1. What is the fourth harmonic of fundamental frequency of 400Hz?

A. 100 Hz B. 4 KHz
C. 4 Hz D. 1.6 KHz

2. The function denoted by the waveform given below is

A. An even function B. An odd function

C. Unit step function D. Unit impulse function

3. The output of a linear time invariant system can be obtained from its unit impulse response function
and the input function by
A. Convolution B. Addition
C. Multiplication D. Autocorrelation

4. The system given by y(n) = x(n) + 1/x(n - 1) is:

A. Linear B. Causal
C. Both (a) and (b) D. None of the above

𝟐𝝅𝒏 𝟐𝝅𝒏
5. What is the minimum period of the discrete sequence 𝒆𝒋 +𝒆𝒋
𝟒 𝟔

A. 4 B. 6
C. 12 D. 24

6. Which of the following statements is FALSE

A. A stable system always produces bounded outputs for bounded inputs
B. A causal system is one for which the output for any discrete time instant n = 𝒏𝒐 depends on the
input for n <= 𝒏𝒐 only
C. Systems are classified as FIR and IIR based on the duration of unit impulse response
D. A system which gives zero output for zero input is always a linear system
7. Identify the waveform

A. Sawtooth Wave B. Triangular Wave

C. Ramp Signal Wave D. Step Function Wave

8. Identify the waveform,

A. SAW tooth wave B. Ramp Signal wave

C. Triangular wave D. Stop Faction Wave
9. Name the functions of the graphs a, b, c, d

A. a: f(x)= x; b: f(x)=|𝒙|; c: f(x) = 𝒆𝒙 ; d: f(x)= x+2

B. a: f(x)= x+1; b: f(x)= 𝒙𝟐 ; c: f(x) = log x; d: f(x)= x-2
C. a: f(x)= -x; b: f(x)= |𝒙|; c: f(x) = −𝒆𝒙 ; d: f(x)= x+2
D. a: f(x)= x; b: f(x)=|𝒙𝟐 |; c: f(x) = 𝒆𝒙 ; d: f(x)= x-2

−𝒕
10. The signal x(t) = te u(t) represents:
𝑻

A. Energy signal B. Power signal

C. Neither energy nor power D. None

11. In a discrete Linear Shift Invariant system the input sequence length is L, the impulse response
sequence length is M, the output sequence length N is
A. N = L+M-1 B. N = LM
C. N = 2L+M D. N = L +2M

12. The convolution f(n) * δ (n-3) is equal to

A. f(n-3) B. f(n+3)
C. f(3) D. f(n)

13. DSP stands for

A. Discrete Signal Processing B. Digital Signal Processing
C. Double Signal Processor D. None of the above
14. The period of the function sin ㅠ/4(t-1) is

A. 1/8s B. 8s
C. 4s D. 1/4s

15. The period of the signal X(t) = cos(2πt) cos(4πt) – sin(2πt) sin(4πt) is
A. 1/3 s B. 1/6 s
C. 1/8 s D. cannot be determined

16. Which of the following is false for a continuous time signal?

A. Any signal can be expressed as the sum of an odd and an even signals
B. Sum of two periodic signals is always periodic
C. Any periodic signal can be expressed as sum of sinusoidal signals
D. None of the above

17. In a superheterodyne receiver,

A. the IF stage has better selectivity than RF stage
B. the RF stage has better selectivity than IF stage
C. the RF stage has same selectivity than IF stage
D. none of above

18. The condition for achieving distortion-less demodulation of amplitude modulated signal using an
envelope detector is
A. <0/Modulation index <0 B. <1/Modulation index <1
C. >1/Modulation index >1 D. independent of modulation index

19. Coherent demodulation of FSK signal can be detected using,

A. correlation receiver B. bandpass filter and envelope detector
C. matched filter D. discriminator detection

20. Highest harmonic is 20 kHz in an analog data. The data has been digitized using e Find the rate at
which digital signal generated?
A. 240 kbps B. 120 kbps
C. 60 kbps D. 40 kbps

21. The maximum range of a transmitter depends on

A. its frequency B. its power
C. both its frequency and power D. none of above

22. Demodulation -
A. rectifies modulated signal B. is opposite of modulation
C. removes sidebands D. is performed at the transmitting station
23. In AM receiver, the oscillator frequency is,
A. Always equal to signal frequency B. Always equal to 455 KHz
C. Always lower than signal frequency D. Always higher than signal frequency

24. In commercial TV transmission in India picture and speech signals are modulated respectively as,
A. Picture - VSB, Speech-VSB B. Picture - VSB, Speech-SSB
C. Picture - VSB, Speech-FM D. Picture - FM, Speech-VSB

