1. Subject: Information Technology Grade: 9
Topic: Data Communication

2. What is Communication?

3. What is Communication? What is Data?
Communication is the process by which we assign and convey meaning in an attempt to create shared understanding.
What is Data?
Data refers to raw facts, concepts or instructions.

4. Data Communication
Data Communication is the transmission of data (raw facts, concepts, or instructions) from one location to the other in order to enable communication (create a shared understanding) between locations.

5. Data Communication

6. Telecommunication
Telecommunication is the process of exchanging data or information from one location to another electronically.
Electronic systems include telegraph, cable, telephone, radio, or television

7. Data Communication Channels
The data is transmitted via data communication channels.
These channels are categorized according to their:
transmission speed (bandwidth)
direction of data flow (communication system directions)
transmission/communication modes

8. Categories of Bandwidth
Bandwidth is the amount of data that can be transmitted through the channel each second
Categories of Bandwidth
Narrow-band
Voice-band
Broad-band

9. Narrow-band Voice-band Broad-band
Data is transmitted at a slow speed (just over 10 characters each second), for example – telegraphed transmission.
Voice-band
Telephone lines are used, allowing data to be transmitted at a rate of up to 800 characters per second.
Broad-band
Broad-band uses fiber-optic cables, microwave and satellite transmission to allow very fast transmission of data (hundreds of thousands of characters per second).

10. Communication System Directions
There are various types of communication system that vary according to the direction in which data is transmitted. These are:
Simplex – Data can be transmitted in only one direction. Examples are radio and TV
Half-Duplex – Data can be transmitted in both direction, but not at the same time. Examples are CB radio and walkie-talkie
Duplex (Full Duplex) – Data can be transmitted in both direction at the same time. Examples are telephones, mobile phones and sending data via the internet.

11. Communication Media Types of Communication Media Wire Optical Wireless
Communication media (or transmission media) are the storage and transmission tools used to store and deliver information or data.
Types of Communication Media
Wire
Optical
Wireless