Exam Details
Subject | electronics and communication engineering | |
Paper | ||
Exam / Course | ||
Department | ||
Organization | indian space research organisation | |
Position | ||
Exam Date | 2006 | |
City, State | , |
Question Paper
1. The value of-C which gives the critical damping in the given circuit is
<img src='./qimages/1642-1.jpg'>
2F
4F
8F
1F
2. A series RLC circuit resonates at 3 MHz and has 3-dB bandwidth kHz. The Q of the circuit at resonance
30
300/root2
300
300 root2
3. The value of resistance R shown in the given figure is
<img src='./qimages/1642-3.jpg'>
3.5 ohm
2.5 ohm
1 ohm
4.5 ohm
4. At 3-dB frequencies, current in the series RLC circuit equal current at resonance multiplied by
1/2
1/root2
1/4
1/2 root 2
5. A series RLC circuit resonates at 1000kHz. At frequency of 995kHz, the circuit impedance is
Resistive
minimum
Inductive
capacitive
6. If each stage had gain of 10dB and noise figure of 10dB, then the overall noise figure of two-stage cascade amplifier will be
10
1.09
1.0
10.9
7. In Sigma delta ADC, high bit accuracy is achieved by
Over sampling and noise shaping
Over sampling
Under sampling
None of the above
8. Let denote the delta function. The value of the integral <img src='./qimages/1642-8.jpg'> is
1
0
pie/2
9. Consider the compound system shown in the above figure.its-output is equal to the-input with a delay of two units. If the transfer function of the first system is given by Z-0.5/Z-0.8,then the <img src='./qimages/1642-9.jpg'>
<img src='./qimages/1642-9a.jpg'>
<img src='./qimages/1642-9a.jpg'>
<img src='./qimages/1642-9a.jpg'>
<img src='./qimages/1642-9a.jpg'>
10. The z-transform of the signal
<img src='./qimages/1642-10.jpg'>
<img src='./qimages/1642-10a.jpg'>
11. For the circuit shown in the given figure, the voltage VAB is
<img src='./qimages/1642-11.jpg'>
6V
10V
25V
40V
12. The equivalent capacitance across will be
<img src='./qimages/1642-12.jpg'>
0.2mewF
0.1mewF
0.5mewF
0
13. The transfer function, is that of a
Low-pass filter
Notch filter
High-pass filter
Band-pass filter
14. A particular current is made up of two components:a 10A dc and a sinusoidal current of peak value of 1.414 A. The average value of the resultant current is
Zero
24.14A
10A
14.14A
15. By doubling the sampling frequency
Quantisation noise decreases by 3dB
Quantisation noise density decreases by 3dB
Quantisation noise increases by 3dB
Quantisation noise density increases by 3dB
16. The output voltage of the circuit shown in the given figure is
<img src='./qimages/1642-16.jpg'>
Zero
5.7V
6.9V
12.6V
17. Assuming that only the X and Y logic inputs are available and their complements X and Y are not avaUable, what is the minimum number of two-input NAND gates requires to implement X
a)2
b)3
c)4
d)5
18. In the given network of AND and OR gates f can be written as: <img src='./qimages/1642-18.jpg'>
<img src='./qimages/1642-18a.jpg'>
19. A Pulse train with a frequency of 1MHz is counted using a modulo 1024 ripple-counter built with J-K flip-flops. For proper operation of the counter the maximum permissible propagation delay per flip-flop stage is
100 n sec
50 n sec
20 n sec
10 n sec
20. The A/D converter used in a digital voltmeter could be successive approximation type Flash converter type Dual slope converter type. The correct sequence in the increasing order of their conversion times is
21. The resolution of a D/A converter is approximately 0.4% of its-full-scale range. It is
An 8-bit converter
A 10-bit converter
A 12 bit converter
A 16 bit converter
22. In a microprocessor, the resister which holds the address of the next instruction to be fetched is
Accumulator
Program counter
Stack pointer
Instructor register
23. In microcomputer, WAIT states are used to
Make the processor wait during a DMA operation
Make the processor wait during a power interrupt processing
Make the processor wait during a power shutdown
Interface slow peripherals to the processor
24. Which of the following statements are correct 1)A flip-flop is used to store 1 bit of information 2)Race-around condition occurs in a J-K flip-flop when both the inputs are 1 3)Master-slave configuration is used in flip-flops to store 2 bits of information 4)A transparent latch consists of a D-type flip-flop
