2. What is a Telecommunications
System?
Communication of
information by
electronic means
• Digital Data Transmission
• Video/Audio
Transmission
Ø Transmit information
Ø Establish interface between
sender end receiver
Ø Route messages along most
efficient paths
Ø Perform processing of
information and data
Ø Convers message
speed/format
3. How is information transmitted?
Signals
Analog Signals Digital Signals
Ø Continuous waveform
Ø Passed by
communications
medium
Ø Used for video/audio &
voice communication
Ø Discrete waveform
Ø Transmits data coded into
two discrete states: 1-bits
& 0-bits
Ø Used for data
communication
Modem
converts signals
4. Communications Channels
Wired Transmission
Ø Twisted wire
Ø Coaxial Cable
Ø Fiber Optics and Optical
Networks
Wireless
Transmission
Ø e.g. satellites,
Ø cellphones,
Ø mobile data networks,
Ø microwaves
5. Communications Networks
Star Networks
Ø All computers and other
devices connected to a
central host CPU
Bus Networks
Ø Several computers
linked by one single
circuit
Ring Networks
Ø All computers linked by
a closed loop
6. Local Area Networks and Wide Area Networks
Local Area Network
Ø Require their own
dedicated channels
Ø Limited distance
Ø Require network gateway,
router & network operating
system
Wireless Local Area
Network
Ø Up to 11 Mbps
Ø low cost
Ø high speed
internet access
Wide Area Network
Ø Connect different networks
together
Ø For large geographical
distances
Ø Consist of a variety of
communication
technologies
7. Electronic Commerce and Business Technologies
Email
Groupware
Voice
Mail
Fax
Tele-
conferencing
Data-
conferencing
Video-
conferencing
E-Learning
Distance
conferencing
8. Electronic Commerce and Business Technologies
Electronic Data Interchange
Electronic Data Interchange is a direct computer-to-computer exchange
between two organizations or customers. For example, transactions
documents or money transfers can be exchanged via the internet.
