ISRO Scientist or Engineer Electronics 2014

ISRO Scientist or Engineer Electronics 2014 - Question 1

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In the circuit shown below, switch S1 and S2 are in open and close position respectively for long time. At $$t = t_o$$, switch S1 is closed and switch S2 is opened. What would be the current through R1 immediately after the transition of switches?

A

0 mA

B

1 mA

C

0.5 mA

D

2 mA

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ISRO Scientist or Engineer Electronics 2014 - Question 2

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A digital board has a unipolar square clock of 250MHz. If the clock on the board at all places should have all the harmonic components which have more than 10% of DC value, the board has to be designed forat least

A

250 MHz

B

750 MHz

C

1250 MHz

D

2500 MHz

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ISRO Scientist or Engineer Electronics 2014 - Question 3

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A switch is connected in between a 12V battery and an uncharged capacitor and a 1 KΩ resistor. At the time instant when the switch is closed, the voltage across the capacitor is:

A

6 V

B

12 V

C

0 V

D

24 V

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ISRO Scientist or Engineer Electronics 2014 - Question 4

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Which type of timing violation will occur, If a digital IC is operated at clock frequency which is higher than its specified maximum clock frequency?

A

Hold violation

B

Setup violation

C

Propagation delay

D

All of above

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ISRO Scientist or Engineer Electronics 2014 - Question 5

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If the maximum effective aperture of a radiating small loop of constant current is $$\left(\frac{3}{32 \pi}\right) m^2$$, the wavelength of the radiated electromagnetic wave is:

A

5000 mm

B

100 mm

C

1000 mm

D

500 mm

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ISRO Scientist or Engineer Electronics 2014 - Question 6

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A radar system uses magnetron as high power RF source. Its transmitter emits 300kW RF power at 10% duty factor. If the efficiency of radar transmitter during pulse is 60% and the power required during pulse off period is 1 kW..The average power dissipation in radar is,

A

50.9 kW

B

301 kW

C

20.9 kW

D

150.5 kW

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ISRO Scientist or Engineer Electronics 2014 - Question 7

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Match the following:

A

A-3, B-1, C-4, D-2

B

A-3, B-4, C-2, D-1

C

A-1, B-4, C-3, D-2

D

A-3, B-4, C-1, D-2

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ISRO Scientist or Engineer Electronics 2014 - Question 8

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In a fiber-optic cable, which phenomenonoccursfor signal to propagate along the inner core:

A

Modulation

B

Reflection

C

Refraction

D

All of the above

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ISRO Scientist or Engineer Electronics 2014 - Question 9

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Which of the following computation will take minimum number of clock cycles, if it is implemented on 8051 micro-controller? Following is variable declaration in c code:
unsigned int a, b;

A

$$b = a * a$$

B

$$b = a * 3$$

C

$$b = \frac{a}{3}$$

D

$$b = \frac{a}{4}$$

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ISRO Scientist or Engineer Electronics 2014 - Question 10

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Using a quarter wave transformer of characteristic impedance 1 Ω, a load impedance of 100 Ω will be transformed to an input impedance of value:

A

1 Ω

B

100 Ω

C

0.01 Ω

D

0.1 Ω

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ISRO Scientist or Engineer Electronics 2014 - Question 11

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What is the output signal level of following circuit?

A

~5 Vrms

B

~1 Vrms

C

~4 Vrms

D

~0.1 Vrms

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ISRO Scientist or Engineer Electronics 2014 - Question 12

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The effect of channel coding in communication channels is :

A

Reduced errors

B

Increased bandwidth

C

Reduced terminal size

D

All of above

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ISRO Scientist or Engineer Electronics 2014 - Question 13

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For a point charge having electric flux density, $$D = \frac{Q}{4 \pi r^2}a_r$$, where $$a_r$$ is the unit vector in radio direction; volume charge density $$\rho_v$$ is:

A

1

B

0

C

Infinite

D

$$\frac{Q}{4 \pi}$$

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ISRO Scientist or Engineer Electronics 2014 - Question 14

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What is Discrete Time Fourier Transform (DTFT) of following signal?
$$x(n) = a^n$$ where $$n \geq 0, -1 < a < 1$$

A

$$X(\omega) = \frac{1}{(1 - ae^{-j \omega})}$$

B

$$X(\omega) = \frac{1}{(1 + ae^{-j \omega})}$$

C

$$X(\omega) = \frac{a}{(1 - ae^{-j \omega})}$$

D

$$X(\omega) = \frac{a}{(1 + ae^{-j \omega})}$$

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ISRO Scientist or Engineer Electronics 2014 - Question 15

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In the near field, the radiated wavestake the form of :

A

Spherical Wave

B

Plane Wave

C

Cylindrical Wave

D

Conical Wave

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ISRO Scientist or Engineer Electronics 2014 - Question 16

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The zener diode shown in following figure is temperature compensated and current gain $$\beta$$ of transistor is very high. If current through 100 ohm resistor is 55mA at $$25^\circ C$$, what is the approximate current throughit at $$65^\circ C$$?

