Important RGPV Question
EC-403 (Analog Communication)
IV Sem, EC
UNIT-1 Frequency Domain Representation of Signal
Q.1Β Find the Fourier Transform of the following signals.
i) Sinusoidal
ii) Co-sinusoidal
iii) Signum
iv) Step
(RGPV Nov 2023)Β
Q.2Β Explain the significance of Auto correlation and Cross Correlation.
(RGPV Nov 2023)Β
Q.3Β Determine the Fourier transform of the damped sinusoidal waveform of frequency w shown in figure below.
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(RGPV June 2023)Β
Q.4Β What is a Gate function? Find the Fourier Transform of Gate-Function.
(RGPV June 2023)Β
Q.5Β State and prove the following properties of Fourier Transform.
i) Time shifting
ii) Frequency Shifting
(RGPV June 2023)Β
Q.6Β Write a short note on Convolution Theorem.
(RGPV June 2023)Β
Q.7Β Explain Fourier transform and its properties.
(RGPV Dec 2020)Β
Q.8Β Write about correlation (auto and cross), energy and power spectral density in detail.
(RGPV Dec 2020)Β
Q.9Β What is the Fourier transform of
i) Impulse function
ii) Step function
iii) Signum function
iv) Cosine function
v) Sine function
vi) Gate pulse
(RGPV June 2020)Β
Q.10Β Write properties of impulse function and convolution theorem (time and frequency).
(RGPV June 2020)Β
Q.11Β Determine the Fourier transform of following signals.
a) u(t)
b) Sgn (t)
c) e-1sin wt
d) s(t)
e) Gate pulse
(RGPV May 2019)Β
Q.12Β Write properties of impulse function and convolution theorem (time and frequency).
(RGPV June 2022)Β
Q.13Β What is a Gate function? Find the Fourier Transform of Gate-Function.
(RGPV June 2023)
UNIT β 2 Overview of Communication System
Q.1Β Explain the need for modulation.
(RGPV Nov 2023)Β
Q.2Β Discuss the generation and demodulation of AM signals.
(RGPV Nov 2023)Β
Q.3Β A carrier wave 4 sin (2Ο Γ 500 Γ 101) volts is amplitude modulated by an audio wave [ 0.2 sin(3(2Ο Γ 500t) + 0.1 sin 5(2Ο Γ 500t) ] volts. Determine the upper and lower side bands and sketch the complete spectrum of the modulated wave. Estimate the total power in the sideband.
(RGPV Nov 2023)Β
Q.4Β Explain about the COSTAS Loop with a neat diagram for the demodulation of DSB-SC waves.
(RGPV Nov 2023)Β
Q.5Β What is the principle of Amplitude modulation? Derive expression for the AM wave and draw its spectrum.
(RGPV June 2023)Β
Q.6Β Calculate the percentage power saving when the carrier and one of the sidebands are suppressed in an AM wave modulated to a depth of 100% and 50%.
(RGPV June 2023)Β
Q.7Β What is vestigial side band? Explain the process of generation and detection of VSB modulated wave using a carrier Ac Cos2ΟΒ fctΒ Β
(RGPV June 2023)Β
Q.8Β Explain about COSTAS loop with a neat block diagram for demodulating DSB-SC wave.
(RGPV June 2022)Β
Q.9Β With the help of circuit diagram explain the operation of square law modulator for AM.
(RGPV June 2022)Β
Q.10Β Explain the noise performance in DSB-SC system and obtain necessary expression for figure of merit.
(RGPV June 2023)Β
Q.11Β Write a short note on SSB-SC.
(RGPV June 2023)Β
Q.12Β Calculate the percentage power saving when the carrier and one of the sidebands are suppressed in an AM wave modulated to a depth of 100% and 50%.
(RGPV June 2022)Β
Q.13Β Differentiate A.M, DSB-SC and SSB-SC.
(RGPV June 2022)Β
Q.14Β Give the applications of AM-FC and VSB modulation schemes.
(RGPV June 2022)Β
Q.15Β What are the different elements in communication systems? Explain each block.
(RGPV Dec 2020)Β
Q.16Β Write the expression for DSB-SC signal. Describe synchronous detection.
(RGPV Dec 2020)Β
Q.17Β Describe figure of merit for DSB-SC, SSB and frequency modulation.
