Computer Concepts in Action ©2009

Unit 3: Using the Internet

The Internet and the Phone Network

Introduction:
Learn more about how data travels across the phone network and the Internet.

Directions:
Read the information below and apply what you learn to answer the questions.
Check your work carefully, and click Submit.

Partners in Communication
The worldwide telephone system is used to transmit information via a network, or collection of smaller networks, in order to allow any telephone user to reach another. This is made possible by telephone standards, guidelines, and procedures which are practiced worldwide.

There are two types of telephone networks:

  • Standard uses physical connections (wires, cables or fiber optics).
  • Cellular uses air waves (analog or digital).

The telephone network is used to send and receive different information types:

  • Sound (voice)
  • Images (fax documents)
  • Data (modem)

Computers transmit information over the telephone system by using a modem to convert data from digital format (binary 1s and 0s) to analog format (waveform). Once the data is in analog format, it is sent over phone lines until it reaches another computer and is converted back into digital format.

The Internet, like the telephone network, is actually a collection of smaller networks that can communicate because of universal standards, guidelines, and procedures. A computer accesses the Internet via an "onramp" of a smaller network, such as a LAN (local area network) or a home user's ISP (Internet service provider). The information then travels over an Internet backbone until it reaches the desired destination. Internet backbones are made of fiber optic lines which provide very fast transmission of data.

Different types of Internet connections include:

  Type of
  Internet   Connection

  Description

  Speed

  Dial-up modem

  • Uses regular phone lines
  • The modem converts from digital to analog for outgoing data and analog to digital for incoming data
  • Available almost everywhere
  • The slowest option

56 Kbps
(Kilobytes per second)

  Cable modem

  • Uses cable television lines to transmit digital data
  • The connection is always on, which can lead to security problems
  • Generally very reliable

Up to 5 Mbps (megabytes per second)

  DSL
  (Digital Subscriber   Line)

  • Uses copper phone wires to transmit digital data
  • Like a cable modem, the connection is always on
  • Generally very reliable

Up to 10 Mbps

  ISDN

  • Uses dedicated copper phone lines to transmit digital data
  • Slower than cable or DSL (and about the same price), but faster than dial-up

128 Kbps

  T1

  • Popular option for businesses
  • Usually carries data over fiber optic lines
  • Very reliable and fast but expensive

Up to 1.5 Mbps

  Satellite

  • Relays signals from antennas to satellites
  • The antenna must have a clear view of the southern sky
  • More expensive than cable or DSL

Up to 1 Mbps

  Wireless

  • Available at "hot spots" like cafes, airports, and hotels as well as homes and businesses
  • Requires a wireless Internet access account and a laptop with a Wi-Fi card

Up to 2 Mbps

Assessment Questions

1
Name two types of telephone networks.
2
Why are telephone and Internet networks able to function across countries?
3
Name four different types of Internet connections.
4
What are the three types of information transmitted on the telephone network?
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