Definition

  • A computer network is a number of computers linked together to enable them to share computing resources.
  • Networks can be permanent (via cables) or temporary (via modem)
  • The sharing of resources through a network can also be local or global
  • Networks allow different types of computers to communicate.

Benefits

  • Information can be accessed in remote areas that is part of the network
  • Information can be shared easily
  • Information generated by a single user can be shared world-wide instantaneously.
  • Networks can maintain a single file without copying entire file to computer.
  • Resources can be shared easily
  • One shared file rather than many separate files
  • Physical resources can also be shared (e.g. printer)
  • Transferring signals on a network
  • To transfer information on a network, we need to consider three areas.
    • Hardware needed to transmit information over the network
    • Most cost-effective method to transmit and receive the signals
    • An standard to code and decode signals (e.g. ASCII)

Analog Transmission

  • An analog signal is a continuous wave that reflects variation.
  • a telephone mainly uses analog signals for local distribution
  • Digital Transmission
  • A digital signal is in binary format (i.e. 1’s and 0’s)
  • Digital lines are faster and more accurate
  • Can handle text, graphics, voice, video at high speeds.
  • HIGH cost!
  • Modem (MOdulator/DEModulator)
  • Many computers are connected to the internet via a phone line. However:
  • Computers are digital
  • Phone lines are analog
  • Modems provide a link between digital computers and analog phone lines.
  • Modems convert:
  • digital signals to analog signals (modulation)
  • Analog signals to digital signals (demodulation)

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