do not open this booklet until you are asked … · this question paper contains total of 60...

1

GUJARAT FIBRE GRID NETWORK LIMITED (GFGNL)

DO NOT OPEN THIS BOOKLET UNTIL YOU ARE ASKED TO DO SO

Number Series

001 QUESTION PAPER JUNIOR TECHNICAL ENGINEER A

Time: 60 Minutes Maximum Marks: 60

General Instructions

1. This question paper contains total of 60 questions. Each question is of

multiple choice type.

2. For each question, you need to pick exactly one of the four choices which you think is the most appropriate answer for the question.

3. Each question carries one mark and you need to attempt all the questions.

4. Answers to the questions are to be marked on the OMR sheet provided.

Instructions for writing on OMR sheet

1. Fill in the question paper series code give above in your OMR sheet.

2. As far as possible, fill in the answer only after you are sure that you do not need to change it. Once an answer is filled in the OMR sheet, it cannot be changed/erased.

3. Check that you are filling the answer for the corresponding question on the

OMR sheet.

Richa Garg

Richa Garg

MasterCopy

2

Space for Rough Work

3

1. The signal cosω%t + 0.5cosω+tsinω%t is

A. FM B. Both AM and FM C. AM only D. Neither AM nor FM

Hint: narrow band FM or AM

2. In a digital communication system employing Frequency Shift

Keying, the 0 and 1 bit are represented by sine waves of 10 kHz and 25 kHz respectively. These waveforms will be orthogonal for a bit interval of

A. 45µsec B. 200 µsec C. 50 µsec D. 250 µsec

3. The frequency range for satellite communication is

A. 1 kHz to 100 kHz B. 10 MHz to 30 MHz C. 1 GHz to 30 GHz D. 100 kHz to 10 kHz

4. In commercial TV transmission in India, picture and image are

modulated using A. FM and VSB respectively B. FSK and AM respectively C. VSB and FM respectively D. AM and VSB respectively

5. Consider the amplitude modulated (AM) signal A%cosω%t +

2cosω+tcosω%t . For demodulating the signal using envelope detector, the minimum value of AC should be

A. 2 B. 1 C. 0 D. 0.5

6. Consider the signal s(t) = m(t)cos(2πf%t) + m7(t)sin(2πf%t)

where m7(t) denotes the Hilbert transform of m(t) and bandwidth of m(t) is very small compared to fc . The signal s(t) is a

A. Band pass signal B. High pass signal C. Low pass signal D. constant signal

4

7. Choose the correct answer: A message signal m(t) = A+sin(2πf+t) is used to modulate the phase of a carrier A%cos(2πf%t) to get the modulated signal y(t) = A%cos(2πf%t + m(t)). The bandwidth of y(t)

A. depends on Am but not on fm B. depends on both Am and fm C. depends on fm but not on Am D. Only on Am

8. The expression for bandwidth BW of a PCM system, where v is the

number of bits per sample and fm is the modulating frequency, is given by

A. BW ≥ vfm B. BW ≤ vfm C. BW ≥ 2vfm D. BW ≥ 0.5vfm

9. Photonic crystal fibers finds application in A. Dispersion compensation B. Switches C. Both of the above D. Neither (a) nor (b)

10. The fibers mostly not used nowadays for optical fiber

communication system are A. single mode fibers B. multimode step fibers C. coaxial cables D. multimode graded index fibers

11. The best time to sample a received waveform is

A. At the rise time of the eye diagram B. When the height of the eye opening is largest C. When the height of the eye opening is minimum D. At the zero crossing

12. Which of the following analog modulation scheme requires the

minimum transmitted power and minimum channel bandwidth? A. VSB B. DSB-SC C. SSB D. AM

13. The spatial resolution of an OTDR is determined by –

A. pulse power B. pulse width C. pulse repetition rate D. speed of light in the fiber

5

14. A 2 × 2 biconical tapered fiber coupler has an input optical power

level of 200 µW. The output powers at the other three ports are P1= 90 µW, P2= 85 µW, and P3=6.3 nW. The return losses and the coupling ratio are

A. -3.47 dB and 23.9% respectively B. -3.47 dB and 46.8% respectively C. -45 dB and 48.6% respectively D. -45 dB and 23.9% respectively

