Lesson 9 communication


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Communication for 3ESO students

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Lesson 9 communication

  1. 1. Communication technologies Technology 3 ESO
  2. 2. Index            What is communication? What are the main components of communication ? What kinds of communication technologies exist? Communication signals Guided communication Non guided communication: electromagnetic space Telephone: Conmutation and mobile phones Radio Television GPS Internet
  3. 3. What is communication?  Communication is a proccess in which two or more agents interchange information Index
  4. 4. Elements of Communnication  Emisor, who produces the message and sends it  Receiver: who receives the message (emisor and receiver often interchange roles during the communiaction proccess)    Message: information sent from one to another Channel: The form of interchanging information. i.e: radio, press, TV, telephony… Medium: the physical which information flows through. i.e: paper, space, wires… Index
  5. 5. Classification of communication Technologies    Communication technologies are often classiffy according to the medium in: Guided: They use a material medium such as electric wires, optical fiber Non guided: the information is carried in waves thoruogh the space Index
  6. 6. Communication signals Communication sisgnals can be:  Analogic: Which can have whatever value in a range  Digital: which are coded binary and can be proccessed by a computer. Index
  7. 7. Guided communication     In guided communication, information flows thorough material elements: electric wires, optical fibre Before being send, communication is transformed into electric or optic signals. Electric wires: Much cheaper but suffers from interference and atenuation (the signal weakens with distance). i.e: telephony, Optic fibre: much more expensive and delecated but doesn’t suffer from interferences or atenuation: ADSL, digital TV Index
  8. 8. Non guided communication    In non guided communication, communication flows through the space in the form of electromagnetic waves. Radioelectric space (spectrum) is the whole range of frequencies or wavelengths of electromagnetic waves: it is divided in different regions: gamma, X, ultarviolet, visible, infrared, microwave and Radiofrecuencies (RF): the most usual communications use from IR to RF Terrestrial anthens and satellites are used to send, repeat and receive information. Index
  9. 9. Telephony    Telephony consists of interchanging acustic signals beetween an emisor and a receptor who interchange their roles. There are two kinds of telephony : Conmuted grid: telephones terminals are connected to a guided grid. A node system provides a guided way to connect the two terminals in communication. Mobile phones are connected by satellites which receive their signals and sends them signals from other terminals. They can also connect to the conmuted grid through speciphic devices. Last generation mobiles have turned into small/powerful multifunction devices with a powerful microproccessor inside Index
  10. 10. Radio   In radio, sound signals flow in form of waves from an emisor to a receiver, both having anthens. Radio has only one direction, the emisor and the receiver do not interchange their roles Index
  11. 11. Television   In television, audio and images are sent from an emisor to a receiver in the form of waves (anthens) or by a wire (TDT). There are different technologies to produce Index images in an screen_(plasma, RCV, LCD)
  12. 12. GPS (Global positioning system)    GPS was invented by the USA’s army A GPS uses a system of 8 or more satellites and a terrestrial receiver. The receiver and at least three satellites interchange signals. The time it takes to the signal to trip between them gives the receiver know the distance. Taking three signals of distance at the same time, the receiver works out its position in the earth’s surface. Index
  13. 13. Internet       Internet is a worldwide system of interconected computers which interchange information. There are different ways of connecting to the internet (transmmision protocols) TCP-IP: Where information is divided into small packages (TCP) and sent from a server (computer) to a client computer. P2P (peer to peer), where it doesn’t exist a client-server jerarchy. Computers share their hardware resources acting as servers or clients at the same time. Several devices are used to connect to the internet: modems, routers. Todays computers, PDA’s provide their on anthen to connect via wi-fi A specific software (explorers) are used to interchange information. Internet provides many different utilitis such as e-mail, information (web pages), news, telephony, videoconferences, virtual market, etc Index