JNTU
JNTU B.Tech III PRINCIPLES OF ELECTRONIC COMMUNICATIONS Previous Question Paper (May/June - 2019 - R16)
Note: This question paper contains two parts A and B. 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
The signal power at the input to a receiver is 6.2 nW and the noise power at the input to that receiver is 1.8 nW. Find SNR and SNRdB.
Answer
Given signal power S = 6.2 nW and noise power N = 1.8 nW. The Signal-to-Noise Ratio (SNR) is calculated as S/N = 6.2 / 1.8 ≈ 3.44. The SNR in decibels is calculated as SNRdB = 10 log10(3.44) ≈ 5.37 dB.
Define modulation and classify?
Answer
Modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a modulating signal that contains information to be transmitted. It is classified into: 1) Analog Modulation (e.g., AM, FM, PM) where the modulating signal is continuous, and 2) Digital Modulation (e.g., ASK, FSK, PSK) where the modulating signal is discrete.
Mention any two differences between ASK and FSK.
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An FM wave is given by s(t)=20cos(8π×10^6t+9sin(2π×10^3t)). Calculate the frequency deviation, bandwidth, and power of FM wave.
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Mention the advantages of LAN.
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Discuss briefly about local loop in telephones.
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What is trilateration principle?
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Mention the differences between LEDs and laser diodes with respect to performance characteristics.
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What are the functions of Mobile Station?
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Discuss about infrared wireless technology.
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Part B
Define the terms Gain, attenuation and decibels. And explain their importance in communications, with examples.
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Illustrate electromagnetic spectrum and clearly indicate all the bands.
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A power amplifier with a 40 dB gain has an output power of 100 W. What is the input power in dBs and in normal units?
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Define PWM and explain the modulation process with neat diagram.
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A sinusoidal modulating waveform of amplitude 5 V and a frequency of 2 KHz is applied to FM generator, which has a frequency sensitivity of 40 Hz/volt. Calculate the frequency deviation, modulation index, and bandwidth.
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Define ASK and describe the modulation process with neat diagram.
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Explain the frequency discrimination method of FM demodulation.
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Explain about electronic telephones.
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Describe Internet Telephony.
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Discuss briefly about LAN hardware.
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Discuss about Ethernet LANs in detail.
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Explain about satellite sub systems.
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Describe the process for determining look angle.
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Describe the operation and application of laser diodes.
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Discuss the differences between the various types of optical detectors with respect to performance characteristics.
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Draw and explain GSM architecture in detail.
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Write short notes on the following.
RFID communication
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UWB.
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