25. Most popular IF for receivers tuning to 540 to 1650 kHz is

A. 433 KHz B. 455 KHz
C. 545 KHZ D. 555 KHZ

26. A signal of maximum frequency of 10 kHz is sampled at Nyquist rate. The time interval between two
successive samples is
A. 50μs B. 100μs
C. 500μs D. 1000μs

27. The quality factor Q in a series resonant circuit with resonant frequency1000Hz and half power points
at 950Hz and 1050Hz is
A. 100 B. 10
C. 1 D. 0.5

28. Varactor diode are used as,

A. Voltage controlled capacitor B. Voltage controlled resistor
C. Voltage controlled inductor D. None of above

29. The aspect ratio in a TV receiver is

A. 3:2 B. 4:2
C. 4:3 D. 3:1

30. The function of AGC in radio receiver is

A. To attenuate the input signal
B. To amplify the input signal
C. To compensate for the fluctuations in the received signal strength
D. To reduce noise in the received signal

31. If the bandwidth of a band-pass filter increases:

A. Q decreases
B. the roll-off rate increases
C. the half-power frequency decreases
D. the centre frequency decreases
32. Which type of modulation is used for TV video transmission?
A. AM B. PM
C. FM D. VSB-AM

33. If a radio station is broadcasting at 96.7 MHz, then the wave length is approximately
A. 310 centimetres B. 3.1 meters
C. 310 meters D. 3.1 kilometre

34. Audio frequency range is

A. 20 Hz to 20 KHz B. 20 Hz to 3.1 KHz
C. 91.0 98.3 MHz D. 0-5.5 MHz

35. The frequency range of VHF is

A. 30 KHz-3 MHz B. 3 MHz-30 MHz
C. 30 MHz-300 MHz D. 300 MHz – 3.0 GHz

36. The frequency range of UHF is

A. 30 KHz-3 MHz B. 30 MHz-30 MHz
C. 30 MHz-300 MHz D. 300 MHz – 3.0 GHz

37. The Frequency of FM radio band is

A.200 to 298 MHz B. 93.5 to 122 MHz
C.51 to 98.3MHz. D. 87.5 to 108 MHz

38. Aliasing results in

A. Undersampling B. Oversampling
C. Perfect sampling D. Guard Band formation

39. A message signal bandlimited to 4k is transmitted through 256 level PCM system. The transmitted
bandwidth of the system is
A. 16 k B. 32 k
C. 64 k D. 128 k

40. The resonant frequency of an RF amplifier is 50 MHz and its bandwidth is 50 kHz. The Q factor will
be
A. 10 B. 100
C. 0.01 D. 0.1
41. In a superheterodyne receiver, the IF is 455 kHz, if it is tuned to 1200 kHz, the image frequency will
be
A. 1655 kHz B. 745 kHz
C. 2110 kHz D. 910 kHz

42. Communication satellite are allotted a bandwidth of 500 MHz. This can be increased by using
A. Frequency and polarisation reuse B. Time division multiplexing
C. Frequency division multiplexing D. Triple Modulator Redundancy

43. A system has a sampling rate of 50,000 samples per second. The maximum frequency of the signal it
can acquire and reconstruct is
A. 25 kHz B. 50 kHz
C. 100 kHz D. 10 kHz

44. A 2 kW carrier is to be modulated to a 90% level. The total transmitted power would be
A. 2.81 kW B. 3.62 kW
C. 1.4 kW D. None

45. The range of super-heterodyne receiver tuning when 𝒇𝑳𝑶 > 𝒇𝒄 with broadcast frequency ranges 540 to
1600 KHz
A. 85-1145 kHz B. 540-1600 kHz
C. 995-2055 kHz D. 1450-2510 kHz

46. An increase in modulation index leads to an increase in bandwidth in case of

A. AM B. FM
C. PM D. None

47. A carrier is modulated to a depth of 40%. The increased power is

A. 40% B. 20%
C. 16% D. 8%

48. In a 50% modulated signal, the carrier is suppressed for transmission. The saving in transmitter
power would be
A. 88.9% B. 11%
C. 72% D. 18%

49. The main advantage of PCM system is lower

A. bandwidth B. power
C. noise D. none of these
50. To transmit N signals each band limited to 𝒇𝒎 Hz by time division multiplexing will require a minimum
bandwidth of
A. 𝒇𝒎 B. 2𝒇𝒎
C. N 𝒇𝒎 D. 𝒇𝒎 /N

51. To satisfy the sampling theorem, a 100 Hz sine wave should be sampled at
A. 10 Hz B. 100 Hz
C. 200 Hz D. 50 Hz

52. An analog voltage is in the range of 0 to 8 V is divided in eight equal intervals for conversion to 3-bit
digital output. The maximum quantization error is
A. 0 V B. 0.5 V
C. 1 V D. 2 V

