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This set of Communication Skill Multiple Choice Questions & Answers (MCQs) focuses on Communication Skill Set 4

Q1 | FM transmitting and receiving equipment as compared to AM equipment is
  • costly
  • cheaper
  • almost equally costly
  • none of the above
Q2 | An audio signal (say from 50 Hz to 10000 Hz) is frequency translated by a carrier having a frequency of 106 Hz. The values of initial (without frequency translation) and final (after frequency translation) fractional change in frequency from one band edge to the other are
  • 200 and 1.01
  • 200 and 10.01
  • 200 and 100.1
  • 200 and 200
Q3 | If in a broadcasting studio, a 1000 kHz carrier is modulated by an audio signal of frequency range 100-5000 kHz, the width of channel is __________ kHz.
  • 5
  • 4.9
  • 995
  • 10
Q4 | Which one of the following is analog?
  • pcm
  • pwm
  • delta modulation
  • differential pcm
Q5 | The disadvantage of FM over AM is that
  • high output power is needed
  • high modulating power is needed
  • noise is very high for high frequency
  • large bandwidth is required
Q6 | Which of the following is a digital modulation technique?
  • pcm
  • psk
  • dm
  • all
Q7 | Which of the following is used to generate PDM?
  • free running multi-vibrator
  • monostable multi-vibrator
  • jk flip-flop
  • schmitt trigger
Q8 | SSB can be generated by
  • filter method
  • phase cancellation method
  • good attenuation characteristics
  • all of the above
Q9 | A zero mean white Gaussian noise is passed through an ideal low pass filter of bandwidth 10 kHz. The output of the samples so obtained would be
  • correlated
  • statistically independent
  • uncorrelated
  • orthogonal
Q10 | What is the purpose of peak clipper circuits in radio transmitters?
  • to prevent overmodulation
  • to reduce bandwidth
  • to increase bandwidth
  • to regulate oscillator i/p voltage
Q11 | In case of low level amplitude modulation system, the amplifiers following the modulated stage must be
  • class c amplifiers
  • linear devices
  • non-linear devices
  • harmonic devices
Q12 | Under ordinary circumstances, impulse noise can be reduced in
  • fm only
  • am only
  • both am and fm
  • none of the above
Q13 | In case of frequency modulation, modulating voltage remains constant if the modulating frequency is lowered, then
  • amplitude of distant sidebands decreases
  • amplitude of distant sidebands increases
  • amplitude of distant sidebands remains constant
  • amplitude of distant sidebands first increases, then decreases
Q14 | If sampling is done at the rate of 10 kHz. The bandwidth required is
  • 35 khz
  • 70 khz
  • 10 khz
  • 1280 khz
Q15 | It is found that a ship to ship communication suffers from fading. This can be avoided by using
  • space diversity
  • frequency diversity
  • broad band antenna
  • directional antenna
Q16 | In practical commercial FM system, channel bandwidth is
  • 150 khz
  • 100 khz
  • 88 mhz
  • 108 mhz
Q17 | In EM waves, polarization
  • is always vertical in an isotropic medium
  • is caused by reflection
  • is due to transverse nature of waves
  • results from longitudinal nature of waves
Q18 | The maximum power output of a standard A earth station over the total band allocated to satellite communication is about
  • 0.5 kw
  • 8 kw
  • 20 kw
  • 50 kw
Q19 | PAM stands for
  • pulse analogue modulation
  • phase analogue modulation
  • pulse amplitude modulation
  • phase amplitude modulation
Q20 | The characteristic impedance of a twin wire feeder used for TV signals is about
  • 1000 ohm
  • 500 ohm
  • 300 ohm
  • 100 ohm
Q21 | In a FM receiver, amplitude limiter
  • amplifiers low frequency signals
  • reduces the amplitude of signals
  • eliminates any change in amplitude of received fm signals
  • none of the above
Q22 | A buffer amplifier is
  • a double-tuned amplifier
  • a high gain d.c. amplifier
  • a cathode follower stage
  • none of the above
Q23 | Leak type bias is used in plate modulated class C amplifier to
  • increase the bandwidth
  • prevent over modulation
  • prevent excessive grid current
  • prevent tuned circuit damping
Q24 | The direction of rotation of a CD is
  • clockwise
  • anticlockwise
  • clockwise or anticlockwise depending on frequency of data stored
  • mostly anticlockwise but some times clockwise
Q25 | One of the advantages of base modulation over collector modulation of a transistor class C amplifier is
  • improved efficiency
  • better linearity
  • high power output per transistor
  • the lower modulating power requirement