Communication Systems




MAS - 12 IPT                           1
Introduction
      Communication    is the transfer of data from
       one location to another
      Examples include:
...
Requirements of a
               Good Comms System
      message  must arrive accurately
      message arrives as quickl...
Elements of a Comms System
      Every    comms system has these common
          elements:
               –   sender
   ...
Medium - Links
      A link is a connection between computer
       devices. In the past, data communication
       used ...
Twisted Pair
      Communications        cable
          consisting of pairs of plastic-
          coated copper wires th...
Coaxial Cable
      Coaxial  cable is a combination of two or
       more insulated wires that run inside one
       anot...
Fibre Optics
      Fibre optics is a technology in which signals
       are converted from electrical into optical
      ...
Comparison of Cable Links
      TYPE OF CABLE            ADVANTAGES                 DISADVANTAGES
     Twisted Pair       ...
Microwave Links
      Microwave    links are non-cable links often
       used for longer distances.
      They transmit...
Microwave Research Activity
      Try    to find answers to the following
          questions:
               – what is th...
Because      the microwave beam travels in a
          straight line, hardware elements must negate
          the earths’...
Infrared Links
       Infrared  light beams are used to transmit data
          between devices that are in the same gene...
Input/Output Devices
      In    order to transmit data many different
          input/output devices are used, including...
Modems
      Modem    is short for modulator-
       demodulator.
      Modems can be fitted internally to an
       expa...
Modem Communication Process
                                                           Picture of a typical looking
      ...
Acoustic Couplers
      An acoustic coupler is a cheaper type of
       modem that has a cradle for a telephone
       ha...
Facsimiles
       Facsimile, or fax, equipment is used to
        transmit an image of a document over the
        teleph...
Many     PCs use fax equipment and a modem
          to send documents over telephone lines.
          This can be sent t...
POST
      Stands for Point Of Sale Terminal
      Most shops have the facilities to do
       EFTPOS, which uses card s...
Internet Activity
      Research  one of the following on the
       internet and answer the questions below:
      Real...
Networks
       A network   is a system in which computers
        are joined to each other in order to exchange
        ...
Research Activity
      Use    reference books and/or the internet to
          answer one of the following questions:
  ...
Servers
      A server is a computer that shares it’s
       resources across a network.
      There are four types of s...
Direct Communication
      When      computers are connected directly, the
          transfer of data is very fast.




M...
Indirect Communication
      Other    hardware is required where
          computers aren’t directly connected. Most
    ...
Hubs
      A central    connecting point for devices such
          as computers, printers, and storage devices
         ...
Routers
      An     intelligent network connecting device
          that sends (routes) communications traffic
          ...
Communication Software
      Programs       that perform data
          communications tasks such as dialing, file
       ...
Ethernet
      The    most widely used network protocol for
          LAN networks; can transmit data at 10 or
          ...
Upcoming SlideShare
Loading in …5
×

Communications Systems

1,496 views

Published on

Communications systems was a topic I taught in senior high school and this presentation collected several definitions and examples of networking concepts.

Published in: Education
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
1,496
On SlideShare
0
From Embeds
0
Number of Embeds
8
Actions
Shares
0
Downloads
80
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide






