A

55 mA

B

54 mA

C

56 mA

D

100 mA

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ISRO Scientist or Engineer Electronics 2014 - Question 17

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Wewish to transmit a digital voice at 32 Kbps through a communication channel having bandwidth of 3000 Hz. The received signal to noise powerratio is 30 dB. State which of the following statementis true :

A

To transmit data error-free through this channel, channel equalizer circuit should be used at the receiver.

B

To transmit data error-free through this channel, the voice signal should be compressed by 2

C

Totransmit data error-free through this channel, a channel code with coding gain of 3 dB should be used.

D

It is not possible to transmit data error-free through this channel.

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ISRO Scientist or Engineer Electronics 2014 - Question 18

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Consider a standard rectangular and a circular waveguide having same dominant mode cut-off frequency, determine the ratio of area of circular waveguide to rectangular waveguide:

A

$$\frac{1}{\pi}$$

B

$$\frac{6.78}{\pi}$$

C

$$\frac{0.69}{\pi}$$

D

$$\pi$$

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ISRO Scientist or Engineer Electronics 2014 - Question 19

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What is the lowest level of abstraction in any hardware description language?

A

Behavioral

B

Gate level

C

Structural

D

Register-Transfer Level

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ISRO Scientist or Engineer Electronics 2014 - Question 20

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With the introduction of negative feedback, the gain-bandwidth product of an amplifier

A

Becomes infinity

B

Increases

C

Decreases

D

Remains constant

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ISRO Scientist or Engineer Electronics 2014 - Question 21

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For a BER of $$10^{-5}$$, which modulation schemewill require minimal power?

A

QPSK

B

8-PSK

C

16-PSK

D

16-QAM

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 22

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Which one of following is not synthesizable VHDL statement?

A

‘case’

B

‘wait until’

C

‘wait for’

D

generate

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ISRO Scientist or Engineer Electronics 2014 - Question 23

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Subsystem A requires two voltages V1 and V2 with equal power ratings. Power conversion scheme adapted for the power supply design is shown in the following figure. Whatis the overall power conversion efficiency?

A

$$\frac{(1 * (2}{(1 + (2}$$

B

$$\eta 1 * \eta 2$$

C

$$\frac{2(1 * (2}{1 + (2}$$

D

$$\frac{2(1 * (2}{1 + (1}$$

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ISRO Scientist or Engineer Electronics 2014 - Question 24

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Which of the following modulation scheme is most bandwidth efficient?

A

AM

B

FM

C

PM

D

SSB-SC

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ISRO Scientist or Engineer Electronics 2014 - Question 25

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A Colpitts Oscillator is having tank capacitances of InF and 10nF, and inductance of 0.1 $$\mu$$ H. The gain required by the circuit to start oscillating is :

A

10

B

100

C

1

D

1000

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 26

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A digital CMOS IC operating at 10MHz clock frequency consumes 100mW power; the same IC operating at 15 MHz clock frequency consumes 140mW power. Whatis the static power consumption of the IC?

A

10 mW

B

15 mW

C

20 mW

D

40 mW

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ISRO Scientist or Engineer Electronics 2014 - Question 27

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An amplifier has a gain of 50 dB, and noise figure of 10dB. Assuming an ambient temperature of 300 K, what will be the total equivalent noise temperature at the input of the amplifier?

A

760 K

B

360 K

C

2700 K

D

3000 K

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ISRO Scientist or Engineer Electronics 2014 - Question 28

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Diodes in the following circuit are ideal. Which is the correct waveform across $$R_L$$?