53. The frequency deviation produced in a VHF carrier by a signal of 100 Hz is 50 kHZ. The frequency
modulation index is
A. 100 radians B. 250 radians
C. 500 radians D. 750 radians

54. In an amplitude modulated system, a sinusoidal carrier signal of 1 MHz is modulated by a 10 kHz
sinusoidal signal. If the lower side band and the carrier are suppressed and if the amplitude
modulated signal is sampled for further processing, what should be the minimum sampling
frequency for base band sampling?
A. 1000 kHz B. 990 kHz
C. 1980 kHz D. 2020 kHz

55. What will be the modulation index of an amplitude modulator if carrier signal has amplitude of 100
V and frequency 1 MHz whereas modulating signal has amplitude of 20 V and frequency 10 kHz?
A. 0.01 B. 0.1
C. 0.2 D. 5

56. The bandwidth of a video signal is 4.5 MHz. The signal is to be transmitted using PCM with 1024
quantization levels. The minimum bit rate required for transmission is
A. 90 Mbps B. 45 Mbps
C. 4.5 Mbps D. 10 Mbps

57. Modulation is required

A. To transmit electrical signals over an antenna through free space
B. To improve the signal to noise ratio
C. To make the low frequency signals travel long distance
D. All the above
58. The signal given is z(t) = 5cos(2000πt+4π) + 8sin(6000πt)𝒆𝒋𝟏𝟎𝟎𝟎𝛑𝐭 + 12cos(4000πt-6π). The Nyquist rate
is:
A. 7000KHz B. 3500khz
C. 2000khz D. 4000kh

59. A communication channel with Additive White Gaussian Noise has a bandwidth of 4 kHz and SNR
of 31dB. Its channel capacity is
A. 2 kbps B. 20 kbps
C. 40 kbps D. 38kbps

60. In amplitude modulation, the modulation envelope has a peak value which is double the unmodulation
carrier value. What is the value of the modulation index?
A. 25% B. 50%
C. 75% D. 100%

61. Which of the following is false regarding the white noise?

A. White noise and an impulse function both have a similar magnitude spectrum.
B. It is a Gaussian noise signal.
C. Its frequency spectrum contains all frequency components but in unequal proportion.
D. Theoretically it has infinite power.

62. If the total power of an amplitude-modulated signal is 800 W, and the carrier power is 500 W, what is
the modulation index?
A. 1.925 B. 1.095
C. 1.238 D. 1.90

63. In a receiver, noise is usually developed at

A. Audio stage B. Receiving antenna
C. RF stage D. IF stage

64. An FM transmitter operates with a peak frequency deviation of 50 kHz. If the highes frequency in the
modulating signal is 15 kHz, what is the total bandwidth of the FM signal using Carson's rule?
A. 120 kHz B. 130 kHz
C. 150 kHz D. 200 kHz

65. Which of the following type of noise gains importance at low frequency?
A. Shot noise B. Flicker noise
C. Thermal noise D. Transit time noise
66. An audio signal is digitized using a 12-bit PCM. What is the signal-to-quantization noise ratio (SQNR)
for this system?
A. 74 Db B. 62 dB
C. 63 dB D. 70 dB

67. A TDM link has 20 signal channels and each channel is sampled at 7 kHz. If each sample is represented
by 8 bits and contains an additional bit for synchronization, find the total bit rate for the TDM link?
A. 695 kbps B. 888 kbps
C. 1260 kbps D. 1209 kbps

68. Beamwidth of an antenna depends upon

A. shape of radiation pattern B. dimensions
C. wavelength D. all of the above

69. The phenomenon of microwave signals following the curvature of earth is

A. Faraday effect B. Ducting
C. Wave tilt D. Tropospheric scatter

70. The RF receiver's ability to reject unwanted signal is called

A. Selectivity B. Sensitivity
C. SNR D. Efficiency

71. As the aperture area of antenna increases, gain

A. increases B. decreases
C. rernains constant D. behaves unpredictably

72. Directivity of an isotropic antenna

A. 𝟏⁄𝟐π B. 1
C. 75 D. infinity

73. A transponder is a satellite equipment which

A. receives a signal from Earth station and amplifies
B. changes the frequency of the received signal
C. retransmits the received signal
D. does all of the above-mentioned functions

74. A 20 m antenna gives a certain uplink gain at frequencies of 4/6 GHz. For getting same gain in the
20/30 GHz band, antenna size required is metre.
A. 100 B. 4
C. 1 D. 10
75. The approximate height of a geostationary satellite above the earth's surface is
A. 1600Km B. 16000 Km
C. 26000Km D. 36000 Km