  • Communications Systems

    1. 1. Communication Systems MAS - 12 IPT 1
    2. 2. Introduction Communication is the transfer of data from one location to another Examples include: – computer to printer – computer to comp. on a network – terminals to M’frame comp. – comp. to server – comp. to dish to satellite to dish to comp. MAS - 12 IPT 2
    3. 3. Requirements of a Good Comms System message must arrive accurately message arrives as quickly as possible cost should be less (in time, money and quality(more)) than other methods of communicating data. equipment should be reliable data should be secure, available only to authorised people MAS - 12 IPT 3
    4. 4. Elements of a Comms System Every comms system has these common elements: – sender – receiver – message – medium Activity: Write a definition for each element, including an example. MAS - 12 IPT 4
    5. 5. Medium - Links A link is a connection between computer devices. In the past, data communication used cables only. New technology has meant that non-cable links are commonly used today. Cable links include twisted pair, coaxial and fibre optics. Non-cable links include satellites, satellite dishes, ground stations and infrared. MAS - 12 IPT 5
    6. 6. Twisted Pair Communications cable consisting of pairs of plastic- coated copper wires that are twisted together. A thin layer of coloured plastic insulates and identifies each wire; the wires are then twisted to reduce electrical interference. Most commonly used in telephone cables. Susceptible to interference. MAS - 12 IPT 6
    7. 7. Coaxial Cable Coaxial cable is a combination of two or more insulated wires that run inside one another. It is protected well from interference and is faster than twisted pair. However, it is a heavier cable than twisted pair and more expensive to install. Shield Conductor Insulation MAS - 12 IPT 7
    8. 8. Fibre Optics Fibre optics is a technology in which signals are converted from electrical into optical signals, transmitted through a thin glass fibre, and re-converted into electrical signals. The concentric layers of an optical fibre include the light-carrying core, the cladding and the protective buffer. Buffer Cladding Core MAS - 12 IPT 8
    9. 9. Comparison of Cable Links TYPE OF CABLE ADVANTAGES DISADVANTAGES Twisted Pair 1. Inexpensive 1. Susceptible to RFI Cable 2. Often available in and EMI existing phone system 2. Not as durable as 3. Well tested and easy coax to get 3. Doesn't support as high a speed as other media Coaxial Cable 1. Fairly resistant to RFI 1. Can be effected by and EMI strong interference 2. Supports faster data 2. More costly than TP rates than twisted pair 3. Bulkier and more rigid 3. More durable than TP than TP Fiber Optic Cable 1. Highly secure 1. Extremely costly in 2. Not affected by RFI product and service and EMI 2. Sophisticated tools 3. Highest bandwidth and methods for available installation 4. Very durable 3. Complex to layout and design NOTE: Radio Frequency Interference (RFI) and Electromagnetic Interference (EMI) MAS - 12 IPT 9
    10. 10. Microwave Links Microwave links are non-cable links often used for longer distances. They transmit data using radio waves at a very fast rate. Both voice communications and digital signals can be transmitted. MAS - 12 IPT 10
    11. 11. Microwave Research Activity Try to find answers to the following questions: – what is the difference between microwaves and radio waves? – what materials can microwaves bounce off? – what materials are satellite/microwave dishes made from? – try: www.howstuffworks.com MAS - 12 IPT 11
    12. 12. Because the microwave beam travels in a straight line, hardware elements must negate the earths’ curves and provide line-of-sight between sender and receiver. MAS - 12 IPT 12
    13. 13. Infrared Links  Infrared light beams are used to transmit data between devices that are in the same general area. An example is between computer devices. This method is good because it doesn’t require cables, however, it is slower and more susceptible to interference. MAS - 12 IPT 13
    14. 14. Input/Output Devices In order to transmit data many different input/output devices are used, including: – modems – acoustic couplers – facsimile transceiver – point of sale terminal (POST) – automatic teller machine – teletext keypad MAS - 12 IPT 14
    15. 15. Modems Modem is short for modulator- demodulator. Modems can be fitted internally to an expansion slot or externlly via a port. Modems convert the computer’s digital signal into an analog signal (called ‘modulation’) required by the telephone lines and vice versa (called ‘demodulation’). Both sending and receiving computers require modems. MAS - 12 IPT 15
    16. 16. Modem Communication Process Picture of a typical looking external modem Modems Telephone Line 1 1 1 1 1 1 1 1 0 0 00 0 0 00 Digital data Analog data Digital data Modulation Demodulation MAS - 12 IPT 16
    17. 17. Acoustic Couplers An acoustic coupler is a cheaper type of modem that has a cradle for a telephone handset. They are not as good at coding and decoding signals, and the rate of transfer is very slow. The advantage is the ability to use any phone handset around the world. MAS - 12 IPT 17
    18. 18. Facsimiles Facsimile, or fax, equipment is used to transmit an image of a document over the telephone lines. The document can contain text (hand-written or typed), graphics or even photographs. A fax machine scans the document and converts the image into digitised data, which is transmitted over a telephone line. The receiving fax converts it back into its original image. MAS - 12 IPT 18
    19. 19. Many PCs use fax equipment and a modem to send documents over telephone lines. This can be sent to a fax machine or another PC. The person who receives the fax on a PC can print the document to receive a hard copy. MAS - 12 IPT 19
    20. 20. POST Stands for Point Of Sale Terminal Most shops have the facilities to do EFTPOS, which uses card scanning devices to communicate with banks. Once the card is scanned the user is asked for account and PIN details. Confirmation is sought over dedicated lines between the shop and the bank. Occasionally lines are down and MAS - 12 IPT 20
    21. 21. Internet Activity Research one of the following on the internet and answer the questions below: Real-time auctions (start with www.internet auctionlist.com/New.asp) Global Positioning Systems Groupware MAS - 12 IPT 21
    22. 22. Networks A network is a system in which computers are joined to each other in order to exchange data or share hardware A network may comprise some or all of the following: – servers – terminals – hubs – routers – communication software – ethernet MAS - 12 IPT 22
    23. 23. Research Activity Use reference books and/or the internet to answer one of the following questions: – In what ways has the progress of communication technology reduced the world to a global village? – OR – Has the use of computer communication systems enhanced human communication? Be sure to include adequate detail. WP your answer. MAS - 12 IPT 23
    24. 24. Servers A server is a computer that shares it’s resources across a network. There are four types of servers: » file servers, used to share files » print servers, used to share printers » application servers, used to share application programs » communications servers, used share communications devices MAS - 12 IPT 24
    25. 25. Direct Communication When computers are connected directly, the transfer of data is very fast. MAS - 12 IPT 25
    26. 26. Indirect Communication Other hardware is required where computers aren’t directly connected. Most common transmission media is telephone line. Medium of Transmission 1 1 1 1 1 1 1 1 0 0 00 0 0 00 Digital data Digital data MoDem MoDem MAS - 12 IPT 26
    27. 27. Hubs A central connecting point for devices such as computers, printers, and storage devices that are connected to the server; also called concentrator, or multistation access unit. MAS - 12 IPT 27
    28. 28. Routers An intelligent network connecting device that sends (routes) communications traffic directly to the appropriate network; used when several networks are connected together. MAS - 12 IPT 28
    29. 29. Communication Software Programs that perform data communications tasks such as dialing, file transfer, terminal emulation, and Internet access, allowing data to be transmitted from one computer to another. MAS - 12 IPT 29
    30. 30. Ethernet The most widely used network protocol for LAN networks; can transmit data at 10 or 100 Mbps. MAS - 12 IPT 30

    ×