15. Which factor adds phase noise to the signal?

A. jitter B. phase fluctuations C. jitter & phase fluctuations D. None of the above

16. The probability of error of DPSK is ______________ that of BPSK.

A. higher than B. lower than C. same as D. Not predictable

17. At 1310 nm wavelength corresponds to

A. Minimum attenuation B. Minimum chromatic dispersion C. Minimum delay D. Both (a) and (b)

18. A step-index fiber has a core refractive index of 1.480, a core

radius of 4.5 µm, and a core-cladding index difference of 0.25 percent. What is the cutoff wavelength for this fiber? (V=2.405)

A. 1290 nm B. 1230 nm C. 1320 nm D. 1190 nm

19. The advantage of using Manchester format of coding is

A. Power saving B. Polarity sense at the receiver C. Noise immunity D. None of the above

20. The diagonal clipping in Amplitude Demodulation (using envelope

detector) can be avoided if RC time-constant of the envelope detector satisfies the following condition, (here W is message bandwidth and ω is carrier frequency both in rad/sec)

A. 9: < <=

6

B. 9: > <=

C. 9: > <?

D. 9: < <?

21. The typical loss of a communications-grade fiber is 0.1 dB/km. If 1

dBm of signal power is launched into the fiber, what percentage of power remains in the fiber after propagation of 10 km? A. 80% B. 90% C. 85% D. 95%

22. Laser diodes are preferred over light emitting diodes as optical

sources because – A. They have higher power B. They have smaller spectral width C. They are cheaper D. They can be fiber coupled

23. Which phenomenon causes the dynamic line width broadening

under the direct modulation of injection current? A. modal noise B. mode-partition noise C. frequency chirping D. reflection noise

24. The connector that has two fiber ends adjacent to each other an

angled at 8 degrees is – A. FC-PC B. FC-SC C. FC-APC D. None of the above

25. The main use of an optical time domain reflectometer is to _____.

A. measure loss in a fiber B. locate faults in a fiber-optic link C. measure the total length of a fiber cable D. None of the above

26. Which is the correct order of sequential steps for an electric arc

fusion technique?

7

I. Pressing of fiber ends for fusion II. Application of heat for smoothening of end-surfaces III. Alignment of broken fiber edges

A. I, II, III B. II, I, III C. III, II, I D. III, I, II

27. Fiber-to-the-Home technology has highest penetration in –

A. Japan B. United States of America C. South Korea D. United Kingdom

28. The advent of the ___________ has given trans-oceanic optical

fiber communications the biggest boost. A. high power laser diodes B. photonic crystal fiber C. erbium doped fiber amplifier D. neodymium-doped glass

29. The trademark SMF-28 refers to fiber with the following

characteristics – A. Core radius 125 micron; cladding radius 250 micron B. Core radius 9 micron; cladding radius 125 micron C. Core radius 12 micron; cladding radius 125 micron D. Core radius 28 micron; cladding radius 250 micron

30. The modulation format that is used for the highest capacity

transmission is A. phase shift keying B. on-off keying C. quadrature amplitude modulation D. frequency shift keying

31. The ratio of bandwidth to the resonant frequency is called ______

of the circuit A. Impedance B. Susceptance C. Selectivity D. Quality factor

32. In a series resonant circuit at resonance, the source voltage is

same as that of voltage across

8

A. inductor B. capacitor C. resistor D. none of the above

33. The difference between the half power frequencies is called

A. Bandwidth B. Cut of frequency C. Quality factor D. Resonant frequency

34. What kind of filter can be used to select a signal of one particular

radio station? A. Band pass B. Band stop C. Low pass D. High pass

35. A series RLC circuit consists of a resistance of 10W, an inductance

of 100mH and a capacitance of 10 mF. The Q factor of the circuit is A. 50 B. 10 C. 20 D. 100

36. Transient currents are associated with

A. Applied voltage to the circuit B. Resistance of the circuit C. Changes in the stored energy of the inductors and capacitors D. Impedance of the circuit

37. In a series RLC circuit setting R = 0 will produce

A. a critically damped response B. an overdamped response C. an underdamped response D. an undamped response

38. In a uniform electric field, the field lines and equipotentials

A. are parallel to one another B. intersect at 45 degree C. intersect at 30 degree D. are orthogonal

9

39. When the plate area of a parallel plate capacitor is increased keeping the capacitor voltage constant, the force between the plates

