Telecommunications

and Networks

Rev 7/20/07 rdm

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Objectives

Understand the fundamentals of data communications and the criteria for choosing a communications medium

Explain how networking media, devices, and software work together to provide data networking services

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Fundamentals of Telecommunications Communications

Transmission of a signal by way of a medium

Signal

Contains message comprised of data and information

Communication medium

Anything that carries a signal between a sender and a receiver

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Telecommunications and Data Communications Telecommunications

Electronic transmission of signals for communications

Data communications Electronic collection, processing, and distribution of

data Telecommunications network

Connects communications and computing devices Networking media

Anything that carries an electronic signal

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Characteristics of Telecommunications Analog signal

Continuously changes over time

Digital signal

At any given time is either high or low

Signal frequency

Speed at which signal can change from high to low

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Transmission Capacities

Bandwidth Range of signal frequencies that can be sent over a

given medium at the same time Broadband media

Significantly faster than narrowband Any media faster than 200 Kbps (kilobits per

second) or 2 Mbps (megabits per second) Narrowband

Anything below 200 Kbs

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Networking Media Twisted-pair cable

Cable consisting of pairs of twisted wires Repeaters

Used to boost signal so that it can travel longer distances

Coaxial cable Inner conductor wire surrounded by insulation, a

conductive shield, and a cover Fiber-optic cable

Thousands of thin strands of glass or plastic bound together in a sheathing

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Networking Media (Continued) Microwave transmission

High-frequency radio signal that is sent through the air

Communications satellite

A microwave station placed in outer space

Global positioning system (GPS)

Uses satellites to pinpoint the location of objects on earth

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Networking Media (Continued) Wireless fidelity (Wi-Fi)

Wireless networking devices that use the 802.11 protocol

Uses wireless access points Bluetooth

Enables digital devices to communicate wirelessly over short distances

Communicates at speeds of up to 1 Mbps within a range of up to 33 ft

Infrared transmission Sending signals through the air via light wave

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Networking Devices

Modems Modulates and demodulates signals Cable modem

Provides Internet access over a cable television network

DSL modem Connects digital devices using a digital signal over

telephone service (POTS) lines Network adapter

Computer circuit board, PC Card, or USB device

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Network Control Devices

Hubs Used as a central point for connecting a series of

computers Switches

Fundamental part of most networks Repeaters

Connect multiple network segments Bridges

Connect two or more network segments

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Network Control Devices (Continued) Gateway

A network point that acts as an entrance to another network

Routers Can divide a single network into two logically

separate networks Wireless access point

Receives and transmits data to wireless adapters Firewall

Device or software that filters the information coming onto a network

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Radio Frequency Identification (RFID) Devices

Tiny microprocessor combined with an antenna

Tracks merchandise from supplier to retailer to customer

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Summary

Telecommunications Electronic transmission of signals for communication

Computer network Connects computers for data communications

Network media Cables and wireless signals

Networking devices Modems, network adapters, network control

devices, RFID devices, and pagers