1,2and3
1,3and4
1,2and4
2,3and4
25. How many 1 are present in the binary representation of 3x512+7x64+5x8+3?
8
9
10
11
26. For emitter-coupled logic, the switching speed is very high because
Negative logic, is used
The transistors are not saturated when conducting
Emitter-coupled transistors are used
Multi-emitter transistors are used
27. The out put of the circuit shown below is <img src='./qimages/1642-27.jpg'>
A pulse train of duration 0.5 sec.
A pulse train of duration 2 sec.
A pulse train of duration 1 sec.
A pulse train of duration 5 sec.
28. Gray code for number 7 is
1100
1001
0110
0100
29. 10 bit AJD converters, the quantization error is given by (in percent)
1
2
0.1
02
30. For the switch-circuit,taking open as 0 and closed as the expression for the circuit is Y. <img src='./qimages/1642-30.jpg'>
A+BC+D
None of these
31. The Boolean expression for the shaded area in the Venn diagram is <img src='./qimages/1642-31.jpg'>
x bar+Y bar+Z
X Y bar Z bar YZ
XY barZ+XY
32. If the memory chip size is 256*1 bits, then the number of chips required to make up 1K bytes of memory is
32
24
12
8
33. Given the decimal number an eight bit two's complement representation is given by
11101110
11101101
11101100
None of these
34. The function shown in the figure when simplified will yield a result with <img src='./qimages/1642-34.jpg'>
2 terms
4 terms
7 terms
16 terms
35. The logic circuit given below converts a binary code Y1Y2Y3 into
Excess-3 code
Gray code
BCD code
Hamming code
36. A 4-bit synchronous counter uses flip-flops with propagation delay time of 25ns each. The maximum possible time required for change of state will be
a)25ns
b)50ns
c)75ns
d)100ns
37. An electromagnetic wave incident on a perfect conductor is
Entirely reflected
Fully transmitted
Partially transmitted
None of these
38. The characteristic impedance of a lossless transmission line is given by
Z=root LC
Z=root C/L
Z=LC
Z=root L/C
39. A lossless line of 50 ohms is terminated in a load of 100 ohms resistive. The VSWR is
1:2
2:1
4:1
1:4
40. Which of the following does not exist in wave guides
TE waves
TM waves
TE waves and TM waves
TEM waves
41. Two carriers of 2GHz and 4GHz respectively are frequency modulated by a signal of 10KHz,such that bandwidth of the FM signal in the two cases are same. The peak deviation in the two cases are in the ratio of
1:8
1:2
2:1
1:1
42. The bandwidth required for QPSK modulated channel is
Twice the BW of BPSK
Equal to BPSK
Equal to FSK
Half of the BW of BPSK
43. Magic T is
Four part junction
Two part junction
Three part junction
It is not junction
44. Diplexer is made of
Only receive filter
Only transmit filter
Only circulator filter
Both receive filter and transmit filter
45. The gain G of an antenna of effective area A is given by
G=4pie lamda/A2
G=4pieA/lamda
G=4pieA/lamda2
None
46. If the short circuit and open circuit impedance of a line are 5 and 20 ohm respectively the characteristic impedance is given by
100 ohm
10 ohm
15 ohm
10000 ohm
47. The input impedance of short circuited line of length l where lamda/4 l lamda/2, is
Capacitive
Inductive
Resistive
None of these
48. Maximum coding gain in
Block Codes
Convolution Codes
Turbo Codes
RS Codes
49. Noise figure of an amplifier depends on
Bandwidth
Output power
Power input
None of the above
50. BCH code belongs to
Block Codes
Convolution Codes
Turbo Codes
None of the above
51. When a carrier is phase modulated, with an integrated modulating signal, the resultant is
Phase modulated signal
Frequency modulated signal
Amplitude modulated signal
QPSK modulated signal
52. A satellite orbiting in 600km orbit transmits 5GHz frequency. The Doppler shift observed at the ground station, when the satellite. is over head of the station is
Zero
Maximum
Infinity above
None of the
53. A communication channel disturbed by additive white Gaussian noise has a bandwidth of 4kHz and SNR of 15. The highest transmission rate that such a channel can support (in k-bits/sec) is
16
1.6
3.2
60
54. A dual directional coupler connected in a microwave reflectometer measurement setup.The reading of the power meter in the forward direction is 100mw and in the reverse direction 4 mw. The VSWR is
4
0.4
1.5
10
55. Linear amplifier with a gain of 30dB is fed with 1.0mewW power, the output power of the amplifier
1.0W
0 dBm
30dBm
-30dBm
56. 10Watts RF power is transmitted with a circular polarized antenna having gain of 10dB. A receiving antenna has vertical polarization. The path loss is 100dB. The receiving signal is
-83dBW
-80dBW
-86dBW
+80dBW
57. P bar Q bar and R bar are in equilibrium,if R bar is
2k
i +2k
i j +2k
i -2k
58. A rigid body is rotating with constant angular velocity w about a fixed axis, if v is the velocity of a point of the body, then curl v
w
w2
2w
2w2
59. laplace transform of sin3 2t is
<img src='./qimages/1642-59a.jpg'>
<img src='./qimages/1642-59b.jpg'>
<img src='./qimages/1642-59c.jpg'>
<img src='./qimages/1642-59d.jpg'>
60. The value of the determinant <img src='./qimages/1642-60.jpg'> is
0
1
2
61. Solution of (D2 4)y sin2 is
<img src='./qimages/1642-61a.jpg'>
<img src='./qimages/1642-61b.jpg'>
<img src='./qimages/1642-61c.jpg'>
<img src='./qimages/1642-61d.jpg'>
62. The value of k for which the lines 2x 3y and 3x ky are concurrent is
3
2
63. A box cOl1tClin$ 5 black and 5 red balls. Two balls are randomly picked one after another from the box, without replacement. The probability for both balls being red is
