Communication Systems – Multiple Choice Questions (MCQs)

61. What is the main function of an RF amplifier in a receiver?
- A. To amplify the weak incoming signal
- B. To change frequency
- C. To detect the message
- D. To filter out noise
62. The image frequency is a spurious signal that results in unwanted ________ in a superheterodyne receiver.
- A. Amplification
- B. Demodulation
- C. Frequency conversion
- D. Noise
63. A varactor diode is often used in FM modulators as a:
- A. Voltage-controlled capacitor
- B. Voltage-controlled resistor
- C. Current-controlled inductor
- D. Fixed capacitor
64. The noise bandwidth of a filter is always ________ its 3-dB bandwidth.
- A. Less than
- B. Greater than
- C. Equal to
- D. Independent of
65. What is the primary role of a detector/demodulator in a receiver?
- A. To separate the message signal from the carrier
- B. To amplify the signal
- C. To filter noise
- D. To convert electrical to electromagnetic waves
66. The critical frequency in ionospheric propagation is the maximum frequency at which a wave can be reflected back to earth by the ionosphere for ________ incidence.
- A. Normal
- B. Oblique
- C. Grazing
- D. Any
67. The skip distance in sky wave propagation is the minimum distance from the transmitter at which the sky wave is:
- A. Received
- B. Not received
- C. Reflected
- D. Absorbed
68. Bit error rate (BER) is a common performance metric for:
- A. Analog communication
- B. Digital communication
- C. Both analog and digital
- D. Optical communication
69. Coherent detection requires a ________ at the receiver that is synchronized with the carrier at the transmitter.
- A. Oscillator
- B. Mixer
- C. Local oscillator
- D. Phase-locked loop
70. Non-coherent detection is simpler to implement but generally has ________ performance compared to coherent detection.
- A. Better
- B. Worse
- C. Same
- D. Unpredictable
71. The main advantage of coherent detection is its improved:
- A. Simplicity
- B. Power efficiency
- C. Noise performance
- D. Bandwidth
72. In digital communication
- A. intersymbol interference (ISI) is caused by:
- B. Noise
- C. Channel distortion
- D. Quantization error

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AllInfoHub – MCQ Practice

Communication Systems – Multiple Choice Questions (MCQs)

61. What is the main function of an RF amplifier in a receiver?

62. The image frequency is a spurious signal that results in unwanted ________ in a superheterodyne receiver.

63. A varactor diode is often used in FM modulators as a:

64. The noise bandwidth of a filter is always ________ its 3-dB bandwidth.

65. What is the primary role of a detector/demodulator in a receiver?

66. The critical frequency in ionospheric propagation is the maximum frequency at which a wave can be reflected back to earth by the ionosphere for ________ incidence.

67. The skip distance in sky wave propagation is the minimum distance from the transmitter at which the sky wave is:

68. Bit error rate (BER) is a common performance metric for:

69. Coherent detection requires a ________ at the receiver that is synchronized with the carrier at the transmitter.

70. Non-coherent detection is simpler to implement but generally has ________ performance compared to coherent detection.

71. The main advantage of coherent detection is its improved:

72. In digital communication

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