A

B

C

D

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ISRO Scientist or Engineer Electronics 2014 - Question 29

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Identify the modulation schemes for the shown signal constellation diagrams

A

(a)-QPSK (b)-BPSK (c)-QAM

B

(a)-QPSK (b)-OQPSK (c)-MSK

C

(a)-OQPSK (b)-QAM (c)-QPSK

D

(a)-OQPSK (b)-QPSK (c)-MSK

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 30

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The Fourier Transform of a discrete and aperiodic signal is:

A

Continuous and aperiodic

B

Continuous and periodic

C

Discrete and aperiodic

D

Discrete and periodic

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ISRO Scientist or Engineer Electronics 2014 - Question 31

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In the following circuit, Y can be expressed as:

A

$$Y = BC + A$$

B

$$Y = C$$

C

$$Y = AC + BC$$

D

$$Y = B$$

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ISRO Scientist or Engineer Electronics 2014 - Question 32

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$$s^2 - 0.75s + 0.25$$ is the characteristic equation of a second order system. Its response to unit step function will be,

A

Over damped

B

Under damped

C

Critically damped

D

Exponential growth

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 33

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Which modulation scheme would you suggest for high speed data transmission over a fading channel?

A

MSK

B

BPSK

C

FSK

D

OFDM

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ISRO Scientist or Engineer Electronics 2014 - Question 34

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For a two port network to be reciprocal, its Scattering parameters must satisfy the following condition, for i = 1, 2 ; j = 1, 2

A

$$S_{ij} = S_{ji} (i \neq j)$$

B

$$S_{ij} = S_{ji} (i = j)$$

C

$$S_{ij} = \frac{1}{S_{ji}} (i \neq j)$$

D

$$S_{ij} = S_{ji}^* (i = j)$$

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ISRO Scientist or Engineer Electronics 2014 - Question 35

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In the following circuit, what sequence is followed by A and B on rising edge of CLK after reset is de-asserted?

A

AB = 10, 11, 00, 10, 11, ...

B

AB = 10, 01, 00, 11, 10, ...

C

AB = 10, 00, 01, 10, 00, ...

D

AB = 11, 01, 00, 10, 11, ...

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 36

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In an axial mode operation of a helical antenna, maximum field radiated by the antenna is:

A

along the axis of the helical antenna

B

in a plane normal to the helix axis

C

in both axial and normal planes

D

None of the above

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ISRO Scientist or Engineer Electronics 2014 - Question 37

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Which of the following theorem is applicable for both linear and non-linear circuits?

A

Superposition theorem

B

Thevenin’s theorem

C

Norton’s theorem

D

None of these

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ISRO Scientist or Engineer Electronics 2014 - Question 38

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What is the maximum data rate that can be transmitted using a QPSK modulation with a roll-off factor of 0.2 for a 36 MHz transponder?

A

7.2 Mbps

B

30 Mbps

C

43.2 Mbps

D

60 Mbps

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 39

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Consider a single stage tuned amplifier having 3dB bandwidth of 100KHz. Determine the bandwidth if two such single stage tuned amplifiers are cascaded:

A

100 KHz

B

10 KHz

C

41.4 KHz

D

64.3 KHz

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ISRO Scientist or Engineer Electronics 2014 - Question 40

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500 Bytes of data needs to be transmitted from an UART every 100ms. What should be the minimum transmission baud rate of UART, assuming1 start bit, 8 data bits and 2 stop bits?

A

50000

B

55000

C

40000

D

45000

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 41

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What is the value of the major cross-sectional dimension(width) of a rectangular waveguide with dominant TE19 mode propagation, if its cut off frequency is 10 GHz?

A

15 mm

B

30 mm

C

7.5 mm

D

45 mm

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 42

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In a Traveling-wave Tube, the velocity of electron beam with respect to the axial velocity of RFfield is kept...

A

Lower

B

Higher

C

Equal

D

Any of these

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 43

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In satellite communication, scrambling is mainly used for -

A

clock recovery

B

encryption

C

limiting power spectral density

D

bandwidth efficiency

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ISRO Scientist or Engineer Electronics 2014 - Question 44

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Scattering Matrix for a microwave network, which is matchedatall the ports, will satisfy the following condition:

A

All non-diagonal elements will be zero.

B

All diagonal elements will be zero.

C

None of the matrix elements will be zero

D

All the matrix elements will be zero.

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ISRO Scientist or Engineer Electronics 2014 - Question 45

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Following waveform shows output of a 4 bit DAC with 5V reference voltage. The 4 bit digital input of DAC is connected to 4 bit up counter, the one bit input of DAC Is stuck at ‘0’, which is this bit ?

A

Bit-0 (LSB)

B

Bit-1

C

Bit-2

D

Bit-3 (MSB)

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 46

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Which of the followinghasthe highest skin depth?

A

Aluminum

B

Gold

C

Silver

D

Copper

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 47

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A network contains linear resistors and ideal voltage sources. If values of all the resistors are doubled,then voltage across each resistor is

A

Halved

B

Doubled

C

Increases by 4 times

D

Remains the same

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 48

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A coherent QPSK demodulatoris required on ground for receiving data from a LEO satellite. What should be optimum order of PLL in the carrier phase tracking loop?