A. increases B. decreases C. remains constant D. may increase or decrease depending on the metal making up

the plates

40. A voltage waveform V(t) = 12 t2 is applied across a 1H inductor for t ≥ 0, with initial current through it being zero. The current through the inductor for t ≥ 0 is

A. 12 t B. 24 t C. 12 t3 D. 4 t3

41. The length of a wire of resistance R is uniformly stretched to n

times to its original value, its new resistance is A. nR B. R/n C. n2R D. R/n2

42. Varactor diodes are primarily used

A. In low frequency amplifiers B. As signal detectors C. To rectify power supplies D. In parametric amplifiers and harmonic generators at

microwave frequencies

43. A property of Semiconductors that is important in high frequency application is

A. High carrier mobility B. Wide energy gap C. High resistivity at room temperature D. Narrow energy gap

44. The high resistance of the reverse biased collector junction is due

to the fact that A. A small change in emitter current causes almost equal change

in collector current B. A small change in emitter bias voltage causes a large change

in collector current

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C. A large change in collector bias voltage causes a very little change in collector current

D. A small change in collector bias voltage causes a large change in collector current

45. When current feedback (negative) is applied to an amplifier, its

output impedance A. is increased B. is decreased C. remains same D. none of the above

46. Which of the following methods for a amplifier gives the highest

gain? A. Resistance coupling B. Impedance coupling C. Capacitance coupling D. Transformer coupling

47. The main factor which differentiates a Depletion MOSFET from an

Enhancement type MOSFET is A. Insulated Gate B. electrons C. Channel D. P-N junctions

48. OP AMP used as a tuned amplifier has the tuned circuit connected

A. across input B. Across the series impedance at the input C. across feedback impedance Zf D. across output

49. An OP AMP has slew rate of 5V/µs. The largest sinewave output

voltage possible at a frequency of 1MHz is A. 10π volts B. 5 volts C. 5/ π volts D. 5/2 π volts

50. The bipolar junction transistor (BJT) is used as a power control

switch by biasing it in the cut-off region (OFF state) or in the saturation region (ON state). In the ON state, for the BJT

A. Both the base-emitter and base-collector junctions are reverse biased

11

B. The base-emitter junction is reverse biased, and the base-collector junction is forward biased

C. The base-emitter junction is forward biased, and the base-collector junction is reverse biased

D. Both the base-emitter and base-collector junctions are forward biased

51. In which of the following gates, the output will be one, if and only

if one of the inputs is one? A. AND B. OR C. NAND D. NOR

52. Which of the following best defines the function of a multiplexer in

a digital system? A. To decode information. B. To transmit data on ‘N’ lines simultaneously. C. To perform serialization and deserialization functions. D. To select one out of ‘N’ sources and transmit that data to

output

53. What is the function of a latch in digital circuits? A. An asynchronous device to store state information B. An asynchronous device to transmit data C. A mechanism to detect falling edge of the clock D. None of the above

54. How many different numbers a 6-bit binary word can represent?

A. 63 B. 64 C. 127 D. 128

55. What is the decimal equivalent of the hexadecimal number

‘0xABCD’ A. 43981 B. 42671 C. 32572 D. 54331

12

56. 1110110, 1101100 and 100010 correspond to the 2’s complement representation of three numbers which are:

A. -10, -20, -30 B. -8, -12, -40 C. -20, -30, -40 D. none of above

57. The maximum memory size that can be accessed by a processor

having 16-bit data bus and 32-bit address bus is A. 4 Gigabytes B. 4 Gigawords C. 16 Megabytes D. 16 Megawords

58. The CMOS implementation of the function f= (ABC+DE)’ needs

_____ number of transistors. A. 5 B. 10 C. 12 D. 14

59. A ⊕ B ⊕ AB = ____________

A. A ⊕ B B. AB C. A + B D. none of these

60. The minimum number of 2:1 MUXes required for the design of a 2

input XOR gate is _______. A. 3 B. 2 C. 4 D. cannot be implemented

1



Number Series

001 QUESTION PAPER JUNIOR TECHNICAL ENGINEER B









1. Fill in the question paper series code given above in your OMR sheet.



OMR sheet.

