ISRO ICRB Scientist/Engineer 'SC' Electronics & Communication (ECE) ICRB Pattern

ISRO Scientist/Engineer ECE Solved Papers

Practice previous years' questions for Electromagnetics, Antennas, Microwave Engineering, Digital Communication, Signals & Systems, Analog Electronics, VLSI, and Optical Communications.

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Marking scheme: +3.00 positive, -0.75 negative (ICRB Standard).

50 Questions Page 1 of 2
1

Given that the following matrix is singular:

$$\begin{pmatrix} 4 & 2x & 0 \\ 4 & 0 & 2 \\ 12 & 6 & 0 \end{pmatrix}$$

The value of $x$ is:

ISRO Scientist/Engineer 'SC' ECE 2023 Engineering Mathematics
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2

Given that the Eigen values of matrix $A_{3 \times 3}$ are $1$, $3$, and $5$. The Eigen values of $A^3$ are:

ISRO Scientist/Engineer 'SC' ECE 2023 Engineering Mathematics
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3

$$\frac{d}{dx} \left( x - \frac{x^3}{3!} + \frac{x^5}{5!} - \frac{x^7}{7!} + \dots \right)$$

is equal to:

ISRO Scientist/Engineer 'SC' (Electronics) - 2023 Engineering Mathematics
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4

Value of the integral:

$$\int_{-\infty}^{\infty} \delta(t) \sin\left(\frac{t}{\sqrt{2}}\right) dt$$

is:

ISRO Scientist/Engineer 'SC' (Electronics) - 2023 Signals & Systems
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5

Which of the following statements is true?

ISRO Scientist/Engineer 'SC' (Electronics) - 2023 Signals & Systems
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6

If a random communication signal has PDF given by $P(X) = 2a e^{-b|x|}$ for all $x$, $-\infty < x < +\infty$, then:

ISRO Scientist/Engineer 'SC' (Electronics) - 2023 Communications & Probability
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7

The noise phenomena arranged in the order of their dominance when plotted as a function of increasing frequency are:

ISRO Scientist/Engineer 'SC' (Electronics) - 2023 Electronic Devices & Noise
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8

When a carrier is AM modulated by three single tone signals of modulation percentages $50\%$, $50\%$ and $20\%$, then the effective modulation index of the resulting signal is:

ISRO Scientist/Engineer 'SC' (Electronics) - 2023 Communications
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9

$8$ signals, each limited to $2\text{ kHz}$ and sampled at Nyquist rate, are converted into binary PCM signal using $256$ quantization levels. The data rate for TDM signal will be:

ISRO Scientist/Engineer 'SC' (Electronics) - 2023 Communications
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10

The bandwidth occupied by an 8 PSK modulated signal, where each of the I, Q and C data streams which form the n-tuple IQC toggle at a rate 200 Mbps, is:

ISRO Scientist/Engineer 'SC' (Electronics) - 2023 Communications
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11

Given that CNDR of 256 QAM signal operating at $12.5\text{ M Symbols/s}$ is $100\text{ dBHz}$. The value of $E_b/N_0$ (Energy-per-bit to Noise Density ratio) is:

ISRO Scientist/Engineer 'SC' (Electronics) - 2023 Communications
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12

Return loss of a stand-alone antenna is $10\text{ dB}$. One $6\text{ dB}$ attenuator with return loss of $40\text{ dB}$ is connected at the input of that antenna. What will be the approximate return loss of the combined (Antenna + Attenuator) port?

ISRO Scientist/Engineer 'SC' (Electronics) - 2023 Electromagnetics & Antennas
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13

Which parameter of semiconductor diode exhibits positive temperature co-efficient?

ISRO Scientist/Engineer 'SC' (Electronics) - 2023 Electronic Devices
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14

If a transistor operates at the middle of the dc load line, an increase in the current gain will move the Q point

ISRO Scientist/Engineer 'SC' (Electronics) - 2023 Analog Circuits
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15

The relation between $I_D$ and $V_{gs}$ of a MOSFET in the saturation region is

ISRO Scientist/Engineer 'SC' (Electronics) - 2023 Electronic Devices
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16

Which is the identity for convolution operation?

ISRO Scientist/Engineer 'SC' ECE 2023 Signals & Systems
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17

Random variable $x$ is with uniform distribution in the span $[-4, 1]$, mean and variance of $x$ is

ISRO Scientist/Engineer 'SC' ECE 2023 Engineering Mathematics
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18

Transfer function $H(s) = 1/(s + 3)^2$ has poles

ISRO Scientist/Engineer 'SC' ECE 2023 Control Systems
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19

An LTI system is minimum phase if

ISRO Scientist/Engineer 'SC' ECE 2023 Signals & Systems
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20

Given a real sequence and 8 point DFT output are $X(0) = 5,$ $X(1) = 1 + j,$ $X(2) = 3 + j,$ $X(3) = 2 + 3j$. What is $X(6)$?

ISRO Scientist/Engineer 'SC' ECE 2023 Digital Signal Processing
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21

Which of the following is NOT TRUE, given that “$\rightarrow$” represents fourier transform, “$*$” represents convolution, $x(n) \rightarrow X(e^{j\omega})$ and $y(n) \rightarrow Y(e^{j\omega})$?

ISRO Scientist/Engineer 'SC' ECE 2023 Signals & Systems
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22

The butterfly in the figure is taken from radix-2 decimation-in-time FFT with $N = 32$. Assume that the five stages of the signal flow graph are indexed by $m = 1, 2, 3, 4, 5,$ where $5$ is the last stage. Which of the five stages has butterflies of this form?

ISRO Scientist/Engineer 'SC' ECE 2023 Digital Signal Processing
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23

If A & B are 8-bit right shift registers connected such that the serial output of register A ($SO_A$) is connected to the serial input of register B ($SI_B$), and the serial output of register B ($SO_B$) is connected to the serial input of register A ($SI_A$), and the initial values of A & B in hexadecimal are $\text{B2}$ and $\text{0F}$ respectively, the value of A in hexadecimal after 6 clock pulses is:

ISRO Scientist/Engineer 'SC' ECE 2023 Digital Electronics
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24

What is the quantization noise power for $N$-bit uniform quantizer with full scale input voltage $2B$?

ISRO Scientist/Engineer 'SC' ECE 2023 Communications
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25

Simplified Boolean function $f(A, B, C, D) = \sum m(0, 2, 4, 5, 6, 7, 8, 10, 13, 15)$ in POS form is:

ISRO Scientist/Engineer 'SC' ECE 2023 Digital Electronics
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