1/90
1/5
19/90
2/9
64. x3+xsinx is
Constant function
Odd function
Even function
Periodic function
65. <img src='./qimages/1642-65.jpg'>
<img src='./qimages/1642-65a.jpg'>
<img src='./qimages/1642-65b.jpg'>
<img src='./qimages/1642-65c.jpg'>
<img src='./qimages/1642-65d.jpg'>
66. Eigen values of <img src='./qimages/1642-66.jpg'>
6,1
67. The approximate equivalent resistance at the points X1 and X2 in the circuit shown below
<img src='./qimages/1642-67.jpg'>
60 ohm
40 ohm
80 ohm
20 ohm
68. An inductor supplied with 50V ac with a frequency of 10kHz passes a current of 7.96 mA. The value of inductor is
1mH
10mH
100mH
1H
69. In a capacitor, the electric charge is stored in
Dielectric
Metal plates
Dielectric as well as metal plates
Neither dielectric nor metal plates
70. Oscillator requires
No feedback
Negative feedback
Positive feedback
Either positive or negative feedback
71. Which loss in a transformer varies significantly with load?
Hysteresis loss
Eddy current loss
Copper loss
Core loss
72. The resistance of a parallel circuit consisting of two resistors is 12 ohm. One of the resistance wires breaks and the effective resistance becomes 18 ohm. The resistance of the broken wire is
48 ohm
18 ohm
36 ohm
24 ohm
73. Time constant of a series R-L circuit equals
L/R second
LR second
L2 R
Zero
74. A dc voltage V is applied at time t=0 to a series RC circuit The steady state current is
V/R
V/C
V/root R2+C2
Zero
75. The given circuit represents a <img src='./qimages/1642-75.jpg'>
Low pass filter
High pass filter
Band pass
Band stop filter filter
76. The very low frequency gain of the low pass filter shown in the given figure is <img src='./qimages/1642-76.jpg'>
10dB
20dB
30dB
40dB
77. The time-constant of the network shown in the figure is
<img src='./qimages/1642-77.jpg'>
CR
2CR
CR/4
CR/2
78. For the circuit shown below the current I flowing through the circuit will be
<img src='./qimages/1642-78.jpg'>
1/2A
1A
2A
4A
79. When L is doubled and C is halved, the resonance frequency of series tuned circuit becomes
Doubled
Halved
One quarter
Unchanged
80. In a Series resonant circuit, with the increase in L
Resonant frequency will decrease
Bandwidth will decrease
Q will increase
All of these
<img src='./qimages/1642-1.jpg'>
2F
4F
8F
1F
2. A series RLC circuit resonates at 3 MHz and has 3-dB bandwidth kHz. The Q of the circuit at resonance
30
300/root2
300
300 root2
3. The value of resistance R shown in the given figure is
<img src='./qimages/1642-3.jpg'>
3.5 ohm
2.5 ohm
1 ohm
4.5 ohm
4. At 3-dB frequencies, current in the series RLC circuit equal current at resonance multiplied by
1/2
1/root2
1/4
1/2 root 2
5. A series RLC circuit resonates at 1000kHz. At frequency of 995kHz, the circuit impedance is
Resistive
minimum
Inductive
capacitive
6. If each stage had gain of 10dB and noise figure of 10dB, then the overall noise figure of two-stage cascade amplifier will be
10
1.09
1.0
10.9
7. In Sigma delta ADC, high bit accuracy is achieved by
Over sampling and noise shaping
Over sampling
Under sampling
None of the above
8. Let denote the delta function. The value of the integral <img src='./qimages/1642-8.jpg'> is
1
0
pie/2
9. Consider the compound system shown in the above figure.its-output is equal to the-input with a delay of two units. If the transfer function of the first system is given by Z-0.5/Z-0.8,then the <img src='./qimages/1642-9.jpg'>
