Transcript here

Telecommunications and
Networks
Chapter 8
Types of Signals
Analog – a continuous waveform
that passes through a
communications medium
 Digital signal is a discrete waveform.
It transmits data coded into two
discrete states: 1-bits and 0-bits.

Modem

Translate a computer’s digital signals
into analog form for transmission
over ordinary telephone lines, or it
translate analog signals back into
digital form for reception by a
computer
Transmission media
Twisted wire
 Coaxial cable
 Fiber optics
 Terrestrial microwave
 Satellite
 Wireless transmission

Transmission speed
Bit per seconds – total amount of
information that can be transmitted
through any telecommunications
channel
 56 Kilo bit per second for current
modem

Bandwidth
The difference between the highest
and lowest frequencies that can be
accommodated on a single channel
 The greater the range of
frequencies, the greater the
bandwidth and the greater the
channel’s transmission capacity

LAN
Local Area Network
 Encompasses a limited distance,
usually one building or several
buildings in close proximity
 Used to connect PCs in an office to
shared printers and other resources

Servers
May be powerful PCs with large
hard-disk capacity, workstations,
midrange computer, or mainframe
 Some specialized computers are
used for network connections

Gateway
Generally a communication
processor that can connect
dissimilar networks by translating
from one set of protocols to another.
 The network gateway connects the
LAN to public networks, such as the
internet

Router

Is used to route packets of data
through several connected LANs or a
wide area network
WAN
Wide area network
 Span broad geographical distances,
ranging from several miles to entire
continents

DSL
Digital Subscriber line
 Operate over existing copper
telephone lines to carry voice, data,
and video, but they have higher
transmission capacities

Cable modems
Modems designed to operate over
cable TV lines
 Provide high speed access to the
Web or corporate intranets of up to
4 megabits per second

T1 line
A dedicated telephone connection
comprising 24 channels that can
support a data transmission rate of
1.544 megabit per second
 Are used for high-capacity internet
connections

TCP/IP
Transmission Control Protocol /
Internet Protocol
 Developed by US department of
Defense in 1972
 Become Internet standard
 OSI (Open Systems Interconnect) is
another transmission model

Management Issues
New Way of life
 Managing the changes
 Planning for connectivity, bandwidth,
and reliability
 Security and privacy