A

$$1^{st}$$ order

B

$$2^{nd}$$ order

C

$$3^{rd}$$ order

D

None of the above

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 49

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VSWR of purely resistive load of normalized value n + j0 for n < 1 is :

A

n

B

1/n

C

1

D

Infinite

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ISRO Scientist or Engineer Electronics 2014 - Question 50

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Two discrete time systems have impulse response $$h_1[n] = \delta[n - 3]$$ and $$h_2[n] = \delta[n - 5]$$. If these two systems are cascaded, thenthe overall impulse response of the cascaded system is

A

$$\delta[n - 8]$$

B

$$\delta[n - 3] + \delta[n - 5]$$

C

$$\delta[n - 1] * \delta[n - 2]$$

D

$$\delta[n - 2]$$

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 51

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Frequency range of Ka-band EM waves is

A

18.0 GHz - 26.5 GHz

B

26.5 GHz - 40.0 GHz

C

12.0 GHz - 18.0 GHz

D

40.0 GHz - 60.0 GHz

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 52

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Following four resistances are connectedin parallel; the largest power is dissipated by ....
1) 2.4 Ω, 1W
2) 5.1 Ω, 2W
3) 10 Ω, 5W
4) 22 Ω, 10W

A

2.4 Ω, 1 W

B

5.1 Ω, 2 W

C

10 Ω, 5 W

D

22 Ω, 10 W

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 53

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Eye diagram gives us an idea of -

A

Modulation scheme

B

Clock jitter

C

Signal-to-Noise Ratio

D

All of the above

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ISRO Scientist or Engineer Electronics 2014 - Question 54

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Determine the correlation coefficient between the pulses x(t) and y(t) shown in the fig. below :

A

1

B

-1

C

0

D

$$2 \pi$$

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 55

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What is 4 point Discrete Fourier Transform of signal x(n) = (1, 2, 3, 4)

A

[10, 2j, -2, -2j]

B

[10,-2, -2, -2]

C

[10, -2 + 2j, -2, -2-2j]

D

[10j, -2, -2, -10j]

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 56

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The valueof axialratio of a $$45^\circ$$ linearly polarized EM wavein dB is

A

Infinite

B

0

C

1

D

2

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 57

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If an input signal with non-zero dc component is applied to a low pass RC network with single resistor R and single capacitor C as shown below, the dc component in the output will be :

A

The same as the input

B

Less than the input

C

More than the input

D

Zero

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 58

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The thermal noise spectral density generated in a resistor kept at $$t^\circ C$$ is given by:

A

k(t + 273)

B

ktB

C

k(t + 273)B

D

2k(t + 273)

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 59

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What are poles and zeros of a system having following transfer function?
$$H(z) = (1 - z^{-2})(1 + 1.3 z^{-1} + 0.36 z^{-2})$$

A

Zeros = -1, 1; Poles = -0.4, -0.9

B

Zeros = -1, 1; Poles = 0.4, 0.9

C

Zeros = 1; Poles = 0.4, -0.9

D

Zeros = 1, 1; Poles = 0.4, 0.9

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 60

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The change in phase of an electromagnetic wave normally incident on a perfect conducting wall is?

A

$$90^\circ$$

B

$$180^\circ$$

C

$$0^\circ$$

D

$$270^\circ$$

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ISRO Scientist or Engineer Electronics 2014 - Question 61

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What is the turns ratio of the transformer needed to match a 1 kΩ source resistance to a 50 Ω load?

A

4.47 : 1

B

400 : 1

C

20 : 1

D

0.05 : 1

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 62

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A satellite communication link has both uplink and downlink $$\frac{C}{N_o}$$, of 50dB-Hz. What would be overall link $$\frac{C}{N_o}$$?

A

25 dB-Hz

B

47 dB-Hz

C

53 dB-Hz

D

100 dB-Hz

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 63

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Determine polarization loss factor for a circularly polarized signal upon reception by linearly polarized antenna

A

$$\frac{1}{\sqrt{2}}$$

B

$$\frac{1}{2}$$

C

$$1$$

D

0

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 64

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Which instruction of 8051 microcontroller is used for reading data from code memory?

