Modulation Systems 115
3.1.1 Effect of Noise on a Baseband System 116
3. 1.2 Effect of Noise on DSB-SC AM 116
3. 1.3 Effect of Noise on SSB AM 118
3.1.4 Effect of Noise on Conventional AM 119
*3.2 Carrier-Phase Estimation with a Phase-Locked Loop (PLL) 124
3.2. 1 The Phase-Locked Loop ( PLL ) 125
3.2.2 Effect of Additive Noise on Phase Estimation 128
3.3 Effect of Noise on Angle Modulation 135
3.3. 1 Threshold Effect in Angle Modulation 145
3.3.2 Pre-emphasis and De-emphasis Filtering 149
3.4 Comparison of Analog-Modulation Systems 153
3.5 Further Reading 154
Problems 155
4 INFORMATION SOURCES AND SOURCE CODING 161
4.1 Modeling of Information Sources 162
4. 1.1 Measure of Information 164
4.1.2 Joint and Conditional Entropy 167
4.2 Source-Coding Theorem 169
4.3 Source-Coding Algorithms 172
4.4 Rate-Distortion Theory 177
4. 4. 1 Mutual Information 178
4. 4. 2 Differential Entropy 179
4.4.3 Rate-Distortion Function 181
4.5 Quantization 187
4.5. 1 Scalar Quantization 188
* 4.5.2 Vector Quantization 198
4.6 Waveform Coding 201
4.6. 1 Pulse-Code Modulation ( PCM) 201
4. 6. 2 Differential Pulse-Code Modulation ( DPCM) 207
4.6. 3 Delta Modulation (AM) 210
4.7 Digital Audio Transmission and Digital Audio Recording 213
4. 7. 1 Digital Audio in Telephone Transmission Systems 214
* 4. 7. 2 Digital Audio Recording 216
4.8 Further Reading 221
Problems 222
5 DIGITAL TRANSMISSION THROUGH THE ADDITIVE WHITE GAUSSIAN NOISE CHANNEL
6 DIGITAL TRANSMISSION THROUGH BANDLIMITED AWGN CHANNELS
7 CHANNEL CAPACITY AND CODING
8 WIRELESS COMMUNICATIONS
REFERENCES
INDES2100433B
2021年,通信系统工程安装与维护列入《职业教育专业目录(2021年)》。