<img src='./qimages/1642-9a.jpg'>
<img src='./qimages/1642-9a.jpg'>
<img src='./qimages/1642-9a.jpg'>
<img src='./qimages/1642-9a.jpg'>
10. The z-transform of the signal
<img src='./qimages/1642-10.jpg'>
<img src='./qimages/1642-10a.jpg'>
11. For the circuit shown in the given figure, the voltage VAB is
<img src='./qimages/1642-11.jpg'>
6V
10V
25V
40V
12. The equivalent capacitance across will be
<img src='./qimages/1642-12.jpg'>
0.2mewF
0.1mewF
0.5mewF
0
13. The transfer function, is that of a
Low-pass filter
Notch filter
High-pass filter
Band-pass filter
14. A particular current is made up of two components:a 10A dc and a sinusoidal current of peak value of 1.414 A. The average value of the resultant current is
Zero
24.14A
10A
14.14A
15. By doubling the sampling frequency
Quantisation noise decreases by 3dB
Quantisation noise density decreases by 3dB
Quantisation noise increases by 3dB
Quantisation noise density increases by 3dB
16. The output voltage of the circuit shown in the given figure is
<img src='./qimages/1642-16.jpg'>
Zero
5.7V
6.9V
12.6V
17. Assuming that only the X and Y logic inputs are available and their complements X and Y are not avaUable, what is the minimum number of two-input NAND gates requires to implement X
a)2
b)3
c)4
d)5
18. In the given network of AND and OR gates f can be written as: <img src='./qimages/1642-18.jpg'>
<img src='./qimages/1642-18a.jpg'>
19. A Pulse train with a frequency of 1MHz is counted using a modulo 1024 ripple-counter built with J-K flip-flops. For proper operation of the counter the maximum permissible propagation delay per flip-flop stage is
100 n sec
50 n sec
20 n sec
10 n sec
20. The A/D converter used in a digital voltmeter could be successive approximation type Flash converter type Dual slope converter type. The correct sequence in the increasing order of their conversion times is
21. The resolution of a D/A converter is approximately 0.4% of its-full-scale range. It is
An 8-bit converter
A 10-bit converter
A 12 bit converter
A 16 bit converter
22. In a microprocessor, the resister which holds the address of the next instruction to be fetched is
Accumulator
Program counter
Stack pointer
Instructor register
23. In microcomputer, WAIT states are used to
Make the processor wait during a DMA operation
Make the processor wait during a power interrupt processing
Make the processor wait during a power shutdown
Interface slow peripherals to the processor
24. Which of the following statements are correct 1)A flip-flop is used to store 1 bit of information 2)Race-around condition occurs in a J-K flip-flop when both the inputs are 1 3)Master-slave configuration is used in flip-flops to store 2 bits of information 4)A transparent latch consists of a D-type flip-flop
1,2and3
1,3and4
1,2and4
2,3and4
25. How many 1 are present in the binary representation of 3x512+7x64+5x8+3?
8
9
10
11
26. For emitter-coupled logic, the switching speed is very high because
Negative logic, is used
The transistors are not saturated when conducting
Emitter-coupled transistors are used
Multi-emitter transistors are used
27. The out put of the circuit shown below is <img src='./qimages/1642-27.jpg'>
A pulse train of duration 0.5 sec.
