1. Communications

2. Networks
A network is a collection of computers, display terminals, printers and other devices linked either by physical or wireless means

3. Communication Basics of Networks
Types of connections of computers into networks: Physical versus Wireless connections
Physical: computers are physically connected with twisted pair, coaxial cable or fiber-optic cable

4. Communication Basics of Networks
Twisted pair : two wires twisted together makes them less susceptible to acting like an antenna and picking up radio frequency or noise.
Telephone companies still use twisted pair copper wires

5. Communication Basics of Networks
Coaxial cable: also two wires however one of the wires is woven of fine strands of copper forming a tube which surrounds a solid copper wire that runs down the centre
Space between has a non-conducting material which makes them more impervious to outside noise

6. Communication Basics of Networks

7. Communication Basics of Networks
Fiber-optic cable: light is electromagnetic
Can transmit more information down a single strand
Each cable can send several thousand phone conversations or computer communication

8. Communication Basics of Networks
Wireless connections: the link is made using electromagnetic energy that goes through space instead of along wires or cables
Three commonly used types of wireless communications are
Infrared
Radio frequency
Microwave

9. Communication Basics of Networks
Infrared: commonly used in TV and VCR remote controls
Use infrared frequencies of electromagnetic radiation that behave much like visible light
Must be in the line of sight
Often used to connect wireless keyboards, mice and printers

10. Communication Basics of Networks
Radio frequency: uses radio frequencies (better as they can function without line of sight). Most commonly used in the home wireless setup and becoming increasingly popular around cities known as “hotspots”.

11. Communication Basics of Networks
Microwave: good for distant locations however still require line of sight so used for satellite communications

12. Communication Basics of Networks
Properties of Transmission: five basic properties of both the physical and wireless links:
Type of signal communicated (analog or digital)
The speed at which the signal is transmitted
The type of data movement allowed on the channel i.e. one way, two way simultaneously or two way taking turns

13. Communication Basics of Networks
4. The method used to transport the data i.e. asynchronous and synchronous transmission 5. Single channel (baseband) and multichannel (broadband) transmission

14. Communication Basics of Networks
A MODEM (Modulator Demodulator) converts telephone signals (analog) into binary data for the computer (digital) and vice–a- versa
Can be either external or internal