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Tuesday, August 6, 2013

PPT On Communication System


Communication System Presentation Transcript:
1.A Communication System

2.A Communication System
Purpose of a communication system:
  -Carry information from one point to another
A typical communication system consists of three main components

3.How to build it ?

4.Basic Block Diagram of communication System

5.Channel Impairments
Acts as a filter to attenuate signal and distort the waveform
Signal attenuation increases with length of channel.

6.Channel Impairments
-Reduction in signal strength during transmission

7.Attenuation can be problematic for long distance communication.

8.Solution to Attenuation
Use Amplifiers
Use channels with smaller attenuation level (e.g. optical fiber)- such channels are usually expensive.

9.Channel Impairments
Un-desirable random and unpredictable signals due to external and internal sources.
-External Sources:
Interference from signals transmitted on nearby channels (crosstalk), interference generated by contact switches, natural noise from lightening, solar radiations etc.

10.Example: External Noise

Internal Sources
Thermal noise (random motion of electrons in conductors)

12.Noisy Signals are not desired!!!!!
The effect of external noise can be minimized or eliminated.
The effect of internal noise can be minimized but never eliminated.

13.Noise Elimination
Solution to external noise
Proper design of channel
Using LPF and BPF at receiver side.
Using digital transmission
Solution to internal Noise:
Using LPF and BPF at receiver side.

14.Impairments all together

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