A pulse train of duration 2 sec.
A pulse train of duration 1 sec.
A pulse train of duration 5 sec.
28. Gray code for number 7 is
1100
1001
0110
0100
29. 10 bit AJD converters, the quantization error is given by (in percent)
1
2
0.1
02
30. For the switch-circuit,taking open as 0 and closed as the expression for the circuit is Y. <img src='./qimages/1642-30.jpg'>
A+BC+D
None of these
31. The Boolean expression for the shaded area in the Venn diagram is <img src='./qimages/1642-31.jpg'>
x bar+Y bar+Z
X Y bar Z bar YZ
XY barZ+XY
32. If the memory chip size is 256*1 bits, then the number of chips required to make up 1K bytes of memory is
32
24
12
8
33. Given the decimal number an eight bit two's complement representation is given by
11101110
11101101
11101100
None of these
34. The function shown in the figure when simplified will yield a result with <img src='./qimages/1642-34.jpg'>
2 terms
4 terms
7 terms
16 terms
35. The logic circuit given below converts a binary code Y1Y2Y3 into
Excess-3 code
Gray code
BCD code
Hamming code
36. A 4-bit synchronous counter uses flip-flops with propagation delay time of 25ns each. The maximum possible time required for change of state will be
a)25ns
b)50ns
c)75ns
d)100ns
37. An electromagnetic wave incident on a perfect conductor is
Entirely reflected
Fully transmitted
Partially transmitted
None of these
38. The characteristic impedance of a lossless transmission line is given by
Z=root LC
Z=root C/L
Z=LC
Z=root L/C
39. A lossless line of 50 ohms is terminated in a load of 100 ohms resistive. The VSWR is
1:2
2:1
4:1
1:4
40. Which of the following does not exist in wave guides
TE waves
TM waves
TE waves and TM waves
TEM waves
41. Two carriers of 2GHz and 4GHz respectively are frequency modulated by a signal of 10KHz,such that bandwidth of the FM signal in the two cases are same. The peak deviation in the two cases are in the ratio of
1:8
1:2
2:1
1:1
42. The bandwidth required for QPSK modulated channel is
Twice the BW of BPSK
Equal to BPSK
Equal to FSK
Half of the BW of BPSK
43. Magic T is
Four part junction
Two part junction
Three part junction
It is not junction
44. Diplexer is made of
Only receive filter
Only transmit filter
Only circulator filter
Both receive filter and transmit filter
45. The gain G of an antenna of effective area A is given by
G=4pie lamda/A2
G=4pieA/lamda
G=4pieA/lamda2
None
46. If the short circuit and open circuit impedance of a line are 5 and 20 ohm respectively the characteristic impedance is given by
100 ohm
10 ohm
15 ohm
10000 ohm
47. The input impedance of short circuited line of length l where lamda/4 l lamda/2, is
Capacitive
Inductive
Resistive
None of these
48. Maximum coding gain in
Block Codes
Convolution Codes
Turbo Codes
RS Codes
49. Noise figure of an amplifier depends on
Bandwidth
Output power
Power input
None of the above
50. BCH code belongs to
Block Codes
Convolution Codes
Turbo Codes
None of the above
51. When a carrier is phase modulated, with an integrated modulating signal, the resultant is
Phase modulated signal
Frequency modulated signal
Amplitude modulated signal
QPSK modulated signal
52. A satellite orbiting in 600km orbit transmits 5GHz frequency. The Doppler shift observed at the ground station, when the satellite. is over head of the station is
Zero
Maximum
Infinity above
None of the
53. A communication channel disturbed by additive white Gaussian noise has a bandwidth of 4kHz and SNR of 15. The highest transmission rate that such a channel can support (in k-bits/sec) is
16
1.6
3.2
60