(RGPV Dec 2020)Β
Q.18Β Find the equation for VSB-SC signal. Draw the spectrum and find BW.
(RGPV Dec 2020)Β
Q.19Β Describe figure of merit for envelope detection, SSB, phase modulation.
(RGPV June 2020)Β
Q.20Β Find the equation for SSB-SC signal for tone modulation. Draw spectrum and find BW.
(RGPV June 2020)Β
Q.21Β Write short notes on (Any three)
a) Side tone
b) Channel
c) A.M.
d) VSB
(RGPV June 2020)Β
Q.22Β State and prove the following properties of Fourier transform.
a) Time shifting
b) Frequency shifting
c) Time differentiation
d) Time Integration
e) Convolution (time).
(RGPV May 2019)Β
Q.23Β What is Modulation? What is need for Modulation?
(RGPV May 2019)Β
Q.24Β Explain the method of generation of SSB-SC signal.
(RGPV May 2019)Β
Q.25Β Explain the phase discrimination method for generation of VSB-SC signal.
(RGPV May 2019)
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UNIT β 3 Types of Angle of ModulationsΒ
Q.1Β What is the difference between FM and PM? Explain the significance of pre-emphasis and de-emphasis.
(RGPV Nov 2023)Β
Q.2Β Explain the PLL method of detection of FM signals.
(RGPV Nov 2023)Β
Q.3Β Explain briefly about AGC and AFC.
(RGPV Nov 2023)Β
Q.4Β On an FM system, the modulating frequency is 1 kHz, its amplitude is 3V and deviation is 4 kHz.
i) If the modulating voltage is now increased to 5V, what is the new deviation?
ii) If the modulating voltage and frequency is increased to 10V and 400 Hz respectively, find the new deviation and modulation index.
(RGPV Nov 2023)Β
Q.5Β Discuss why FM is more immune to noise than AM systems?
(RGPV Nov 2023)Β
Q.6Β Discuss briefly about Narrow band FM and Wide band
(RGPV Nov 2023)Β
Q.7Β What are the different demodulation techniques of FM? Explain the demodulation of F.M signal with the help of PLL.
(RGPV June 2023)Β
Q.8Β What are the different demodulation techniques of FM? Explain the demodulation of F.M signal with the help of PLL.
(RGPV June 2023)Β
Q.9Β A carrier is frequency modulated by a sinusoidal signal of frequency 2 kHz resulting in a maximum frequency deviation of 6 kHz.
i) Calculate the modulation index and band width
ii) If the amplitude of the message signal is increased by a factor of 3 and its frequency is decreased to 2 kHz.
(RGPV June 2023)Β
Q.10Β Derive the expression and explain how pre-emphasis/de- emphasis filtering improves the signal to noise ratio?
(RGPV June 2023)Β
Q.11Β Write a short note on AFC
(RGPV June 2023)Β
Q.12Β An FM wave with modulation index αΊ= 1 is transmitted through an ideal band pass filter with mid band frequency fc and bandwidth is 5fm, where fc is the carrier frequency and fm is the frequency of the sinusoidal modulating wave. Determine the amplitude spectrum of the filter output.
(RGPV June 2022)Β
Q.13Β Explain the indirect method of generation of FM wave and any one method of demodulating an FM wave.
(RGPV June 2022)Β
Q.14Β Draw the block diagram of phase shift discriminator and explain the functionality of each block.
(RGPV June 2022)
Q.15Β Draw the block diagram of FM receiver and explain each block.
(RGPV June 2022)
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Q.16 Prove that narrowband FM offers no improvement in SNR over AM.
(RGPV June 2022)Β
Q.17Β For an FM modulator with a modulating signal m(t)= Vm sin(300Γ10ΒΉt), the carrier Signal V,(t)=8 sin (6.5Γ10t) and the modulator index = 2. Find out the significant side band frequencies and their amplitudes.
(RGPV June 2022)Β
Q.18Β Write the difference between A.M and F.M,
(RGPV Dec 2020)Β
Q.19Β Draw the block diagram of FM transmitter and explain it.
(RGPV Dec 2020)Β
Q.20Β Define AGC, AVC and AFC.
(RGPV Dec 2020)Β
Q.21Β What is the need for modulation? Describe baseband and passband signals with spectrum.
