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COMMUNICATION SYSTEMS
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COMMUNICATION SYSTEMS
Very Short Answer Questions
Q1. What are the basic blocks of a communication system?
Answer
Ans.
A communication system has 3 basic blocks.
1) Transmitter. 2) channel 3) Receiver
Q2. What is “world wide web (www)” ?
Answer
Ans.
It is an encyclopedia of knowledge accessible to everyone round the clock though out the year.
Q3. Mention the frequency range of speech waves.
Answer
Ans.
Frequency range of speech waves is from 300HZ to 3100 HZ
Q4. What is sky wave propagation?
Answer
Ans. Long distance communication can be achieved by ionosphere reflection of radio wavesback towards earth. This mode of propagation is called sky wave propagation. Frequency range: few MHz up to 30 to 40 MHz,
Q5. Mention the various parts of the ionosphere.
Answer
Ans.
1) D part of stratosphere
2) E part of stratosphere
3) F1 part of mesosphere
4) F2 part of thermosphere
Q6. Define modulation. Why is it necessary?
Answer
Ans. Modulation: The process of combing audio frequency signal with high frequency signal is called modulation.
Necessity:
1) to reduce size of antenna.
2) to increase effective radiated power by the antenna.
Q7. Mention the basic methods of modulation.
Answer
Ans. 1)Amplitude modulation
2)Frequency modulation
3) Phase modulation
Q8. Which type of communication is employed in mobile phones?
Answer
Ans. Space wave communication.
Q1. Draw the block diagram of a generalized communication system and explain it briefly.
Q2. What is a ground wave ?When is it used for communication?
Q3. What are Sky Waves? Explain Sky wave propagation, briefly.
Q4. What is Space Wave Communication? Explain.
Q5. What do you understand by modulation?Explain the need for modulation.
Q6. What should be the size of the antenna or aerial? How the power radiated is related to length of the antenna and wavelength?
Q7. Explain amplitude modulation.
Q8. How can an amplitude modulated wave be generated? How can an amplitude modulated wave be detected?