1.PCM原理
抽样量化与编码:sampling,quantizing and coding
话路:speech channel幅值: amplitude value
抽样频率: sampling frequency
抽样速率: sampling rate脉冲流: stream of pulses
重复率: repetition rate 编码过程: coding process  
模拟信号: analog signal
传输质量: transmission quality
数字通信: digital communication
数字传输: digital transmission
含噪声的环境: noisy environment
传输路由: transmission path
信噪比 :signal-to-noise ratio
信号电平 :signal levels噪声功率: noise power
地面系统: terrestrial system
二进制传输: binary transmission
反向操作: reverse operation
8-位码序列: 8-digit sequence
接受端: receiving terminal 帧格式 :frame format
同步字 :synchronization word
实现这三项功能的方案 :the schemes for performing these three functions
一串幅值: a series of amplitude values
电话质量的话路 a speech channel of telephone quality
一个8位二进制码的序列: a sequence of 8-binary digits
理论上的最小抽样频率 :a minimum theoretical sampling frequency
占据着300Hz到3.4kHz频率范围的话路: a voice channel occupying the range 300Hz to 3.4kHz
每个样值8-位码: 8-digits per sample value
汽车点火系统的打火: the sparking of a car ignition system
重复率为64kHz的脉冲流: the stream of the pulses with a repetition rate of 64kHz
真实信号与噪声信号的关系: relationship of the true signal to the noise signal
由卫星上接受到的信号 :the signal received from a satellite
一条特定消息中的全部信息 :the complete informatian about a particular message
被传信号的波形 :the shape of the transmitted signal
由传输路由引入的衰减: the attenuation introduced by transmission path
将抽样的幅值转换成一串脉冲的单元 :the unit that converts sampled amplitude value to a set of pulses
涉及到第一路，第二路及其他各路的序列: a sequence relating to channel 1,2 and so on
被称为同步字的独特码序列: a unique sequence of pulses called synchronization word
地面系统 :terrestrial system
脉冲的“有”或“无” : the presence or absence of the pulses
高速的电子开关: a high-speed electronic switch
时分多路复用器 :the time division multiplexer
时分多路复用 :Time Division Multiplexer
2.异步串行数据传输
串行接口 serial interface
显示终端 CRT terminal
发送器与接收器 transmitter and receiver
数据传输 data transmission
数据流 data stream
闲置状态 the idle state
传号电平 mark level
空号电位 space level
起始位 start bit
停止位 stop bit
T秒的持续时间 duration of T seconds
奇偶校检位 parity bit
错误标志 error flag
传输错误 transmission error
下降沿 fallinf edge
符号间的空格 intersymbol space
接收机的定时 receiver timing
本地时钟 local clock
磁带 magnetic tape
控制比特 control bit
逻辑1电平 logical 1 level
二进制数据 binary data
明显的缺点 obvious disadvantage
异步串行数据传输 asynchronous serial data transmission
最为流行的串行接口 the most popular serial interface
所传送的数据 the transmitted data
发送器与接收器的时钟 the clocks at the transmitter and receiver
电传机的时代 the era of teleprinter
一个字符的点和划 the dots and dashs of a character
符号间空格持续时间的三倍 three times the duration of intersymbol space
被称为字符的比特组 the group of bits called characters
由7或8个比特的信息组成的固定单元 the invariable units comprising 7 or 8 bits of information
由接收机本地产生的时钟 a clock generated locally by the receiver
在字符后所收到的奇偶校检位 the received parity bit following the character
起始位的下降沿 the falling edge of the start bit
数据链路面向字符的特性 the character-oriented nature of the data link
3.数据通信
地下电缆 underground cable
通信卫星 communication satellite
微波设备 microwave facilities
调制器与解调器 modulator and demodulator
缓冲器 buffer
定时信号 timing signals
同步脉冲 synchronization pulses
时隙 time slot  
移位寄存器 shift register
传输媒体 transmission medium
线形衰弱 linear attenuation
信息安全 information security
键盘 keyboard
数据终端 data terminals
某种类型的数据转换设备 some type of data conversion equipment
视频显示终端 visual display terminal
称为数据调制解调器的双向数据发送接收机 two-way data transmistter-receiver called a data modem
全双工的数据传输系统 full-duplex data trandmission system
由数据处理器的运算速率所决定的速率 the rate determined by the operating speed of the data processor
由接口部件来的定时信号 timing signals from the interface assembly
磁心存储器 magnetic core memories
线性衰减和时延特性 linear attenuation and delay characteristics
传输损伤 transmission impairments
语音中的冗余特性 the redundant nature of speech
在数据发送器中的编码过程 coding process in the data transmitter
二进制的不归零信号 binary nonreturn-to-zero signal  
4.互联网
网络资源：network resource
信息服务：information services
远程终端：remote terminals
互联的系统：interconnected systems
命令：command
电子邮件：electronic mail
主机：host
无线信道：wireless channels
搜索工具：searching tools
用户界面：user interface
存取：access
文本信息：textual messages
协议：protocol
超文本协议：hypertext protocol
分布在全世界的计算机的巨大网络：gaint network of computers located all over the world
主干系统：backbone system
全国范围的网络：nationwild network
电子会议：electronic conferences
实时对话：live conversation
最大的信息库the largest repository of the computers on the net
网络设备资源：network facilities resources
在网上的绝大多数计算机：the vast majority of the computer on the net
UNIX操作系统：the UNIX operating system
在因特网和你的PC机之间传送数据的方法：a way to move data between the internet and your PC
方便的搜索工具：the convenient searching tools
联网的超文本协议：the network hypertext protocol
5.光纤通信介绍
光纤通信:optical fiber communications
光源：light source
波长：wavelength
激光器：laser
色散：dispersion
传输介质：transmission medium
多模光纤：multi-mode fiber
长途干线：long-houl trunks
单模光纤：singer-mode fiber
带宽：bandwidth
带宽用户：wideband subscriber
纤维光学：fiber-optics
商用技术：commercial technologe
门限电流：threshod current
光检测器：photodetector
波分复用：wavelength multiplexing
纤维光网络：fiber-optic network
视频带宽：video bandwidth
长途传输：long distance transmission
中继距离：repeater spacing
已装光纤的总长度：the total length of installed fiber
长途通信系统：long-haul telecommunication system
低衰减的石英纤维：the low-loss silica fiber
衰减接近瑞利极限的光纤：fibers with losses approaching the Rayleigh limit
室温下的门限电流：room temperature threshold currents
较长波长区：the longer wavelength region
用户接入工程：subscriber access project
部件性能和可靠性的改进：improvements in component performance and reliability
已安装的光纤系统的数据速率：data rates for installed fibre optic system
每秒吉比特：gigabit per second range
波分复用：wavelength multiplexing
带宽用户环路系统：widebend subscriber loop system
多纤连接器：multifibre connectors
设计寿命：projected lifetime
光源：light source
单模光纤：single-mode fibre
分布反馈式激光器：distributed-feedback laser
信息容量：information capacity
交换体系：switching hierarchy
带宽业务：broadband services