Q. In TV, video signals are transmitted through ?

  • (A) Frequency modulation
  • (B) Pulse modulation
  • (C) Amplitude modulation
  • (D) Phase modulation
πŸ’¬ Discuss
βœ… Correct Answer: (C) Amplitude modulation

Q. A carrier voltage is simultaneously modulated by two sine waves causing modulation indices of 0.4 and 0.3. the overall modulation index is ?

  • (A) 0.35
  • (B) 0.7
  • (C) 0.5
  • (D) Cannot be calculated unless the phase relations are known
πŸ’¬ Discuss
βœ… Correct Answer: (C) 0.5

Q. Which one of the following is used for the detection of AM-DSB-SC signal ?

  • (A) Ratio detector
  • (B) Foster-Seeley discriminator
  • (C) Product demodulator
  • (D) Balanced – slope detector
πŸ’¬ Discuss
βœ… Correct Answer: (C) Product demodulator

Q. Absorption of Ratio waves in atmosphere depends on ?

  • (A) Frequency of waves
  • (B) Distance from transmitter
  • (C) Polarization of waves
  • (D) Polarization of atmosphere
πŸ’¬ Discuss
βœ… Correct Answer: (A) Frequency of waves

Q. A 20kW carrier is sinusoid ally modulated by two carriers corresponding to a modulation index of 20% and 40 % respectively. The total radiated power is ?

  • (A) 25kW
  • (B) 17kW
  • (C) 15kW
  • (D) 22kW
πŸ’¬ Discuss
βœ… Correct Answer: (D) 22kW

Q. For which of the following reasons, amplitude modulation is used for broadcasting ?

  • (A) It is more immune to noise
  • (B) It use avoids receiver complexity
  • (C) It requires less transmitting power
  • (D) Only the positive peak of the carrier wave varies with the modulating signal
πŸ’¬ Discuss
βœ… Correct Answer: (B) It use avoids receiver complexity

Q. The input to a coherent detector is DSB-SC signal plus noise. The noise at the detector output is ?

  • (A) The in-phase component
  • (B) The Quadrature-component
  • (C) Zero
  • (D) The envelope
πŸ’¬ Discuss
βœ… Correct Answer: (C) Zero

Q. In amplitude modulation AM, if modulation index is more than 100% then ?

  • (A) Power of the wave increases
  • (B) Efficiency of transmission increases
  • (C) The wave gets distorted
  • (D) Band with increases
πŸ’¬ Discuss
βœ… Correct Answer: (C) The wave gets distorted

Q. Number of ‘side bands’ produced during A.M ?

  • (A) One
  • (B) Two
  • (C) Four
  • (D) unlimited
πŸ’¬ Discuss
βœ… Correct Answer: (B) Two

Q. In frequency modulation: ?

  • (A) Carrier signal amplitude varies with the amplitude of modulating signal
  • (B) Carrier signal amplitude varies with the frequency of modulating signal
  • (C) Carrier signal frequency varies with the frequency of modulating signal
  • (D) Carrier signal frequency varies with the amplitude of modulating signal
πŸ’¬ Discuss
βœ… Correct Answer: (C) Carrier signal frequency varies with the frequency of modulating signal

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