数据通信 Communicating with Data(中文3900字,英文2200字)
数据信号在各种各样的话路上传输：它们通过导线从一根电杆传到另一根电杆；它们经过地下电缆传送；它们通过微波设备从一个山头传到另一个山头；它们通过海底电缆，通过通信卫星，从一个洲传到另一个洲。为了把数字化机器信号变换为适合在这些设备中传输的信号形式,需要使用某种类型的数据变换设备。
向变换设备发送部分（即调制器）提供输入的数据设备可以是键盘、打印机、卡片阅读器、纸带终端计算机或磁带终端机。变换器接收部分（即解调器）的输出可以适用于纸带凿孔机、打印机、卡片凿孔机、磁带机、计算机或视频显示终端。一般地说，变换器的调制部分和解调部分合并成为一个双向数据发送接收机，通常称之为数据调制解调器或数据传输机。
英文资料及中文翻译
Communicating with Data
Data signals are transmitted over various types of telephone circuits. They travel on wire from telephone pole to telephone pole, through underground cables, from mountain top to mountain top over microwave facilities, on the ocean floor in submarine cables, and via communications satellites from continent to continent. Some type of data conversion equipment is required to change the digital machine signals to a form suitable for transmission over these facilities.
The data machine which provides an input to the transmit section of the conversion equipment, or modulator ,can be a keyboard , printer, card reader, paper tape terminal computer or magnetic tape terminal. The output from the receive section of the converter, or demodulator, can be applied to a tape punch, printer, card punch, magnetic tape unit, computer, or visual display terminal. Typically, both the modulator and demodulator sections of the converter are combined into a two-way data transmitter-receiver, commonly called a data modem or data set. |
