Telecommunications. Telecommunication is the transmission of signals over a distance for the purpose of communication. - презентация

1 Telecommunications

2 Telecommunication is the transmission of signals over a distance for the purpose of communication.

3 The basic elements of a telecommunication system 1) A transmitter that takes information and converts it to a signal or code for transmission. a.The transmission may be a broadcast transmission that is sent to multiple receivers or a point-to-point transmission to a single receiver. 2) A transmission medium over which the signal is transmitted. a.Common mediums are: free space, cable, and optical fiber. 3) A receiver that converts the signal back to useable information. a.Some systems use transceivers which serve as both transmitter and receiver (ex. Telephone).

4 Telecommunication Networks The elements of a system may be linked with other systems to form a network of systems that communicate with each other. Modern telecommunication systems use either an analogue or a digital signal. Varying the modulation creates analogue signals. Digital signals use a series of 1s and 0 s as a code.

5 Telecommunication Networks Private Networks: a group of two or more computer systems linked together which does not provide outside access. Computers deliver Digital Information, the concept of meaning, knowledge, instruction, communication, representation, and mental stimulus through the Internet and other electronic resources, using digital code.

6 Internet -The biggest computer network reaching millions of people on interconnected networks. The Internet began in 1940 when George Stibitz transmitted problems from Dartmouth College in New Hampshire over teletype to his Complex Number Calculator in New York. A four node network developed between UCLA, the Stanford Research Institute, the University of Utah and the University of California, Santa Barbara during the late 60s. This network known as ARPANET had grown to 213 nodes by the early 80s.

7 LANs, WANs, and the WWW Local area networks (LANs) begin to develop. Wide Area networks (WANs) consisting of two or more LANs connected by host computers formed covering wider geographical areas. These early networks formed the World Wide Web (WWW) eventually allowing users access to text, graphics, sound and video. There was no master plan or oversight, an Acceptable Use Policy (AUP) was developed by non-profit organizations as the WWW continued to grow.

8 Internet Service Providers (ISP). ISP companies (ex:AOL, Earthnet) offer connection to the Internet through servers and routers. Servers are powerful computers with large databases of internet addresses; routers are computers that direct the server to the quickest path to an internet site. To connect to the ISP companys server the user must have matching web browser software. The web browser gives the computer instructions about transforming data to protocol the server recognizes. The users computer connects through a modem that transfers the digital signal into a signal suitable for the transmission medium to the ISPs server.

9 Internet Protocol (IP): Internet servers use IP addresses to identify individual computers web locations. IP addresses are a series of numbers that are sequenced in a manner to identify locations by subdivisions, much as phone numbers and zip codes do.

10 Domain Name System The University of Wisconsin created the Domain Name System (DNS) in The system links text names to IP addresses automatically. Web addresses known as Uniform Resource Locators (URL) use specific text domain names that often give hints to the content of the site or address.

11 First Level Domain Addresses The.asp at the end of the URL is the school sites first level domain. First level domain addresses identify the type of site being located, they include:.asp - application software provider.com- commercial sites.org- organizations.net- networks.edu- education (primarily used by universities).gov- government

12 Web-sites Websites begin with a homepage, which not only introduces the site but also uses links to jump to other pages within the site when clicked. Hyperlinks and hypertext take the user to related information in other sites. The navigation of a site may use button bars or other graphics which are highlighted in a different color than the other text and graphic borders to help identify the link. A small hand appears on the screen when the pointer is over a link.

13 Types of Web-sites Blog, short for Web log, is a webpage that serves as a publicly accessible personal journal for an individual. Typically updated daily, they often reflect the personality of the author. Threaded Discussion is a set of related messages in an online group or . One of these includes the initial message and all replies to that message.

14 Internet/ Web-Site Features Computers may have filters using content control software to screen content from web-sites. Bookmarks/Favorites allows the computer to form a list of URL addresses for often used web sites. The sites may be opened with a click without typing in URL addresses File Transfer Protocol allows the exchange of files over the internet.

15 (electronic mail): Has become one of the most widely used types of communication. is used by individuals or companies to communicate written messages to other individuals or companies. Unsolicited or Spam is used in mass mailings to advertise products or causes. Often referred to as junk mail it can clog accounts.

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