WHAT IS DATA COMMUNICATIONS

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WHAT IS DATA COMMUNICATIONS ?
Transmission of data and information between two
or more computers
Examples of how communications is used 1.
Livestock Marketing
Farmers Paddock
Buyers Location
Farmers Paddock
Buyers
Local Sale yards
CALM - Computer-Aided Livestock
Marketing. ASSESSOR PORTABLE MAINFRAME
COMPUTER (SYDNEY)
Potential buyers access Mainframe for stock
details.
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EXAMPLES OF HOW COMMUNICATIONS IS USED

• Electronic data interchange (EDI)
• Reduced paper flow
• Lower transaction costs
• Faster transmission of documents
• Reduced data entry errors

• Global positioning systems (GPSs)
• Determine geographic location
• Tracking and navigation
• Measuring distances

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EXAMPLES OF HOW COMMUNICATIONS IS USED

• Online services
• Subscription basis
• Services
• Electronic banking
• Shopping
• News
• Weather
• Hotel and airline information
• Investment information

The Internet
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DATA COMMUNICATION COMPONENTS
Computer Telephone Line
Computer Terminal Radio Waves
Terminal Microwaves
software Twisted
Pair software Co-axial Cable
Fibre-optic Cable Satellite
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TRANSMISSION MEDIA

• To be sent from one location to another, a signal
  must travel along a physical path
• The physical path that is used to carry a signal
  between a signal transmitter and a signal
  receiver is called the transmission medium
• Network transmission media - the various types of
  media used to carry the signal between computers
• There are two types of transmission media

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TRANSMISSION MEDIA
Guided media
The three most common types of guided media
include twisted-pair wiring, coaxial cable, and
fiber optic cable
Twisted-pair wiring The wires are twisted to
reduce outside electrical interference The
RJ-45 connectors on twisted-pair cables resemble
large telephone jacks
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TRANSMISSION MEDIA
Coaxial cable Consists of a metallic shield
with a single wire placed along the center of a
shield and isolated from the shield by an
insulator
Fiber optic (or "optical fiber") the technology
associated with the transmission of information
as light impulses along a glass or plastic wire
or fiber Optical fiber is not subject to
interference
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TRANSMISSION MEDIA
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TRANSMISSION MEDIA
Unguided media Natural parts of the Earths
environment that can be used as physical paths to
carry electrical signals
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Modem

• MODEM
• Most communications media are not digital but
  ANALOG.
• A modem is a device that converts a digital
  signal to an analog signal and vice versa

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DIRECTION OF DATA COMMUNICATIONS
Data transmission can be described by the
direction the data is flowing. They are
SIMPLEX
HALF-DUPLEX
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DIRECTION OF DATA COMMUNICATIONS
FULL DUPLEX
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OTHER ISSUES

• Employment
• The explosion in computer usage has produced
  employment opportunities in
• the Computer Industry maintenance, sales,
  manufacture etc.
• General job shift
• less low skill jobs, (which are often even less
  skilled, eg. check-out)
• new jobs created are high skill

• 2. Crime
• The computer has made the committing of crimes
  more efficient.
• Computer Security Risks include
• System Failure
• Information Theft
• Software Theft
• Hardware Theft
• Computer Viruses, worms trojan horses
• Unauthorised access and use

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OTHER ISSUES (CONTD)
Virus potentially damaging computer program
that infects a computer and may damage files and
system software.
Worm copies itself repeatedly using up
resources and possibly shutting down the computer
or network
Trojan Horse
How a Virus can spread through an e-mail message
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OTHER ISSUES (CONTD)

• 3. Security
• A computer system owner may choose to build a
  number of controls and safeguards into their
  system to protect the system and its data against
  accidental or deliberate damage.
• Access requirements
• physical - ID card
• software - password
• voice recognition
• finger print reader
• laser eye scan
• Cryptographing of communicated data (encryption)
• Development of a disaster recovery plan.

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OTHER ISSUES (CONTD)
4. Privacy In our modern society, vast amounts of
data is required about individuals to manage the
community at a broad level. Eg. Collection of
taxes. Computers provide a way in which large
amounts of data can be stored cheaply but the
security of such data is not ensured. Issues Pa
perwork for loans, bank accounts, magazine
subscriptions, insurance claims, Medicare,ATO,
Centrelink.