GATE ECE topic:analog-communications PYQs & Answers — Page 2

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topic:analog-communications

Questions 11–17 of 17. Imported answers require independent review unless marked reviewed.

Topic practice 17 questionsPage 2 of 2

S_PM(t) and S_FM(t) as defined below, are the phase modulated and the frequency modulated waveforms, respectively, corresponding to the message signal m(t) shown in the figure.

and

where K_p is the phase deviation constant in radians/volt and K_f is the frequency deviation constant in radians/second/volt. If the highest instantaneous frequencies of S_PM(t) and S_FM(t) are same, then the value of the ratio K_p/K_f is ______ seconds.

Diagram for Electronics and Communication Engineering question 47

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The baseband signal

shown in the figure is phase-modulated to generate the PM signal

. The time

on the x-axis in the figure is in milliseconds. If the carrier frequency is

kHz and

, then the ratio of the minimum instantaneous frequency (in kHz) to the maximum instantaneous frequency (in kHz) is _____ (rounded off to 2 decimal places).

Diagram for Electronics and Communication Engineering question 22

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A voice signal

is in the frequency range 5 kHz to 15 kHz. The signal is amplitude-modulated to generate an AM signal

, where

kHz. The AM signal

is to be digitized and archived. This is done by first sampling

at 1.2 times the Nyquist frequency, and then quantizing each sample using a 256-level quantizer. Finally, each quantized sample is binary coded using

bits, where

is the minimum number of bits required for the encoding. The rate, in Megabits per second (rounded off to 2 decimal places), of the resulting stream of coded bits is ______ Mbps.

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Consider the following amplitude modulated signal:

The ratio (accurate to three decimal places) of the power of the message signal to the power of the carrier signal is __________.

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Let

and

. It is given that

. The signal

is applied to the input of a non-linear device, whose output

is related to the input

, where a and b are positive constants. The output of the non-linear device is passed through an ideal band-pass filter with center frequency

and bandwidth

, to produce an amplitude modulated (AM) wave. If it is desired to have the sideband power of the AM wave to be half of the carrier power, then a/b is

Your answerChoose one option.

0.25

0.5

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The unmodulated carrier power in an AM transmitter is 5 kW. This carrier is modulated by a sinusoidal modulating signal. The maximum percentage of modulation is 50%. If it is reduced to 40%, then the maximum unmodulated carrier power (in kW) that can be used without overloading the transmitter is __________

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A modulating signal given by

V is fed to a phase modulator with phase deviation constant

rad/V. If the carrier frequency is 20 kHz, the instantaneous frequency (in kHz) at

ms is __________

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GATE ECE topic:analog-communications PYQs

Question 47

Question 22

Question 46

Question 15

Question 27

Question 50

Question 51