Richa Garg

Richa Garg

MasterCopy

2


3

1. The ratio of bandwidth to the resonant frequency is called _______ of the circuit

A. Impedance B. Susceptance C. Selectivity D. Quality factor

2. In a series resonant circuit at resonance, the source voltage is same

as that of voltage across A. inductor B. capacitor C. resistor D. none of the above





5. A series RLC circuit consists of a resistance of 10W, an inductance of

100mH and a capacitance of 10 mF. The Q factor of the circuit is A. 50 B. 10 C. 20 D. 100




A. a critically damped response B. an overdamped response

4

C. an underdamped response D. an undamped response



9. When the plate area of a parallel plate capacitor is increased

keeping the capacitor voltage constant, the force between the plates


the plates


A. 12 t B. 24 t C. 12 t3 D. 4 t3







A. High carrier mobility B. Wide energy gap C. High resistivity at room temperature

5

D. Narrow energy gap

14. The high resistance of the reverse biased collector junction is due to the fact that

A. A small change in emitter current causes almost equal change in collector current

B. A small change in emitter bias voltage causes a large change in collector current












voltage possible at a frequency of 1MHz is A. 10π volts B. 5 volts C. 5/π volts

6

D. 5/2π volts

20. The bipolar junction transistor (BJT) is used as a power control switch by biasing it in the cut-off region (OFF state) or in the saturation region (ON state). In the ON state, for the BJT





21. The signal !"#$%& + 0.5!"#$+&#,-$%& is

A. FM B. Both AM and FM C. AM only D. Neither AM nor FM


22. In a digital communication system employing Frequency Shift

Keying, the 0 and 1 bit are represented by sine waves of 10 kHz and 25 kHz respectively. These waveforms will be orthogonal for a bit interval of

A. 45 µsec B. 200 µsec C. 50 µsec D. 250 µsec





25. Consider the amplitude modulated (AM) signal .%!"#$%& +

2!"#$+&!"#$%& . For demodulating the signal using envelope detector, the minimum value of AC should be

7

A. 2 B. 1 C. 0 D. 0.5

26. Consider the signal

#(&) = 3(&)!"#(256%&) + 37(&)#,-(256%&) where 37(t) denotes the Hilbert transform of m(t) and bandwidth of m(t) is very small compared to fc . The signal s(t) is a


27. Choose the correct answer: A message signal 3(&) = .+#,-(256+&)

is used to modulate the phase of a carrier .%!"#(256%&) to get the modulated signal 8(&) = .%!"#(256%& +3(&)). The bandwidth of y(t)





29. Photonic crystal fibers finds application in A. Dispersion compensation B. Switches C. Both of the above D. Neither (a) nor (b)




A. At the rise time of the eye diagram B. When the height of the eye opening is largest

8

C. When the height of the eye opening is minimum D. At the zero crossing






level of 200 µW. The output powers at the other three ports are P1= 90 µW, P2= 85 µW, and P3=6.3 nW. The return losses and the coupling ratio are










A. 1290 nm

9

B. 1230 nm C. 1320 nm D. 1190 nm





A. 9: < <=

B. 9: > <=

C. 9: > <?

D. 9: < <?


dBm of signal power is launched into the fiber, what percentage of power remains in the fiber after propagation of 10 km?

A. 80% B. 90% C. 85% D. 95%





10

44. The connector that has two fiber ends adjacent to each other an angled at 8 degrees is –

A. FC-PC B. FC-SC C. FC-APC D. None of the above




fusion technique? I. Pressing of fiber ends for fusion II. Application of heat for smoothening of end-surfaces III. Alignment of broken fiber edges







a digital system? A. To decode information. B. To transmit data on ‘N’ lines simultaneously. C. To perform serialization and deserialization functions.

11

D. To select one out of ‘N’ sources and transmit that data to output

50. What is the function of a latch in digital circuits?

A. An asynchronous device to store state information B. An asynchronous device to transmit data C. A mechanism to detect falling edge of the clock D. None of the above








A. 63 B. 64 C. 127 D. 128


‘0xABCD’ A. 43981 B. 42671 C. 32572 D. 54331

E.

12

56. 1110110, 1101100 and 100010 correspond to the 2’s complement representation of three numbers which are:

A. -10, -20, -30 B. -8, -12, -40 C. -20, -30, -40 D. none of above





59. A ⊕ B ⊕ AB = ____________




1



Number Series

001 QUESTION PAPER JUNIOR TECHNICAL ENGINEER C









1. Fill in the question paper series code given above in your OMR sheet.



OMR sheet.

