通信工程专业英语(本) Lesson 3 Modern Electronic Communication Systems 第3课 现代电子通信系统 邓 磊 denglei@dgut.edu.cn https://leideng.github.io/communication-english/ (Some pictures are from the Internet) 东莞理工学院 电子工程与智能化学院 2017.09.11

Outline Technical Contents Technical Terms Structures and Sentences Electronic Communication Systems 电子通信系统 The Global Telecommunications Network 全球电信网 Communication System Parameters 通信系统参数 Technical Terms Structures and Sentences

Technical Contents: Electronic Communication Systems Electronic communication system is an electronic system to transit a signal from one place to another place. The transmitter converts a signal into an electrical/electronic signal that can travel through the transmission medium (channel). The receiver converts the electrical/electronic signal back to its original form.

Technical Contents: Electronic Communication Systems Transmission medium (channel) 传输介质（信道） Guided: copper wire (wireline communication), optical fiber (optical communication) Unguided: free space (wireless/RF communication)

Technical Contents: The Global Telecommunications Network

Technical Contents: Communication System Parameters Bandwidth (BW): Different meanings in different contexts BW of a signal (unit: Hz): frequency range of a signal BW of a filter (unit: Hz): passband of the filter A channel can also be regarded as a filter E.g. The bandwidth of modern twist pairs could reach 250MHz BW of a channel (unit: bps): channel capacity E.g.: The bandwidth of modern twist pairs could reach 1Gbps.

Technical Contents: Communication System Parameters Broadband versus Baseband 宽带和基带

Technical Contents: Communication System Parameters Synchronous versus Asynchronous 同步和异步

Technical Contents: Communication System Parameters Simplex, Half-Duplex, and Full-Duplex 单工，半双工和全双工 Simplex Example: radio/TV broadcast Half-Duplex Example: telephone communication Full-Duplex Example: video conferencing

Technical Terms switch n. 交换机 central office 中心局 line card 线路卡 local loop/subscriber line 本地环/用户线 POTS abbr. plain old telephone service 普通老式电话业务

Technical Terms source n. 信源 destination n. 信宿 overhead n. 开销 sender 发送者 destination n. 信宿 sink n. 信宿 receiver 接收者 overhead n. 开销 acknowledgement (ACK) n. 应答；确认

Technical Terms optical fiber 光纤 coaxial [kəʊ'æksɪəl] cable 同轴电缆 twisted pair 双绞线

Technical Terms data synchronization 数据同步 error detection 错误检测 error correction 纠错 TV broadcast 电视广播 unicast 单播 multicast 多播 broadcast 广播 RF abbr. radiofrequency 射频

Technical Terms LAN abbr. local area network 局域网 WAN abbr. wide area network 广域网 Radar abbr. radio detection and ranging 雷达（无线电探测和测距）

Structures and Sentences Information can be defined as any physical pattern that is meaningful to both sender and receiver. 信息可定义为对发送方和接收方都有意义的物理模式。 Define vt. 定义 Definition n. 定义 We define A as B. 我们把A定义为B Everyone talks about big data, but no one knows the definition of big data.

Structures and Sentences The telephone itself, of course, is a system. It transforms the electrical signal that propagates down the twisted pair into a sound signal and transforms a local sound signal into an electrical signal that can propagate down the twisted pair. 当然，电话本身也是一个系统。它将传播到双绞线的电信号转换成声音信号，又将本地声音信号转换为可在双绞线上传播的电信号。

Structures and Sentences The framing for asynchronous communication is based on a single character, while that for synchronous communication is based on a much bigger block of data. 在异步通信中，组帧只需使用一个字符，然而在同步通信中，组帧需要一个大很多的数据块。

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