Basic concepts of modulation and demodulation MCQs

What is modulation in a communication system?
A. Suppressing unwanted noise from a signal
B. Varying a carrier wave to encode information
C. Amplifying a weak signal
D. Converting analog signals to digital

Answer: B
Which of the following is NOT a type of modulation?
A. Amplitude Modulation (AM)
B. Frequency Modulation (FM)
C. Phase Modulation (PM)
D. Rectified Modulation (RM)

Answer: D
Which of the following is the main advantage of modulation?
A. Reduces bandwidth requirement
B. Enables long-distance signal transmission
C. Eliminates noise completely
D. Simplifies signal encoding

Answer: B
In amplitude modulation (AM), the modulating signal affects the:
A. Frequency of the carrier wave
B. Amplitude of the carrier wave
C. Phase of the carrier wave
D. Bandwidth of the carrier wave

Answer: B
Frequency modulation (FM) involves varying the:
A. Amplitude of the carrier wave
B. Frequency of the carrier wave
C. Phase of the carrier wave
D. Wavelength of the carrier wave

Answer: B
In phase modulation (PM), the modulating signal causes variations in the:
A. Frequency of the carrier wave
B. Amplitude of the carrier wave
C. Phase of the carrier wave
D. Power of the carrier wave

Answer: C
Which type of modulation is least susceptible to noise?
A. Amplitude Modulation (AM)
B. Frequency Modulation (FM)
C. Phase Modulation (PM)
D. Pulse Modulation

Answer: B
Which type of modulation is used in AM radio broadcasting?
A. Frequency Modulation
B. Amplitude Modulation
C. Phase Modulation
D. Pulse Modulation

Answer: B
The bandwidth requirement for an AM signal is:
A. Equal to the carrier frequency
B. Twice the highest frequency of the modulating signal
C. Half the highest frequency of the modulating signal
D. Independent of the modulating signal

Answer: B
Which type of modulation has the largest bandwidth requirement?
A. AM
B. FM
C. PM
D. Both FM and PM

Answer: D
Demodulation is the process of:
A. Encoding information into a carrier wave
B. Extracting the original information signal from a modulated carrier wave
C. Amplifying a weak signal
D. Reducing the noise in a signal

Answer: B
Which of the following devices is used for AM demodulation?
A. Phase-locked loop (PLL)
B. Envelope detector
C. Frequency discriminator
D. Quadrature detector

Answer: B
FM signals are demodulated using:
A. Frequency discriminators or PLL
B. Envelope detectors
C. Rectifiers
D. Filters

Answer: A
The role of a demodulator in a communication system is to:
A. Filter noise from the signal
B. Convert a digital signal into an analog signal
C. Recover the original information signal from the carrier wave
D. Enhance the signal power

Answer: C
Which modulation technique is commonly used in TV broadcasting?
A. AM
B. FM
C. PM
D. QAM

Answer: D
Which of the following systems uses frequency modulation (FM)?
A. Longwave radio
B. FM radio broadcasting
C. Morse code transmission
D. AM radio broadcasting

Answer: B
Phase modulation (PM) is commonly used in:
A. AM radio broadcasting
B. GPS communication
C. Wi-Fi networks
D. Long-distance telephony

Answer: C
Which modulation technique encodes both amplitude and phase into a single signal?
A. AM
B. FM
C. PM
D. Quadrature Amplitude Modulation (QAM)

Answer: D
In digital communication, which modulation technique is widely used?
A. ASK (Amplitude Shift Keying)
B. PSK (Phase Shift Keying)
C. FSK (Frequency Shift Keying)
D. All of the above

Answer: D
Which modulation technique is used in cellular networks for efficient bandwidth utilization?
A. QAM
B. AM
C. PM
D. SSB (Single Sideband Modulation)

Answer: A

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