首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Telecommunications stand for devices and systems that transmit electronic or optical signals across long distances. Telecommunic
Telecommunications stand for devices and systems that transmit electronic or optical signals across long distances. Telecommunic
admin
2011-01-02
72
问题
Telecommunications stand for devices and systems that transmit electronic or optical signals across long distances. Telecommunications enables 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. Telecommunications enables people to sand and receive personal messages across town, between countries, and to and from outer space. It also provides the key medium for delivering news, data, information, and entertainment.
Telecommunications devices convert different types of information, such as sound and video, into electronic or optical signals. Electronic signals typically travel along a medium such as copper wire or are carried over the air as radio waves. Optical signals typically travel along a medium such as strands of glass fibers. When a signal reaches its destination, the device on the receiving end converts the 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.
Telecommunications messages can be sent in a variety of ways and by a wide range of devices. The messages can be seat from one sender to a single receiver (point-to-point) or from one sender to many receivers (point-to-multipoint). Personal communications, such as a telephone conversation between two people or a facsimile (fax) message (see Facsimile Transmission), usually involve point-to-point transmission. Point-to-multipoint telecommunications, often called broadcasts, provide the basis for commercial radio and television programming.
Telecommunications begin with messages that are converted into electronic or optical signals. Some signals, such as those that carry voice or music, are created in an analog or wave format, but may be converted into a digital or mathematical format for faster and more efficient transmission. 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.
Individual people, businesses, and governments use many different types of telecommunications systems. Some systems, such as the telephone system, use a network of cables, wires, and switching stations for point-to-point communication. Other systems, such as radio and television, broadcast radio signals over the air that can be received by anyone who has a device to receive them. Some systems make use of several types of media to complete a transmission. For example, a telephone call may travel by means of copper wire, fiber-optic cable, and radio waves as the call is sent from sender to receiver. All telecommunications systems are constantly evolving as telecommunications technology improves. Many recent improvements, for example, offer high-speed broadband connections that are needed to send multimedia information over the Internet.
Personal computers have pushed the limits of the telephone system as more and more complex computer messages are being sent over telephone lines, and at rapidly increasing speeds. This need for speed has encouraged the development of digital transmission technology. The growing use of personal computers for telecommunications has increased the need for innovations in fiber-optic technology.
Telecommunications and information technologies are merging and converging. This means that many of the devices now associated with only one function may evolve into more versatile equipment. This convergence is already happening in various fields. Some telephones and pagers are able to store not only phone numbers but also names and personal information about callers. Wireless phones with keyboards and small screens can access the Internet and send and receive e-mail messages. Personal computers can now access information and video entertainment and are in effect becoming a combined television set and computer terminal. Television sets can access the Internet through add-on appliances. Future modifications and technology innovations may blur the distinctions between appliances even more.
Convergence of telecommunications technologies may also trigger a change in the kind of content available. Both television and personal computers are likely to incorporate new multimedia, interactive, and digital features. However, in the near term, before the actualization of a fully digital telecommunications world, devices such as modems will still be necessary to provide an essential link between the old analog world and the upcoming digital one.
According to the passage, ______ has become the driving force for the development of telephone system?
选项
A、information technologies
B、Internet
C、PC
D、convergence of telecommunications technologies
答案
C
解析
转载请注明原文地址:https://kaotiyun.com/show/TJeO777K
0
专业英语八级
相关试题推荐
Incontrasttotraditionalanalysesofminoritybusiness,thesociologicalanalysiscontendsthatminoritybusinessownershipi
Extraordinarycreativeactivityhasbeencharacterizedasrevolutionary,flyinginthefaceofwhatisestablishedandproducing
I’vecometotheSanJoseofficeparkwhereeBayishousedtonosearoundandfigureoutwhatmakesthisbusinessapparentlyim
Videoconferencingisgraduallybecominganacceptedmeansinwhichtodobusiness.Foralongtimeissufferedfromtheimageo
Whenscientistsfirstwarnedinthe1970sthatCFCscouldattackozone,theU.S.respondedbybanningtheiruseinspraycans.B
SuccessPersonalityAccordingtoaGallupsurvey,anumberofqualitiesarecommonamongsuccessfulpeople.Herearefiveof
ThirtyyearsagoIturnedonourfamily’sblack-and-whiteconsoleTVtowatchanorchestraconductornearlyashyperactiveasI
Morethanjustarevolutionarytoolforindexing,analyzing,ortransmittingcontent,digitaltechnologyisactuallyreshapingt
B英国文学之作家作品。GeorgeBernardShaw(肖伯纳)是英国现代著名的戏剧家,其代表作为Pygmalion(《皮革玛丽翁》,又名《卖花女》)。
随机试题
已知森林F={T1,T2,T3,T4,T5),各棵树Ti(i=1,2,3,4,5)中所含结点的个数分别为7,3,5,1,2,则与F对应二叉树的右子树中的结点个数为()
A.阑尾壁有纤维组织增生B.阑尾黏膜上皮非典型增生C.阑尾壁内炎细胞浸润,各层均见出血、坏死D.黏膜层和黏膜下层充血、水肿,较多中性粒细胞浸润E.阑尾全层弥漫性中性粒细胞浸润慢性阑尾炎
后天性小口畸形最常见的原因是()
儿童期重要心理特点
卡介苗是
根据《小型水电站施工技术规范》(SL172—96),小型水电站施工中,钢管四周锚筋埋设孔内的砂浆应具有()以上的强度。
在企业财务统计中,( )不属于长期投资的统计内容。
工商行政管理机关行政行为一旦合法成立,就发生一定的法律效力,其不具备的效力是()。
甲男(15岁)与乙女(13岁)在同一所中学上学,二人在参加校文体活动时相识并成为好友,关系日渐密切。某日二人在公园发生性关系时被发现。据甲交待,二人还曾在自己家中发生过一次性关系。甲、乙均表示是双方自愿。乙的家长要求追究甲的刑事责任。经调查二人确属自愿且未
从15个人中选择5个人,且有3个人不能同时选择,问有多少种选择方法?
最新回复
(
0
)