Richa Garg

Richa Garg

MasterCopy

2


3

1. The ratio of bandwidth to the resonant frequency is called _______ of the circuit

A. Impedance B. Susceptance C. Selectivity D. Quality factor

2. In a series resonant circuit at resonance, the source voltage is same

as that of voltage across A. inductor B. capacitor C. resistor D. none of the above





5. A series RLC circuit consists of a resistance of 10W, an inductance of

100mH and a capacitance of 10 mF. The Q factor of the circuit is A. 50 B. 10 C. 20 D. 100




A. a critically damped response B. an overdamped response

4

C. an underdamped response D. an undamped response



9. When the plate area of a parallel plate capacitor is increased

keeping the capacitor voltage constant, the force between the plates


the plates


A. 12 t B. 24 t C. 12 t3 D. 4 t3







A. High carrier mobility B. Wide energy gap C. High resistivity at room temperature

5

D. Narrow energy gap

14. The high resistance of the reverse biased collector junction is due to the fact that

A. A small change in emitter current causes almost equal change in collector current

B. A small change in emitter bias voltage causes a large change in collector current












voltage possible at a frequency of 1MHz is A. 10π volts B. 5 volts C. 5/π volts

6

D. 5/2π volts

20. The bipolar junction transistor (BJT) is used as a power control switch by biasing it in the cut-off region (OFF state) or in the saturation region (ON state). In the ON state, for the BJT












A. 63 B. 64 C. 127 D. 128


‘0xABCD’ A. 43981

7

B. 42671 C. 32572 D. 54331

E. 26. 1110110, 1101100 and 100010 correspond to the 2’s

complement representation of three numbers which are: A. -10, -20, -30 B. -8, -12, -40 C. -20, -30, -40 D. none of above





29. A ⊕ B ⊕ AB = ____________




31. The signal "#$%&' + 0.5"#$%,'$-.%&' is

A. FM B. Both AM and FM C. AM only

8

D. Neither AM nor FM


32. In a digital communication system employing Frequency Shift Keying, the 0 and 1 bit are represented by sine waves of 10 kHz and 25 kHz respectively. These waveforms will be orthogonal for a bit interval of

A. 45 µsec B. 200 µsec C. 50 µsec D. 250 µsec





35. Consider the amplitude modulated (AM) signal /&"#$%&' +

2"#$%,'"#$%&' . For demodulating the signal using envelope detector, the minimum value of AC should be

A. 2 B. 1 C. 0 D. 0.5

36. Consider the signal

$(') = 4(')"#$(267&') + 48(')$-.(267&') where 48(t) denotes the Hilbert transform of m(t) and bandwidth of m(t) is very small compared to fc . The signal s(t) is a


37. Choose the correct answer: A message signal 4(') = /,$-.(267,')

is used to modulate the phase of a carrier /&"#$(267&') to get the modulated signal 9(') = /&"#$(267&' +4(')). The bandwidth of y(t)

9





39. Photonic crystal fibres finds application in A. Dispersion compensation B. Switches C. Both of the above D. Neither (a) nor (b)




A. At the rise time of the eye diagram B. When the height of the eye opening is largest C. When the height of the eye opening is minimum D. At the zero crossing






level of 200 µW. The output powers at the other three ports are P1=

10

90 µW, P2= 85 µW, and P3=6.3 nW. The return losses and the coupling ratio are










A. 1290 nm B. 1230 nm C. 1320 nm D. 1190 nm





A. :; < =>

B. :; > =>

C. :; > =@

11

D. :; < =@


dBm of signal power is launched into the fiber, what percentage of power remains in the fiber after propagation of 10 km?

A. 80% B. 90% C. 85% D. 95%





54. The connector that has two fiber ends adjacent to each other an

angled at 8 degrees is – A. FC-PC B. FC-SC C. FC-APC D. None of the above




fusion technique? I. Pressing of fiber ends for fusion II. Application of heat for smoothening of end-surfaces

12

III. Alignment of broken fiber edges







a digital system? A. To decode information. B. To transmit data on ‘N’ lines simultaneously. C. To perform serialization and deserialization functions. D. To select one out of ‘N’ sources and transmit that data to

output

60. What is the function of a latch in digital circuits? A. An asynchronous device to store state information B. An asynchronous device to transmit data C. A mechanism to detect falling edge of the clock D. None of the above

do not open this booklet until you are asked … · this question paper contains total of 60...

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