GATE ECE kind:question PYQs & Answers — Page 69

Questions 681–690 of 715. Imported answers require independent review unless marked reviewed.

A unity feedback control system is characterized by the open-loop transfer function

. The Nyquist path and the corresponding Nyquist plot of

are shown in the figures below.

Diagram for Electronics and Communication Engineering question 48

, then the number of poles of the closed-loop transfer function that lie in the right-half of the

-plane is

Your answerChoose one option.

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The Nyquist plot of the transfer function

does not encircle the point

for

but does encircle the point

for

. Then the closed loop system (having unity gain feedback) is

Your answerChoose one option.

stable for

and stable for

stable for

and unstable for

unstable for

and stable for

unstable for

and unstable for

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The signal

, where

is in seconds, is sampled at a rate of 9000 samples per second. The sampled signal is the input to an ideal lowpass filter with frequency response

as follows:

What is the number of sinusoids in the output and their frequencies in kHz?

Your answerChoose one option.

Number = 1, frequency = 7

Number = 3, frequencies = 2, 7, 11

Number = 2, frequencies = 2, 7

Number = 2, frequencies = 7, 11

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In binary frequency shift keying (FSK), the given signal waveforms are

, and

, where

is the bit-duration interval and

is in seconds. Both

and

are zero outside the interval

. With a matched filter (correlator) based receiver, the smallest positive value of

(in milliseconds) required to have

and

uncorrelated is

Your answerChoose one option.

0.25 ms

0.5 ms

0.75 ms

1.0 ms

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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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Let

be a wide sense stationary random process with the power spectral density

as shown in Figure (a), where

is in Hertz (Hz).

Diagram for Electronics and Communication Engineering question 51

The random process

is input to an ideal lowpass filter with the frequency response

as shown in Figure (b).

Diagram for Electronics and Communication Engineering question 51 (figure 2)

The output of the lowpass filter is

Let

be the expectation operator and consider the following statements:

II.

III.

Select the correct option:

Your answerChoose one option.

only I is true

only II and III are true

only I and II are true

only I and III are true

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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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A continuous time signal

, where

is in seconds, is the input to a linear time invariant (LTI) filter with the impulse response

Let

be the output of this filter. The maximum value of

is ________.

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Consider a binary memoryless channel characterized by the transition probability diagram shown in the figure.

Diagram for Electronics and Communication Engineering question 52

The channel is

Your answerChoose one option.

lossless

noiseless

useless

deterministic

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An optical fiber is kept along the

direction. The refractive indices for the electric fields along

and

directions in the fiber are

and

, respectively (

due to the imperfection in the fiber cross-section). The free space wavelength of a light wave propagating in the fiber is 1.5

m. If the lightwave is circularly polarized at the input of the fiber, the minimum propagation distance after which it becomes linearly polarized, in centimetres, is ________.

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GATE ECE kind:question PYQs

Question 48

Question 49

Question 49

Question 50

Question 50

Question 51

Question 51

Question 52

Question 52

Question 53