A

MOV

B

MOVC

C

MOVX

D

XCH

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 65

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If frequency is decreased 4 times, then skin depth of an Electromagnetic wave inside a conductor will be :

A

halved

B

quadrupled

C

doubled

D

no change

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ISRO Scientist or Engineer Electronics 2014 - Question 66

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In the circuit shown below, the current through 10 Ω resistor is :

A

5 A

B

10 A

C

-5 A

D

None of these

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ISRO Scientist or Engineer Electronics 2014 - Question 67

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If two tones $$f_1$$ and $$f_2$$ are amplified by a non-linear amplifier, which frequency components would be present in output?

A

$$f_1, f_2$$

B

$$f_1, f_2, f_1 + f_2, f_1 - f_2$$

C

$$f_1 + f_2, f_1 - f_2$$

D

$$nf_1 \pm mf_2$$, where n and m are integers

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ISRO Scientist or Engineer Electronics 2014 - Question 68

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When a sinusoidal voltage wave drives a Schmitt Trigger, the output is a:

A

Triangular wave

B

Rectified sine wave

C

Rectangular wave

D

Trapezoidal wave

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ISRO Scientist or Engineer Electronics 2014 - Question 69

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What will be content of Stack Pointer if following assembly code of 8051 microcontroller is executed immediately after reset?
PUSH 00h
POP OIh
POP 02h

A

07 h

B

06 h

C

0 Ah

D

31 h

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 70

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Consider the sampling of the band-pass signal, whose spectrum is as shown below. What minimum sampling frequency would you use from the options given below, so as to avoid aliasing?

A

24 Hz

B

26.5 Hz

C

48 Hz

D

212 Hz

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 71

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A resistor and a capacitor are connected in series with a sine wave generator having frequency suchthat the resistance and the capacitive reactance are same i.e. voltage across capacitance, $$V_c$$ is equal to Voltage across Resistance, $$V_R$$. If the frequency ofthe sine wave generator is doubled, then

A

$$V_R < V_C$$

B

$$V_R = V_C$$

C

$$V_R > V_C$$

D

None of the above

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 72

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In CMOS designs, why size of PMOS is kept larger than size of NMOS?

A

To get higher drive strength

B

To reduce power dissipation

C

To get balanced rise/fall time

D

All of above

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ISRO Scientist or Engineer Electronics 2014 - Question 73

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A plane wave with a frequency of 3 GHz is propagating in an unbounded medium with relative permittivity $$ε_r = 6$$ and permeability $$\mu_r = 1.5$$, the phase velocity for this wave in this medium is

A

$$1 \times 10^8$$ m/s

B

$$2 \times 10^8$$ m/s

C

$$3 \times 10^8$$ m/s

D

$$1.5 \times 10^8$$ m/s

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ISRO Scientist or Engineer Electronics 2014 - Question 74

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Which of the following statements is NOT true:

A

A high PRF pulse Doppler radar has no ambiguities in Doppler frequency.

B

A high PRF pulse Doppler radar has no range ambiguities.

C

Ahigh PRF pulse Doppler radar provides an accurate measurement of target’s radial velocity.

D

An MTI radar has many Doppler ambiguities.

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ISRO Scientist or Engineer Electronics 2014 - Question 75

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The Boolean equation for Y in the following circuit is

A

Y = (A(B + C) + D)’

B

Y = A(B + C) + D

C

Y = (A + BC)D

D

Y = ((A + BC)D)’

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ISRO Scientist or Engineer Electronics 2014 - Question 76

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A wave is incident from free-space onto a dielectric region of dielectric constant $$ε_r = 4$$. The wave impedance in the dielectricis :

A

55.5 Ω

B

100.5 Ω

C

108.6 Ω

D

188.5 Ω

View Solution

ISRO Scientist or Engineer Electronics 2014 - Question 77

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Range resolution of a Linear Frequency Modulated pulse compression radar depends on whichof the following factors:

A

Radiated power

B

Antenna size

C

Center frequency of the radar

D

Bandwidth of the transmitted pulse

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ISRO Scientist or Engineer Electronics 2014 - Question 78

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Which logical function is implemented by following Transmission Gate based circuit?

A

Y = XNOR(A,B)

B

Y = OR(A,B)

C

Y = AND(A,B)

D

Y = XOR(A,B)

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ISRO Scientist or Engineer Electronics 2014 - Question 79

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The orbital period of a satellite in circular orbit of radius R from the centre of the earth, is proportional to:

A

$$R^{\frac{1}{2}}$$

B

$$R^{\frac{3}{2}}$$

C

$$R^2$$

D

$$R$$

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ISRO Scientist or Engineer Electronics 2014 - Question 80

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Which of the following meters is based on the principle of Hall Effect?

A

Ammeter

B

Gaussmeter

C

Voltmeter

D

All of the above

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