Question 1

Fourier analysis indicate that a square wave can be represented as

Accepted Answer

A)  a fundamental sine wave and odd harmonics
B)  a fundamental sine wave and even harmonics
C)  a fundamental sine wave and harmonics
D)  fundamental and subharmonic sine waves A

Question 2

Which of the following does not cause losses in optical fibre cables?

Accepted Answer

A)  stepped index operation
B)  impurities
C)  microbending
D)  attenuation in glass A

Question 3

To eliminate ghosts in the picture

Accepted Answer

A)  use a longer transmission line
B)  connect a booster
C)  change the antenna orientation of location
D)  twist the transmission line C

Question 4

The frequency range of 300 kHz to 3000 kHz is known as

Accepted Answer

A)  low frequency
B)  medium frequency
C)  high frequency
D)  very high frequency

Question 5

A woofer should be fed from the input through a

Accepted Answer

A)  low pass filter
B)  high pass filter
C)  band pass filter
D)  band stop filter

Question 6

An FM radio receiver which is tuned to a 91.6 MHz broadcast station may receive an image frequency of __________ MHz.

Accepted Answer

A)  102.3
B)  113
C)  70.2
D)  80.9

Question 7

VSB modulation is preferred in TV because

Accepted Answer

A)  it reduces the bandwidth requirement to half
B)  it avoids phase distortion at low frequencies
C)  it results in better reception
D)  none of the above

Question 8

When the length of antenna is a whole wavelength

Accepted Answer

A)  the radiation at right angles is zero
B)  the radiation at right angles is maximum
C)  the radiation is zero in all directions
D)  the radiation is maximum in all directions

Question 9

As per Shannon-Hartley theorem, a noise less Gaussian channel has

Accepted Answer

A)  zero capacity
B)  infinite capacity
C)  small capacity
D)  none of the above

Question 10

For attenuation of high frequencies we should use

Accepted Answer

A)  shunt capacitance
B)  series capacitance
C)  inductance
D)  resistance

Question 11

Which of the following statements is correct?

Accepted Answer

A)  convex lens has positive focal power and concave lens have negative focal power
B)  convex lens has negative focal power and concave lens have positive focal power
C)  all lens have positive focal power
D)  all lens have negative focal power

Question 12

For a given carrier wave, maximum undistorted power is transmitted when value of modulation is

Accepted Answer

A)  1
B)  0.8
C)  0.5
D)  0

Question 13

In Pulse Code Modulation system

Accepted Answer

A)  large bandwidth is required
B)  quantising noise can be overcome by companding
C)  quantising noise can be reduced by decreasing the number of standard levels
D)  suffers from the disadvantage of its incompatibly with tdm

Question 14

For telegraphy the most commonly used modulation system is

Accepted Answer

A)  fsk
B)  two tone modulation
C)  pcm
D)  single tone modulation

Question 15

In Modulation, "carrier" is

Accepted Answer

A)  resultant wave
B)  speech voltage to be transmitted
C)  voltage with constant frequency, phase or amplitude
D)  voltage for which frequency, phase or amplitude is varied

Question 16

Circular polarization

Accepted Answer

A)  is useful in reducing depolarization effect on received wave
B)  involves critical alignment of transmitting and receiving antenna
C)  is useful in discrimination between reception of adjacent beams
D)  none of the above

Question 17

A telephone channel requires a bandwidth of about

Accepted Answer

A)  1 khz
B)  3 khz
C)  10 khz
D)  50 khz

Question 18

The colour of an object is decided by

Accepted Answer

A)  the reflected colour
B)  the wavelength transmitted through it
C)  reflected colour for opaque object and wavelength transmitted through it for transparent objects
D)  none of the above

Question 19

A modem is classified as low speed if data rate handled is

Accepted Answer

A)  upto 100 bps
B)  upto 250 bps
C)  upto 400 bps
D)  upto 600 bps

Question 20

Commercial Frequency deviation of FM is

Accepted Answer

A)  70 khz
B)  75 khz
C)  80 khz
D)  65 khz

Exam 2: Communication and Radio Broadcasting