1. The Internet and the World Wide Web
CHAPTER 3
The Internet and the World Wide Web

2. LEARNING OUTCOMES
At the end of this class, students should be able to:
Describe the telecommunication system
Explain and differentiate the types of computer networks

3. CHAPTER REVIEW Basic Elements in Telecommunications System
Sending and receiving devices
Communication channels
Connection devices
Data transmission specifications
Types of Networks
LAN
MAN
WAN

4. Communications Today
Numerous applications depend on communication systems— , Instant messaging (IM) and Social Networking.
Connectivity uses computer networks to link people and resources.
Wireless revolution
Use of mobile or wireless devices
Many devices can and will connect to one another without any physical connection
Picture source:
Connectivity is a concept related to using computer networks to link people and resources
Microcomputers. minicomputers, and mainframes can all be connected
Wireless revolution
Use of mobile or wireless devices
The revolution is the support of more than just the wireless telephone
Many devices can and will connect to one another without any physical connection

5. THE TELECOMMUNICATION SYSTEM
Electronic systems that transmit data from one location to another
Communication systems can be wired or wireless
Four basic elements:
Sending and receiving devices
Communication channel
Connection devices
Data transmission specifications
Electronic systems that transmit data from one location to another
Communication systems can be wired or wireless
Basic elements
Sending and receiving devices – computer or a specialized communication device
Communication channel – carries the message
Connection devices – act as an interface between sending and receiving devices
Data transmission specifications – rules and procedures that coordinate the sending and receiving devices

6. Sending and Receiving Devices
These are often a computer or specialized communication device.
They send as well as receive messages in the form of data, information and/or instructions.

7. Communication Channels
Channels carry data from one computer to another
Two categories of communication channels
Physical connection
Wireless connection
Channels are essential to a communication system
They carry data
Types of channels
Telephone lines (key term)
Coaxial cables
Fiber-optic cable (key term)
Infrared (key term)
Broadcast radio (key term)
Microwave (key term)
Satellite

8. Physical Connections
Twisted-pair cable (Telephone lines) consists of twisted pair cable; slowest; being phased out by more advanced and reliable media
Coaxial cable single solid copper core; 80 times transmission of twisted pair; television and computer networks
Fiber-optic cable
26,000 times capacity of twisted pair cable; more secure and reliable; best over limited distances; lighter, more reliable, and less expensive than coaxial cable
Telephone lines – consists of twisted pair cable; slowest; being phased out by more advanced and reliable media
Coaxial cable – single solid copper core; 80 times transmission of twisted pair; television and computer networks
Fiber optic – 26,000 times capacity of twisted pair cable; more secure and reliable; best over limited distances; lighter, more reliable, and less expensive than coaxial cable

9. Wireless Connections
Wireless connections do not use a solid substance to connect; uses the air itself
Types of wireless connections are:
Infrared
Light waves used over short distances
Sometimes called line of sight communications
Sending and receiving devices must be in clear view of one another
Examples: mouse, wireless keyboard, printer
Broadcast radio
Uses towers called transceivers
Web-enabled devices follow a standard known as Wi-Fi (wireless fidelity)
Wireless connections do not use a solid substance to connect; uses the air itself
Types of wireless connections are:
Infrared
Light waves used over short distances
Sometimes called line of sight communications
Sending and receiving devices must be in clear view of one another
Broadcast radio
Uses towers called transceivers (key term)
Web-enabled devices follow a standard known as Wi-FI (wireless fidelity)
Microwave
Uses high-frequency radio waves
Also line of sight
Used for short distances
Bluetooth used for distances up to 33 feet (not line of sight)
Satellite uses satellites orbiting about 22,000 miles above the earth as microwave relay stations; many of these offered by Intelsat, the International Telecommunications Satellite Consortium which is owned by 114 governments and forms a worldwide communications system
Satellites can be used to send and receive data; Uplink (key term)
is sending data to satellite and Downlink (key term) refers to receiving data from a Satellite
GPS (Global Positioning system) (key term) use a network of 24 satellites owned and managed by the Defense Department which continuously sends location information to earth

