1. CHAPTER Communication Direction, Bandwidth and Channels

2. Frequency Spectrum and Bandwidth
Chapter
Frequency Spectrum and Bandwidth

3. Chapter Objectives
Explain the different types of directional flows in signal propagation
Define bandwidth and the use of the terminology in communications
Discuss communication channels and the splitting of bandwidth to accommodate multiple channels
Describe baseband and broadband transmission and present practical examples in each case

4. Chapter Objectives (continued)
Discuss communication channels and the splitting of bandwidth to accommodate multiple channels
Describe baseband and broadband transmission and present practical examples in each case

5. Chapter Modules Direction of communication Communication channels
Baseband and broadband channels

6. Direction of Communication
MODULE
Direction of Communication

7. Direction Of Flow
Simplex A B
Half-duplex
Full-duplex

8. Direction Of Flow Details
Simplex
One direction only
Radio broadcast
Half-duplex
One direction at any one point in time
CB radio
Full duplex
Both directions at the same time
Telephone lines

9. END OF MODULE

10. The Concepts of Channels in Communication
MODULE
The Concepts of Channels in Communication

11. A Definition of a Communication Medium
One that allows the propagation of information carried by either electromagnetic or optical signals

12. Types of Media Physical medium and the space or open medium
Also know as the guided medium
Coaxial cable, Optical fiber etc.
Open Medium
Denotes the space above the earth
The term space is galactic in scope
Multiple channels can be established in each of these media for communication

13. Presence of Multiple Channels in a Physical Media
Guard Band
Channel 1
Frequency F1
Channel 2
Frequency F2
One physical medium (Coaxial cable).

14. Channel Characteristics
A sub-bandwidth is assigned for each channel for communication
Channel differentiation
Each channel transmits using a different frequency
The transmission frequency chosen for a channel is usually near the middle of the assigned bandwidth for the channel
Guard bands are present around each channel to minimize interference

15. Low and High-speed Channels in Medium
Guard Bands
5 Mhz
Channel 1
50 Mhz
10 Mhz
Channel 2
150 Mhz
5 Mhz
One cable with a bandwidth of 220 MHz.

16. Channel Characteristics of the Example
Channel speeds within a medium need not be the same
Channel 2 in the previous example is faster than channel 1
Channel 2 speed is Proportional to 150 Hz
Channel 1 speed is Proportional 50 Hz
Total bandwidth of the medium is computed as follows:
=220 MHz

17. An Example of Multiple Channels in a Physical Medium
Cable TV (carries multiple channels)
TV 3
TV 1
TV 2
Tuned to
Channel 77 at
Frequency f77
Tuned to
Channel 33 at
Frequency f33
Tuned to
Channel 65 at
Frequency f65

18. An Example of Multiple Channel Communication in Space
At freq.. F4
TV1
Regular TV
Transmission
TV2
Channel 11
At freq.. F11
Transmission
Towers

19. END OF MODULE

20. Baseband and Broadband Transmission
MODULE
Baseband and Broadband Transmission

21. Baseband Transmission
Single channel transmission
The physical medium carries one and only one channel
A good example is the LAN
Ethernet LAN for instance uses baseband transmission

22. Broadband Transmission
The presence of Multiple channels over a single physical medium
One physical line is shared by multiple channels
Cable TV
Internet
Due to packet switching, one is given the impression of the presence of multiple channels
Virtual broadband communication

23. END OF MODULE

24. MODULE
Frequency Spectrum

25. Frequency Spectrum Spectrum of frequencies available for communication
Ranges from voice to high speed optical communication

26. END OF MODULE

27. END OF CHAPTER