54. A dual directional coupler connected in a microwave reflectometer measurement setup.The reading of the power meter in the forward direction is 100mw and in the reverse direction 4 mw. The VSWR is
4
0.4
1.5
10
55. Linear amplifier with a gain of 30dB is fed with 1.0mewW power, the output power of the amplifier
1.0W
0 dBm
30dBm
-30dBm
56. 10Watts RF power is transmitted with a circular polarized antenna having gain of 10dB. A receiving antenna has vertical polarization. The path loss is 100dB. The receiving signal is
-83dBW
-80dBW
-86dBW
+80dBW
57. P bar Q bar and R bar are in equilibrium,if R bar is
2k
i +2k
i j +2k
i -2k
58. A rigid body is rotating with constant angular velocity w about a fixed axis, if v is the velocity of a point of the body, then curl v
w
w2
2w
2w2
59. laplace transform of sin3 2t is
<img src='./qimages/1642-59a.jpg'>
<img src='./qimages/1642-59b.jpg'>
<img src='./qimages/1642-59c.jpg'>
<img src='./qimages/1642-59d.jpg'>
60. The value of the determinant <img src='./qimages/1642-60.jpg'> is
0
1
2
61. Solution of (D2 4)y sin2 is
<img src='./qimages/1642-61a.jpg'>
<img src='./qimages/1642-61b.jpg'>
<img src='./qimages/1642-61c.jpg'>
<img src='./qimages/1642-61d.jpg'>
62. The value of k for which the lines 2x 3y and 3x ky are concurrent is
3
2
63. A box cOl1tClin$ 5 black and 5 red balls. Two balls are randomly picked one after another from the box, without replacement. The probability for both balls being red is
1/90
1/5
19/90
2/9
64. x3+xsinx is
Constant function
Odd function
Even function
Periodic function
65. <img src='./qimages/1642-65.jpg'>
<img src='./qimages/1642-65a.jpg'>
<img src='./qimages/1642-65b.jpg'>
<img src='./qimages/1642-65c.jpg'>
<img src='./qimages/1642-65d.jpg'>
66. Eigen values of <img src='./qimages/1642-66.jpg'>
6,1
67. The approximate equivalent resistance at the points X1 and X2 in the circuit shown below
<img src='./qimages/1642-67.jpg'>
60 ohm
40 ohm
80 ohm
20 ohm
68. An inductor supplied with 50V ac with a frequency of 10kHz passes a current of 7.96 mA. The value of inductor is
1mH
10mH
100mH
1H
69. In a capacitor, the electric charge is stored in
Dielectric
Metal plates
Dielectric as well as metal plates
Neither dielectric nor metal plates
70. Oscillator requires
No feedback
Negative feedback
Positive feedback
Either positive or negative feedback
71. Which loss in a transformer varies significantly with load?
Hysteresis loss
Eddy current loss
Copper loss
Core loss
72. The resistance of a parallel circuit consisting of two resistors is 12 ohm. One of the resistance wires breaks and the effective resistance becomes 18 ohm. The resistance of the broken wire is
48 ohm
18 ohm
36 ohm
24 ohm
73. Time constant of a series R-L circuit equals
L/R second
LR second
L2 R
Zero
74. A dc voltage V is applied at time t=0 to a series RC circuit The steady state current is
V/R
V/C
V/root R2+C2
Zero
75. The given circuit represents a <img src='./qimages/1642-75.jpg'>
Low pass filter
High pass filter
Band pass
Band stop filter filter
76. The very low frequency gain of the low pass filter shown in the given figure is <img src='./qimages/1642-76.jpg'>
10dB
20dB
30dB
40dB
77. The time-constant of the network shown in the figure is
<img src='./qimages/1642-77.jpg'>
CR
2CR
CR/4
CR/2
78. For the circuit shown below the current I flowing through the circuit will be
<img src='./qimages/1642-78.jpg'>
1/2A
1A
2A
4A
79. When L is doubled and C is halved, the resonance frequency of series tuned circuit becomes
Doubled
Halved
One quarter
Unchanged
80. In a Series resonant circuit, with the increase in L
Resonant frequency will decrease
Bandwidth will decrease
Q will increase
All of these