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Syllabus 

The concept of transmission rates               11 ATAR, 12 GEN


Background

  • For a network to work correctly it needs to have connectivity.
  • But. How fast is this connectivity?
  • That depends on the type of connectors and transmission medium.
  • Transmission of data is the speed of the data moving from one place to another.

How is it measured?

  • it is measured by how many units pass through the network in a given time
  • commonly this is bits per second or bps
  • some people call it upload or download speed, or bandwidth
  • you may have heard it called megabits per second

Transmission unit

  • bits per second = bps
  • kilobits per second  = kbps = 1000 bits per second or 1024 bits per second
  • megabits per second = mbps = 1000 kb per second or 1024 kb per second

Transmission rate influencing factors

  • wireless - range; if close, it will transmit faster, concrete walls, metal plates or chicken wire in walls; goes very slow or stops, interference from microwave ovens, other electrical devices
  • old copper phone lines - straight wires in plastic sheath, interference from other wires
  • twisted pair - twisted wires in plastic sheath, less interference from other wires because of the many twists
  • optic fibre - light transmitting pulses; not influenced by interference
  • other clients online cable speed greatly reduced by more clients online, wireless speed greatly reduced by more clients online

Transmission rates

  • dial up = 56 Kbps
  • ADSL = 512 Kbps- 2Mbps
  • cable = 512 Kbps- 2Mbps
  • Satellite = 512 Kbps
  • Optic Fiber = 100 Mbps (but only with no copper wires in the system anywhere)

Tools to measure transmission speed

  • the download rate and time are visible at the bottom of the screen  when downloading off the internet
  • many web services can measure your upload and download speed eg whatismyip    speedtest.net 

 For You To Do

  1. Choose one of the topics from above.
  2. Explain it to a friend in the class. The friend and you discuss it further.
  3. As a pair, you tell the class.
 Learn more from bit rate at wikipedia, by device medium at wikipedia
 
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