AP ECET ELECTRONICS AND COMMUNICATION ENGINEERING (ECE) Multiple Choice Questions (MCQs)

61. What is the primary purpose of modulation in communication systems?

• A) To reduce the bandwidth of the signal
• B) To increase the frequency of the signal
• C) To convert the signal to a form suitable for transmission
• D) To increase the power requirements of the transmitter

Answer: C

62. Which of the following is a type of analog modulation?

• A) PSK
• B) AM
• C) PCM
• D) Delta modulation

Answer: B

63. In Amplitude Modulation (AM), the modulation index is defined as the ratio of:

• A) Peak frequency to carrier frequency
• B) Peak amplitude to carrier amplitude
• C) Carrier amplitude to peak amplitude
• D) Carrier frequency to peak frequency

Answer: B

64. Which of the following modulation schemes provides the best noise immunity?

• A) AM
• B) FM
• C) PM
• D) ASK

Answer: B

65. What is the bandwidth requirement for Frequency Modulation (FM)?

• A) It is directly proportional to the carrier frequency
• B) It is independent of the modulation index
• C) It increases with modulation index
• D) It decreases with the modulation index

Answer: C

66. Which type of transmitter operates at a low level of power, typically used in FM radio?

• A) High-level transmitter
• B) Low-level transmitter
• C) SSB transmitter
• D) Pulse transmitter

Answer: B

67. Which of the following is the main function of a Superheterodyne receiver?

• A) To convert a high-frequency signal to a lower frequency
• B) To amplify the signal
• C) To detect the amplitude modulation
• D) To suppress unwanted frequencies

Answer: A

68. In AM receivers, what characteristic is used to improve the quality of reception?

• A) Selectivity
• B) Sensitivity
• C) Fidelity
• D) IMRR

Answer: A

69. Which of the following is the key factor in determining the choice of Intermediate Frequency (IF) in a receiver?

• A) Sensitivity
• B) Selectivity
• C) IMRR
• D) Fidelity

Answer: C

70. Which wave propagation type is used for long-distance communication, such as radio waves reaching distant locations?

• A) Ground wave
• B) Sky wave
• C) Space wave
• D) Surface wave

Answer: B

71. What is the main feature of Pulse Code Modulation (PCM)?

• A) It transmits a continuous analog signal
• B) It converts the analog signal into a discrete digital signal
• C) It modulates the signal using a carrier wave
• D) It is primarily used for video transmission

Answer: B

72. What is the primary advantage of Delta modulation over PCM?

• A) Lower bandwidth requirements
• B) Higher data rates
• C) Better noise immunity
• D) Simpler hardware requirements

Answer: A

73. In synchronous transmission, the transmission and reception are synchronized using:

• A) Start and stop bits
• B) A common clock
• C) Error-correcting codes
• D) A timing signal

Answer: B

74. What is the main advantage of Frequency Division Multiplexing (FDM) over Time Division Multiplexing (TDM)?

• A) FDM is used for analog signals, while TDM is used for digital signals
• B) TDM has better noise immunity than FDM
• C) FDM requires less bandwidth than TDM
• D) TDM supports more users than FDM

Answer: A

75. Which of the following multiple access techniques is used in GSM (Global System for Mobile Communications)?

• A) FDMA
• B) TDMA
• C) CDMA
• D) OFDMA

Answer: B