Code No: RR311202 RR Set No. 2
III B.Tech I Semester Supplementary Examinations,June 2010
COMMUNICATION THEORY Information Technology
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) What is the need for modulation? Derive the relation between the ouput power of an AM transmitter and depth of modulation. Give output power in case of critical modulation.
(b) The ouput RMS current of 60% modulated AM generator is 1.5 A. To what values will this current rise if the generator is modulated additionally, by an- other audio wave whose modulation index is 0.7? What will be the percentage power saving if the carrier and one of the side bands are now suppressed?[8+8]
2. (a) Explain the principle of balanced frequency discriminator with its diagram. (b) A sinusoidal modulating wave of amplitude 10v, and frequency 5KHz is ap-
plied to a frequency modulator. The frequency sensitivity of the modulator
is 45Hz/v, the carrier frequency is 150KHz. Calculate its frequency deviation and modulation index.
(c) Show that the average power of FM is constant. [8+4+4]
3. (a) Derive an expression for source entropy. Obtain the condition for maximum entropy.
(b) A discrete source emits one of 5 symbols once every milli second. The symbol probabilities are 0.4, 0.2, 0.15,0.15, 0.1 respectively. Determine the source entropy and information rate. [12+4]
4. (a) With reference to coding techniques, define and explain the following terms:
i. systematic code
ii. parity check matrix
iii. syndrome .
(b) Classify the different types of error control coding techniques, and distinguish between them. [8+8]
5. (a) Explain the basic properties of convolution operator.
(b) Derive Parseval's theorem. [8+8]
6. (a) Give the block diagram of DM and explain clearly the procedure for generation and demodulation of delta modulated signals.
(b) What are the various types of errors that occur in delta modulation? Explain how they can be minimized. [10+6]
7. (a) Find the autocorrelation of a non- periodic waveform of finite energy.
1
Code No: RR311202 RR Set No. 2
(b) Prove the following properties of auto correlation function, RX X (τ ) for com- plex signal x(t)
i. RX X (0) ≥ | RX X (τ )|
ii. R∗
(τ ) = RX X (-τ ) [8+8]
8. (a) State and prove sampling theorem in case of low pass signals.
(b) If a signal is naturally sampled with a sample width z and with frequency ws
rad/sec. Obtain the expression for Bandwidth. [8+8]
? ? ? ? ?
2
Code No: RR311202 RR Set No. 4
III B.Tech I Semester Supplementary Examinations,June 2010
COMMUNICATION THEORY Information Technology
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Find the autocorrelation of a non- periodic waveform of finite energy.
(b) Prove the following properties of auto correlation function, RX X (τ ) for com-
plex signal x(t)
i. RX X (0) ≥ | RX X (τ )|
ii. R∗
(τ ) = RX X (-τ ) [8+8]
2. (a) Explain the principle of balanced frequency discriminator with its diagram.
(b) A sinusoidal modulating wave of amplitude 10v, and frequency 5KHz is ap- plied to a frequency modulator. The frequency sensitivity of the modulator is 45Hz/v, the carrier frequency is 150KHz. Calculate its frequency deviation and modulation index.
(c) Show that the average power of FM is constant. [8+4+4]
3. (a) With reference to coding techniques, define and explain the following terms:
i. systematic code
ii. parity check matrix iii. syndrome .
(b) Classify the different types of error control coding techniques, and distinguish between them. [8+8]
4. (a) State and prove sampling theorem in case of low pass signals.
(b) If a signal is naturally sampled with a sample width z and with frequency ws
rad/sec. Obtain the expression for Bandwidth. [8+8]
5. (a) Derive an expression for source entropy. Obtain the condition for maximum
entropy.
(b) A discrete source emits one of 5 symbols once every milli second. The symbol probabilities are 0.4, 0.2, 0.15,0.15, 0.1 respectively. Determine the source entropy and information rate. [12+4]
6. (a) Give the block diagram of DM and explain clearly the procedure for generation and demodulation of delta modulated signals.
(b) What are the various types of errors that occur in delta modulation? Explain how they can be minimized. [10+6]
7. (a) Explain the basic properties of convolution operator.
3
Code No: RR311202 RR Set No. 4
(b) Derive Parseval's theorem. [8+8]
8. (a) What is the need for modulation? Derive the relation between the ouput power of an AM transmitter and depth of modulation. Give output power in case of critical modulation.
(b) The ouput RMS current of 60% modulated AM generator is 1.5 A. To what values will this current rise if the generator is modulated additionally, by an- other audio wave whose modulation index is 0.7? What will be the percentage power saving if the carrier and one of the side bands are now suppressed?[8+8]
? ? ? ? ?