10. Wireless Connections Types of wireless connections are: Satellite
Microwave
Uses high-frequency radio waves
Also line of sight
Used for short distances
Bluetooth used for distances up to 33 feet (not line of sight).
Satellite
Satellite uses satellites orbiting about 22,000 miles above the earth as microwave relay stations
Satellites can be used to send and receive data;
Uplink is sending data to satellite and
Downlink refers to receiving data from a Satellite
GPS (Global Positioning system) use a network of 24 satellites owned and managed by the Defense Department which continuously sends location information to earth.
Wireless connections do not use a solid substance to connect; uses the air itself
Types of wireless connections are:
Infrared
Light waves used over short distances
Sometimes called line of sight communications
Sending and receiving devices must be in clear view of one another
Broadcast radio
Uses towers called transceivers (key term)
Web-enabled devices follow a standard known as Wi-FI (wireless fidelity)
Microwave
Uses high-frequency radio waves
Also line of sight
Used for short distances
Bluetooth used for distances up to 33 feet (not line of sight)
Satellite uses satellites orbiting about 22,000 miles above the earth as microwave relay stations; many of these offered by Intelsat, the International Telecommunications Satellite Consortium which is owned by 114 governments and forms a worldwide communications system
Satellites can be used to send and receive data; Uplink (key term)
is sending data to satellite and Downlink (key term) refers to receiving data from a Satellite
GPS (Global Positioning system) (key term) use a network of 24 satellites owned and managed by the Defense Department which continuously sends location information to earth

11. Communication Channels Summary

12. Connection Devices
These devices act as an interface between the sending and receiving devices and the communication channel.

13. Connection Device Signals
Types of modem signals
Analog
telephone signals; continuous electronic wave
Digital
computer signals; presence or absence of an electronic pulse; on/off
Signals
Sent analog – telephone signals; continuous electronic wave
Sent digital – computer signals; presence or absence of an electronic pulse; on/off

14. Connection Device - Modem
Modem is short for modulator-demodulator.
Modulation is the process of converting from digital to analog.
Demodulation is the process of converting from analog to digital.
The modem enables digital microcomputers to communicate across analog telephone line.

15. Connection Device Types and Transfer Speeds
Types of modems
External
stands apart from the computer is typically connected with a cable
Internal
built into the computer system unit already
PC Card
credit card-size expansion board that is inserted into portable computers; telephone cable connects the modem to the telephone wall jack
Wireless
may be external, internal, or a PC card
Does not use cables
Signals are sent through the air
Transfer Speed or transfer rate is measured in bits per second; the higher the speed the faster the transfer rate
Modem – modulator-demodulator
External – stands apart from the computer is typically connected with a cable
Internal – built into the computer system unit already
PC card – credit card-size expansion board that is inserted into portable computers; telephone cable connects the modem to the telephone wall jack
Wireless modem (key term) may be external, internal, or a PC card
Does not use cables
Signals are sent through the air
Transfer Speed (key term) or transfer rate (key term)-measured in bits per second; the higher the speed the faster the transfer rate
Transfer Speeds

16. Data Transmission Specifications
It is the rules and procedures that coordinate the sending and receiving devices.

17. Networks
A computer network is a communication system that connects two or more computers.
The benefit of network is:
It allows information exchange and share resources
A computer network is a communication system that connects two or more computers so that they can exchange information and share resources

18. TYPES OF NETWORK Local Area Network (LAN)
Metropolitan Area Network (MAN)
Wide Area Network (WAN)
Communications networks differ in geographical size. Three important types are:
1)LANs
Computers and devices linked in close proximity to each other
Linked by cable
Typically use a bus (key term) form of organization
With gateways, LANs can be connected to other LANs or any other type of network
Home Networks – LANs are now being commonly used by individuals in home/apartments; allow different computers to share resources including a common Internet connection; can be connected by various means including a wireless LAN (key term) (WLAN) that uses radio frequencies to connect computers
Home networking includes the following:
Radio frequency, telephone lines, electric wiring, cables, NIC/adapter cards
2)MANs (metropolitan area network)– also known as a regional network; (key term) span distances up to 100 miles
Network linking nodes and resources within the geographical bounds of a city
Cellular phones can extend the reach of a MAN
3)WANs (wide area networks)
Countrywide and worldwide networks
Use microwave relays and satellites to reach users
Internet is the widest WAN

19. Local Area Network (LAN)
Networks with nodes that are in close physical proximity, within the same building for example, are called local area network.
Typically, LANs span distances less than a mile and are owned and operated by individual organizations.
LANs are widely used by colleges, universities and other types of organizations to link microcomputers and to share printers and other resources.
LAN

20. Metropolitan Area Network (MAN)
MANs span distances up to 100 miles.
It is frequently used as links between office buildings that are located throughout a city.
Unlike a LAN, a MAN is typically not owned by a single organization. Rather, it is either owned by a group of organization who jointly own and operate the network or by a single network service provider who provides network services for a fee.

21. Wide Area Network (WAN)
Wide area network are countrywide and worldwide networks.
Typically, WANs span distances greater than 100 miles.
WANs use microwave relays and satellite to reach users over long distances, for example, from Malaysia to Japan.
The widest of all WANs is the Internet, which spans the entire globe.