76. Kepler's second law states

A. If 𝒕𝟐 − 𝒕𝟏 = 𝒕𝟒 − 𝒕𝟑 , then 𝑨𝟏𝟐 = 𝑨𝟑𝟒 B. If 𝒕𝟐 + 𝒕𝟏 = 𝒕𝟒 + 𝒕𝟑 , then 𝑨𝟏𝟐 = 𝑨𝟑𝟒
C. If 𝒕𝟐 /𝒕𝟏 = 𝒕𝟒 /𝒕𝟑 , then 𝑨𝟏𝟐 = 𝑨𝟑𝟒 D. None of the above

77. The frequency for satellite communication should be

A. more than the critical frequency B. less than the critical frequency
C. equal to the critical frequency D. none of the above

78. The first geostationary Satellite launched in 1965 was called __________
A. EARLY BIRD (Intelsat-1) B. ANIK
C. WESTAR D. MOLNIYA

79. In simplex channel, flow of data is

A. In both directions, but one at a time B. Always in both direction
C. Always in one direction D. None of the above

80. Which of the following devices is used for modulation & demodulation
A. Multiplexer B. Serial port
C. Modem D. Gate way

81. The advantages of FDMA over TDMA includes:

(1) Division is simpler
(2) Propagation delays are eliminated
(3) Linearity
(4) Cheaper filters with less complicated logic functions
A. (1), (2) and (3) are correct B. (1) and (2) are correct
C. (1) and (4) are correct D. All four are correct

82. ___________type of duplex communication is used by a mobile phone.

A. Half B. Full
C. Zero D. Both A. and B.
83. The handoff takes place in Mobile Assisted Handoff, when:
A. The power received by the mobile station from other base station is more than the serving
base station
B. The channel allocated is not available
C. The mobile station has no signal
D. All of the above

84. What is the full form of LASER?

A. Light Amplification by Stimulated Emission of Radiation
B. Light Activated Silicon Emission Rectifier
C. Light Amplified Semiconductor Emission Radiation
D. None of these

85. The main energy losses in an optical fibre consist of

A. Material loss B. Loss due to light scattering
C. Bend loss D. All the above

86. An optical fibre has a core refractive index of 1.40 and a cladding refractive index of 1.05. The
numerical aperture is
A. 0.8575 B. 0.9260
C. 0.3500 D. 0.1585

87. Bending of light wave as it passes between material of different optical density
A. Reflection B. Refraction
C. Scattering D. Polarization

88. The micro-bending losses are depend on

A. Diameter B. Core material
C. Refractive index D. Mode and wavelength

89. Which of the following is described by the concept of numerical aperture in an optical fibre?
A. Light scattering B. Light collection
C. Light dispersion D. Light polarization

90. Which law gives the relationship between refractive index of the dielectric?
A. Law of reflection B. Law of refraction (Snell's Law)
C. Millman's Law D. Huygen's Law
91. The light sources used in fibre optics communication are
A. LED's and Lasers B. Phototransistors
C. Xenon lights D. Incandescent

92. Light incident on fibers of angles__ the acceptance angle do not propagate into the fiber.
A. Less than B. Greater than
C. Equal to D. Less than and equal to

93. The ratio of speed of light in air to the speed of light in another medium is called as
A. Speed factor B. Dielectric constant
C. Reflection index D. Refraction index

94. A pulsed radar, operating at 3 GHz, having pulse width of 2 μsec receives an echo from a target 10
μsec after sending the signal. The approximate range of the target is
A. 300 m B. 1500 m
C. 3000 m D. 5000 m

95. What does MTI stand for in radar technology?

A. Magnetic Target Interceptor B. Mobile Tracking Instrument
C. Moving Target Indicator D. Multi-Target Identification

96. Antenna is an electrical device which converts

A. Electrical signals to electromagnetic waves
B. Electromagnetic waves to Electrical signals
C. Both a & b
D. None of the above

97. For an observer, the redshift happens when light or other electromagnetic radiation from an object is
increased in wavelength, or shifted to the red end of the spectrum. This phenomenon is due to
A. Change in speed of light B. Frequency division multiple access
C. Doppler Shift D. Frequency Shift Keying

98. Most of the weather radars use

A. circular polarization B. linear polarization
C. horizontal polarization D. vertical polarization

99. The minimum doppler shift is ___________

A. zero B. double of transmitter frequency
C. transmitter frequency D. half of transmitter frequency
100. The minimum range of radar is primarily determined by
A. The pulse width and the TR cell recovery time
B. The ATR cell recovery time
C. The overall height of the antenna
D. The peak power output of the radar transmitter

101. Given the pulse width of 8 microseconds and a duty cycle of 8%, determine the pulse repetition time
of a radar system.
A. 100 us B. 1 us
C. 1000 us D. 10 ms

102. What is the significant difference between MTI and pulse Doppler radar (PDR)?
A. MTI receives more clutter than PDR
B. PDR uses filter bank while MTI used analog delay line canceller
C. PDR receives more clutter than MTI
D. MTI uses high power whereas PDR uses low power amplifier