计算机英语专业外语第三版UNIT 7

UNIT 7 Computer CommunicationsSection A Telecommunications and ComputersTelecommunications allows people around the world to contact one another, to access information instantly, and to communicate from remote areas. Telecommunications usually involves a sender of information and one or more recipients linked by a technology, such as a telephone system, that transmits information from one place to another.电信使世界各地的人们得以互相联系，即刻获取信息，并在边远地区进行通信。

电信通常涉及一个信息发送者和一个或多个接收者，他们通过将信息从一地发送到另一地的技术联在一起，如电话系统。

Telecommunications devices convert different types of information, such as sound and video, into electronic signals. The signals can then be transmitted by means of media such as telephone wires or radio waves.电信设备将不同类型的信息，如声音和图像，转换成电子信号。

然后，这些信号就可以通过电话线或无线电波等媒介进行发送。

When a signal reaches its destination, the device on the receiving end converts the electronic signal back into an understandable message, such as sound over a telephone, moving images on a television, or words and pictures on a computer screen.信号到达其目的地后，接收端的设备将电子信号转换回可以理解的信息，如电话中的声音、电视上的活动图像或计算机屏幕上的文字和图片。

Telecommunications enables people to send and receive personal messages across town, between countries, and to and from outer space. It also provides the key medium for news, data, information and entertainment.电信使人们能够在城市不同之处、国家之间以及和外层空间之间发送和接收个人信息。

电信也为新闻、数据、信息和娱乐提供了关键的媒介。

Telecommunications messages can be sent in a variety of ways and by a wide range of devices. The messages can be sent from one sender to a single receiver (point-to-point) or from one sender to many receivers (point-to-multipoint).电信信息可通过各种方式和设备发送。

信息可由一个发送者发送给一个接收者（点对点），或者由一个发送者发送给多个接收者（点对多点）。

Personal communications, such as a telephone conversation between two people or a facsimile (fax) message, usually involve point-to-point transmission. Point-to-multipoint telecommunications, often called broadcasts, provide the basis for commercial radio and television programming.个人通信，如两个人之间的电话对话或传真信息，通常涉及点对点的传输。

点对多点的电信传输，通常称为广播，为商业广播和电视节目的播送提供了基础。

Telecommunications begin with messages that are converted into electronic signals. The signals are then sent over a medium to a receiver, where they are decoded back into a form that the person receiving the message can understand. There are a variety of ways to create and decode signals, and many different ways to transmit signals.电信以信息转换为电子信号为开端。

然后，这些信号通过媒介发送到接收机，并在这里解码，恢复为接收信息的人能够理解的形式。

有各种方法可以产生并解译信号，也有许多不同的方法传输信号。

Devices such as the telegraph and telephone relay messages by creating modulated electrical impulses, or impulses that change in a systematic way. These impulses are then sent by wires, radio waves, or other media to a receiver that decodes the modulation.电报机与电话机等设备，通过产生调制电脉冲或以系统化方式变化的脉冲，来传递信息。

接下来，这些脉冲通过导线、无线电波或其他媒介发送给接收机，并由其进行解调。

The telegraph, the earliest method of delivering telecommunications, works by converting the contacts (connections between two conductors that permit a flow of current) between a telegraph key and a metal conductor into electrical impulses.电报机这种最早的传递电信信息的方法，通过将电报机键与金属导体之间的接触（使电流得以流动的两个导体之间的连接）转换成电脉冲而进行工作。

These impulses are sent along a wire to a receiver, which converts the impulses into short and long bursts of sound or into dots and dashes on a simple printing device. Specific sequences of dots and dashes represent letters of the alphabet. In the early days of the telegraph, these sequences were decoded by telegraph operators.这些脉冲沿着导线发送到接收机，而接收机则将这些脉冲转换成长与短的声音脉冲串，或者在简单的打印设备上打印出来的点与划。

点与划的特定序列代表字母表中的字母。

在早期的电报中，这些序列由电报机操作员进行解译。

In this way, telegraph operators could transmit and receive letters that spelled words. Later versions of the telegraph could decipher letters and numbers automatically. Telegraphs have been largely replaced by other forms of telecommunications, such as fax machines and electronic mail (e-mail), but they are still used in some parts of the world to send messages.这样，电报机操作员就可以发送和接收拼成词语的字母。

后来的电报机能自动解译字母和数字。

电报机在很大程度上已被其他电信形式所取代，如传真机和电子邮件，但在世界有些地方，电报机仍然用来发送信息。

Telegraphs, telephones, radio, and television all work by modifying electronic signals, making the signals imitate, or reproduce, the original message. This form of transmission is known as analog transmission. Computers and other types of electronic equipment, however, transmit digital information.电报机、电话机、收音机和电视机都是通过修改电子信号，使其模拟或再现原来的信息，来进行工作的。

这种传输称为模拟传输。

然而，计算机和其他类型的电子设备是传输数字信号的。

Digital technologies convert a message into electronic form first by measuring different qualities of the message, such as the pitch and volume of a voice, many times. These measurements are then encoded into multiple series of binary numbers, or 1s and 0s.数字技术将信息转换成电子的形式。