4
Code No: RR311202 RR Set No. 1
III B.Tech I Semester Supplementary Examinations,June 2010
COMMUNICATION THEORY Information Technology
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Explain the principle of balanced frequency discriminator with its diagram. (b) A sinusoidal modulating wave of amplitude 10v, and frequency 5KHz is ap-
plied to a frequency modulator. The frequency sensitivity of the modulator
is 45Hz/v, the carrier frequency is 150KHz. Calculate its frequency deviation and modulation index.
(c) Show that the average power of FM is constant. [8+4+4]
2. (a) State and prove sampling theorem in case of low pass signals.
(b) If a signal is naturally sampled with a sample width z and with frequency ws
rad/sec. Obtain the expression for Bandwidth. [8+8]
3. (a) Derive an expression for source entropy. Obtain the condition for maximum entropy.
(b) A discrete source emits one of 5 symbols once every milli second. The symbol probabilities are 0.4, 0.2, 0.15,0.15, 0.1 respectively. Determine the source entropy and information rate. [12+4]
4. (a) Give the block diagram of DM and explain clearly the procedure for generation and demodulation of delta modulated signals.
(b) What are the various types of errors that occur in delta modulation? Explain
how they can be minimized. [10+6]
5. (a) Explain the basic properties of convolution operator.
(b) Derive Parseval's theorem. [8+8]
6. (a) What is the need for modulation? Derive the relation between the ouput power of an AM transmitter and depth of modulation. Give output power in case of critical modulation.
(b) The ouput RMS current of 60% modulated AM generator is 1.5 A. To what values will this current rise if the generator is modulated additionally, by an- other audio wave whose modulation index is 0.7? What will be the percentage power saving if the carrier and one of the side bands are now suppressed?[8+8]
7. (a) Find the autocorrelation of a non- periodic waveform of finite energy.
(b) Prove the following properties of auto correlation function, RX X (τ ) for com- plex signal x(t)
i. RX X (0) ≥ | RX X (τ )|
5
Code No: RR311202 RR Set No. 1
ii. R∗
(τ ) = RX X (-τ ) [8+8]
8. (a) With reference to coding techniques, define and explain the following terms:
i. systematic code
ii. parity check matrix iii. syndrome .
(b) Classify the different types of error control coding techniques, and distinguish between them. [8+8]
? ? ? ? ?
6
Code No: RR311202 RR Set No. 3
III B.Tech I Semester Supplementary Examinations,June 2010
COMMUNICATION THEORY Information Technology
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Derive an expression for source entropy. Obtain the condition for maximum
entropy.
(b) A discrete source emits one of 5 symbols once every milli second. The symbol probabilities are 0.4, 0.2, 0.15,0.15, 0.1 respectively. Determine the source entropy and information rate. [12+4]
2. (a) With reference to coding techniques, define and explain the following terms:
i. systematic code
ii. parity check matrix iii. syndrome .
(b) Classify the different types of error control coding techniques, and distinguish
between them. [8+8]
3. (a) Find the autocorrelation of a non- periodic waveform of finite energy.
(b) Prove the following properties of auto correlation function, RX X (τ ) for com-
plex signal x(t)
i. RX X (0) ≥ | RX X (τ )|
ii. R∗
(τ ) = RX X (-τ ) [8+8]
4. (a) Explain the principle of balanced frequency discriminator with its diagram. (b) A sinusoidal modulating wave of amplitude 10v, and frequency 5KHz is ap-
plied to a frequency modulator. The frequency sensitivity of the modulator
is 45Hz/v, the carrier frequency is 150KHz. Calculate its frequency deviation and modulation index.
(c) Show that the average power of FM is constant. [8+4+4]
5. (a) State and prove sampling theorem in case of low pass signals.
(b) If a signal is naturally sampled with a sample width z and with frequency ws
rad/sec. Obtain the expression for Bandwidth. [8+8]
6. (a) What is the need for modulation? Derive the relation between the ouput power of an AM transmitter and depth of modulation. Give output power in case of critical modulation.
(b) The ouput RMS current of 60% modulated AM generator is 1.5 A. To what values will this current rise if the generator is modulated additionally, by an- other audio wave whose modulation index is 0.7? What will be the percentage power saving if the carrier and one of the side bands are now suppressed?[8+8]
7
Code No: RR311202 RR Set No. 3
7. (a) Give the block diagram of DM and explain clearly the procedure for generation and demodulation of delta modulated signals.
(b) What are the various types of errors that occur in delta modulation? Explain how they can be minimized. [10+6]
8. (a) Explain the basic properties of convolution operator.
(b) Derive Parseval's theorem. [8+8]
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