《计算机专业英语》部分文章翻译

Communication channels are an essential element of every communication system. These channels actually carry the data from one computer to another. There are two categories of communication channels. One category connects sending and receiving devices by providing a physical connection such as a wire or cable. The other category is wireless.

通信管道对于每一个通信系统来说是一个至关重要的元素。这些管道实际上把数据从一台计算机传输到另一台。有两个类别的通信管道。一类是有线，另一类是无线。

PHYSICAL CONNECTIONS

Physical connections use a solid medium to connect sending and receiving devices. These connections include telephone lines (twisted pair), coaxial cable,and fiber-optic cable.

物理连接使用固体介质连接、发送和接收设备。这些连接包括电话线路(双绞线)、同轴电缆和光纤电缆。

Telephone lines you see strung on poles consist of twisted-pair cable,which is made up of hundreds of copper wires. A single twisted pair culminates in a wall jack into which you can plug your phone and computer. (See Figure 9-3.) Telephone lines have been the standard transmission medium for years for both voice and data. However, they are now being phased out by more technically advanced and reliable media.Coaxial cable, a high-frequency transmission cable, replaces the multiple wires of telephone lines with a single solid-copper core. (See Figure 9-4.) In terms of the number of telephone connections, a coaxial cable has over 80 times the transmission capacity of twisted pair.Coaxial cable is used to deliver television signals as well as to connect computers in a network..

你所看到的电话线，是由上百根铜线缠绕而成的双绞线。双绞线的一个端口是固定电话,当然也可以插在手机和电脑上。电话线作为一个标准传输媒介，多年一来一直在负责语音和数据的传输。然而,他们现在已经被更先进、可靠的媒体所淘汰了。同轴电缆、高频传输电缆,取代了多个连接的电话线。在传输能力方面,一个同轴电缆是双绞线传输容量的80倍。同轴电缆先主要用于提供电视信号以及连接网络的电脑. .

Fiber-optic cable transmits data as pulses of light through tiny tubes of glass. (See Figure 9-5.) In terms of the number of telephone connections,fiber-optic cable has over 26,000 times the transmission capacity of twisted-pair cable. Compared to coaxial cable, they are lighter and more reliable at transmitting data. They transmit information using beams of light at light speeds instead of pulses of electricity, making them far faster than copper cable. Fiber-optic cable is rapidly replacing twisted-pair cable telephone lines.

光纤电缆传输数据是由光脉冲在细小的玻璃导管内进行的。(参见图9 - 5)。在传输能力上，光纤电缆的传输速度已经超过双绞线26000倍。与同轴电缆相比,光纤更轻，传输更快。光纤使用光束传输信息，而不是的电脉冲,这使他们传输速度远远快于铜电缆。光纤电缆正在迅速取代电缆电话线路。

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WIRELESS CONNECTIONS

Wireless connections do not use a solid substance to connect sending and receiving devices.Rather, they use the air itself. Primary technologies used for wireless connections are infrared, broadcast radio, microwave, and satellite.

无线连接不使用固体物质连接发送和接收数据。相反,他们使用空气本身传播。目前此项技术主要用于红外连接、广播无线电、微波和卫星。

Infrared uses infrared light waves to communicate over short distances.It is sometimes referred to as line-of-sight communication because the light waves can only travel in a straight line. This requires that sending and receiving devices must be in clear view of one another without any obstructions blocking that view.One of the most common applications is to transfer data and information from a portable device such as a notebook computer or PDA to a desktop computer.

红外技术使用红外光波在短距离通信。它有时被称为视距通信，因为光只能沿直线传播。这就要求发送和接收设备必须没有任何障碍物阻止。最常见的应用是用来传送数据和信息从一个便携式设备，如笔记本电脑或掌上电脑桌面计算机上传输数据。

Broadcast radio uses radio signals to communicate with wireless devices.For example, cellular telephones and many Web-enabled devices use broadcast radio to place telephone calls and/or to connect to the Internet. Some end users connect their notebook or handheld computers to a cellular telephone to access the Web from remote locations. Most of these Web-enabled devices follow a standard known as Wi-FI (wireless fidelity). This wireless standard is widely used to connect computers to each other and to the Internet.

广播电台使用无线电信号与无线设备。例如,移动电话和许多网络设备使用广播电台将电话和/或连接到互联网。一些终端用户连接他们的笔记本通过无线信号连接上网。大多数的这些网络设备遵循一个标准，称为wi - fi。这个无线标准被广泛用于局域网和因特网。

Microwave communication uses high-frequency radio waves. Like infrared, microwave communication provides line-of-sight communication because microwaves travel in a straight line. Because the waves cannot bend with the curvature of the earth, they can be transmitted only over relatively short distances. Thus, microwave is a good medium for sending data between buildings in a city or on a large college campus. For longer distances, the waves must be relayed by means of microwave stations with microwave dishes or antennas. (See Figure 9-6.) These stations can be installed on towers. high buildings. and mountaintoos.

微波通信使用高频无线电波。如红外、微波通信只能提供短距通信因为微波以直线的方式行进。因此,微波是非常适合用来在大城市或者校园内作为数据传输的媒介。微波发射台可以安装在塔或者高的建筑之上。

Bluetooth is a short-range wireless communication standard that uses microwaves to transmit data over short distances of up to approximately 33 feet. Unlike traditional microwaves,Bluetooth does not require line-of-sight communication. Rather, it uses radio waves that can pass through nearby walls and other nonmetal barriers. It is anticipated that within the next few years, this technology will be widely used to connect a variety of different communication devices.

蓝牙是一种短距离的无线通信标准,通信距离大约33英尺。与传统的微波相比,蓝牙不需要视距通信。相反,它使用无线电波可以穿透附近的墙壁和其他非金属壁垒。在未来几年中,这种技术将被广泛用于连接各种不同的通信设备。