(RGPV June 2020)Β
Q.22Β What is side band in AM wave? How is it utilized in communication?
(RGPV June 2020)Β
Q.23Β Describe angle modulation and its types in detail.
(RGPV June 2020)Β
Q.24Β Describe narrowband FM and wideband FM in detail.
(RGPV June 2020)Β
Q.25Β Explain Narrow band frequency modulation.
(RGPV May 2019)Β
Q.26Β Explain about AGC and AFC.
(RGPV May 2019)Β
Q.27Β Determine the figure of merit of FM.
(RGPV May 2019)
UNIT β 4 AM Transmitter & ReceiverΒ
Q.1Β Draw a neat block diagram of a super-heterodyne receiver and explain its operation.
(RGPV Nov 2023)Β
Q.2Β Write a short note on the following
i) Image signal rejection
ii) Selectivity
(RGPV Nov 2023)Β
Q.3Β Write about image frequency and derive expression for the Image Frequency Rejection Ratio in radio receivers.
(RGPV June 2023)Β
Q.4Β An AM superhet receiver is tuned to 600 kHz, if the ‘Q’ of the RF amplifier tank circuit is 60 and the IF is 455 kHz. Find image frequency and its rejection ratio.
(RGPV June 2023)Β
Q.5Β With the aid of the block diagram explain TRF receiver. List out the advantages and disadvantages of TRF receiver.
(RGPV June 2023)Β
Q.6Β Of all the frequencies that must be rejected by a super heterodyne receiver, why is the image frequency so important? What is the image frequency and how does it arise? If the image-frequency rejection of a receiver is insufficient, what steps could be taken to improve it?
(RGPV June 2022)Β
Q.7Β The antenna current of an AM transmitter is 8 Amps, when only the carrier is sent, but it increases to 8.93 A, when the carrier is modulated by a single sine wave. Find percentage modulation. Determine the antenna current when the percent modulation changes to 0.8.
(RGPV June 2022)Β
Q.8 When a broadcast AM transmitter is 50 percent modulated, its antenna current is 12 A. What will be current when the modulation depth is increased to 0.9?
(RGPV June 2022)Β
Q.9Β Describe Noise in AM and image signal rejection.
(RGPV Dec 2020)Β
Q.10Β Explain super heterodyne receiver with block diagram.
(RGPV Dec 2020)Β
Q.11Β Describe direct and indirect methods of WBFM generation.
(RGPV June 2020)Β
Q.12Β Describe selectivity, sensitivity and fidelity of AM receivers.
(RGPV June 2020)Β
Q.13Β Explain tuned radio receiver and limitation of TRF.
(RGPV June 2020)Β
Q.14Β Explain the effects of noise on AM and FM receivers.
(RGPV June 2020)Β
Q.15Β Derive the expression of efficiency for AM modulated waveform.
(RGPV May 2019)Β
Q.16Β Explain the principle working of super heterodyne receiver.
(RGPV May 2019)Β
Q.17Β Explain the following.
i) Selectivity
ii) Sensitivity
iii) Fidelity
iv) Image signal rejection
(RGPV May 2019)
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UNIT β 5 NoiseΒ
Q.1Β Explain the different sources of noise.
(RGPV Nov 2023)Β
Q.2Β Explain the terms:
i) Noise figure
ii) Noise temperature
iii) Noise bandwidth
(RGPV Nov 2023)Β
Q.3 Define the following:
i) Noise figure
ii) Noise temperature
iii) Noise Bandwidth
iv) Noise figure measurement
(RGPV June 2023)Β
Q.4Β Write a short note on any two:
iv) Sources of Noise
(RGPV June 2023)Β
Q.5Β Define the following:
i) Noise figure
ii) Noise temperature
iii) Noise Bandwidth
iv) Noise figure measurement
(RGPV June 2022)Β
Q.6Β What is Noise? Write down the classification and sources of noise.
(RGPV Dec 2020)Β
Q.7Β Describe noise in AM and F.M.
(RGPV Dec 2020)Β
Q.8Β Define the following:
i) Noise figure
ii) Noise temperature
iii) Noise Bandwidth
iv) Noise figure measurement
(RGPV June 2020)Β
Q.9Β Classify types of Noise and sources of Noise.
(RGPV May 2019)
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— Best of Luck for Exam —
