Question

Explain the basic elements of the communication system with the necessary block diagram.

Answer 1

1. Information (Baseband or input signal):

1. Information can be in the form of a sound signal like speech, music, pictures or computer data.
2. These can be given as input to the input transducer.

2. Input transducer:

1. It converts variation in a physical quantity such as pressure, temperature, sound into equivalent electrical signals or vice versa.
2. It converts the information into corresponding electrical signals.
3. The electrical equivalent of the original information is called the baseband signal.

3. Transmitter: It is located at the broadcasting station.

a) Amplifier: Very weak transducer output is amplified

b) Oscillator:

1. For long-distance, the high-frequency carrier wave is transmitted into space.
2. Energy of the wave is proportional to its frequency, so the carrier wave has very high energy.

c) Modulator: It superimposes the baseband signal onto the carrier signal and generates the modulated signal.

d) Power amplifier: To cover a large distance, the power level of the electrical signal is increased.

4. Transmitting antenna:

1. It travels in the form of electromagnetic waves with the velocity of light.
2. Used for long-distance transmission
3. Ex: Mobile, radio or TV broadcasting, satellite communication.

5. Communication channel: To carry the electrical signal from transmitter to receiver with less noise or distortion.

Wireline Communication:

1. Medium – Wires, Cables, and optical fibers
2. Cannot be used for long-distance transmission
3. Ex: Telephone, intercom and Cable TV

Wireless communication:

1. Medium – free space
2. Signals are transmitted in the form of electromagnetic waves.

6. Noise:

1. Undesirable electrical signal
2. Reduces the quality of the transmitted signal.
3. It may be man-made or natural.
4. It cannot be completely eliminated but it can be reduced.

7. Receiver:

1. The transmitted signals are fed into the receiver.
2. Receiver consists of the demodulator, amplifier, detector, etc.
3. Demodulator extracts the baseband signal from the carrier.
4. Then it is amplified and detected, then fed to the output transducer.

8. Repeaters:

1. Combination of transmitter and receiver
2. Increase the range or distance through which the signals are sent.
3. Signals are received, amplified, and retransmitted with a different frequency to the destination.
4. Ex. Communication satellite in space.

9. Output transducer:

1. Converts the electrical signal back to its original forms such as sound, music, pictures or data.
2. Ex : Loudspeakers, Picture tubes, Computer monitor, etc.

10. Attenuation: The loss of strength of a signal while propagating through a medium.

11. Range:

1. Maximum distance between the source and the destination.
2. The signal is received with sufficient strength.