tailieunhanh - Mạng và viễn thông P1

Znformation and its Lonveyance The world about us brims with information. the time our ears, All eyes, fingers, mouths and noses sense theenvironmentaround us, continuallyincreasing our ‘awareness’,‘intelligence’ and ‘instructive knowledge’. Indeed these last two phrases are the heart of the Oxford Dictionary’s at definition of thewordinformation. | Networks and Telecommunications Design and Operation Second Edition. Martin P. Clark Copyright 1991 1997 John Wiley Sons Ltd ISBNs 0-471-97346-7 Hardback 0-470-84158-3 Electronic PART 1 FUNDAMENTALS OF TELECOMMUNICATIONS NETWORKS Networks and Telecommunications Design and Operation Second Edition. Martin P. Clark Copyright 1991 1997 John Wiley Sons Ltd ISBNs 0-471-97346-7 Hardback 0-470-84158-3 Electronic Information and its Conveyance The world about us brims with information. All the time our ears eyes fingers mouths and noses sense the environment around us continually increasing our awareness intelligence and instructive knowledge . Indeed these last two phrases are at the heart of the Oxford Dictionary s definition of the word information. Communication on the other hand is defined as the imparting conveyance or exchange of ideas knowledge or information . It might be done by word image instruction motion smell -- or maybe just a wink Telecommunication is communication by electrical radio or optical . laser means. We introduce the basic capabilities and terminology of telecommunications and networking in this chapter. As hybrid words go telecommunications wins no prizes but it is all we have to work with. The greek tele prefix means distant and nothing else communication in the sense of information passed to and fro between human beings and animals is an activity that goes back beyond recorded times. With a broad view long distance communications brings to mind Armada beacons heliographs flashing between Frontier posts empires held together by relays of post-houses whales singing to one another in the deep and the family dog which conducts its social life by laying and following scent trails. For the narrower purposes of this book telecommunications is going to mean the transfer of information by electromagnetic means and with this will go a certain amount of accepted jargon . All systems have much in common whatever their age. In principle each requires a