JNTU
JNTU B.Tech III PRINCIPLES OF COMMUNICATIONS Previous Question Paper (May/June - 2019 - R13)
Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks.
Part A
Define terms (i) line communication (ii) Radio communication.
Answer
(i) Line communication refers to the transmission of information signals over physical media such as copper wires, twisted pairs, coaxial cables, or optical fibers. (ii) Radio communication involves the transmission of signals through free space using electromagnetic waves without the need for physical conductors.
List the radio frequency bands and give frequency range of each band.
Answer
| Band | Frequency Range |
| VLF | 3 - 30 kHz |
| LF | 30 - 300 kHz |
| MF | 300 kHz - 3 MHz |
| HF | 3 - 30 MHz |
| VHF | 30 - 300 MHz |
| UHF | 300 MHz - 3 GHz |
| SHF | 3 - 30 GHz |
| EHF | 30 - 300 GHz |
What is the modulation index of AM? List any two effects it.
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Explain any one of wideband generation methods briefly.
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What are the various quantization errors?
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Briefly explain Asynchronous Multiplexing.
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What is the difference between delta modulation and adaptive delta modulation?
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Distinguish PSK and FSK.
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List different error correction and detection codes.
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Write briefly optimum rate of information.
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Part B
Define noise figure, derive expression for noise figure in terms of Signal to Noise ratio.
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Compare different types of Communications.
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Explain power density spectrum of shot noise in diodes, give its bandwidth.
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Derive expression for overall noise figure and overall noise temperature of a cascaded amplifier.
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What are the advantages of FM over AM?
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When the modulating frequency in a FM system is 400 Hz and the modulating voltage is 2.4 V, the modulating index is 60. Calculate maximum frequency deviation. What is the modulation index when modulating frequency is 250 Hz and modulating voltage is 3.2 V.
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Explain the principle of angle modulation, derive expression for phase deviation, modulation index and percentage modulation.
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Describe detection of DSBSC Signal.
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Define multiplexing and briefly explain TDMA system with suitable diagrams.
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State and prove sampling theorem.
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Define Pulse modulation and explain generation and demodulation of PWM.
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Compare PAM, PWM and PPM systems.
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Explain what are the functions of Modems in communication and describe its working principle.
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Describe DPSK modulation and demodulation with suitable block diagrams.
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Discuss the principle of operation of ASK generation and ASK demodulation.
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What are the applications of PCM systems and explain any two applications in detail.
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Define parity check bit coding. How it is used for error detection and correction? Explain.
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Derive Shannon limit for information capacity.
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Consider a source with M=3 and symbol probability 0.6, 0.3 and 0.1. Obtain Shannon Fano Code and calculate its efficiency.
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Explain the encoding of convolution codes.
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