Chapter 6 Basic Communication

1
Chapter 6 - Basic Communication

• Introduction
• Communication Using Electricity
• Signals On Wires
• Information Coding
• MODEM A Modulator and a Demodulator - A modem
  is a device needed for communication across a
  dial-up telephone connection or for long distance
  communication across a wire. A modem supports
  two-way communication because it contains a
  modulator for the signal being sent and a
  demodulator for the signal being received.

2
Chapter 6 - Basic Communication

• Modems Allow Two-Way Traffic
• A Character Code For Digital Information - ASCII,
  EBCDIC, UNICODE
• Detecting Errors
• When using electrical signals to communicate
  digital information, electrical or magnetic
  interference can cause the value of one or more
  bits to be changed
• Adding a parity bit to each character code before
  transmission can help the hardware detect errors
  that occur when transmitting the character across
  a network. However, parity alone is not
  sufficient to detect all possible errors more
  powerful techniques are neededcheck sums,
  Hamming codes