课题： Telecommunication Step I what is telecommunication The word telecommunication derives from the Greek word tele, meaning over a distance, plus the word communication. Thus, putting the two parts together, you get telecommunication- communication that spans a distance. An ancient example of telecommunication is the use of fire signals on hilltops those miles apart. These days, modern telecommunications is a vast field that encompasses everything from broadcasting to telephone technology to computer networks. TelecommunicationVoice Video DataWireline wireless wireline wireless wireline wireless Local+long cellular telephony video broadcast TV computers RF networksDistance conferencingTelephony digital cable radio broadcasting desktop video over networks satellite feeds LANs paging Intercom wireless local+long distance telephony cable TV WANs point-to-point services closed circuit TV The internet Figure 1. Telecommunication services Three categories of telecommunication are: voice, video and data. Voice telecommunication refers to any means of using electrical signals to transmit human voice across a distance, such as telephone and audio broadcasts. Video telecommunication refers to the electrically-based transmission of moving pictures and sound across a distance , such as TV broadcasting or distributing live feeds of an event to the screen of networked computers. Data telecommunication refers to use of electrical signals to exchange encoded information between computerized devices across a distance. Sending an e-mail to a colleague, retrieving a spread-sheet from your computer’s hard disk, and sending a message to your spouse’s pager are all examples of data telecommunications. Voice, video and data telecommunications all...
