Communication Signal Processing MCQs

1. Which modulation technique is commonly used in FM radio broadcasting? A) Amplitude modulation (AM) B) Frequency modulation (FM) C) Phase modulation (PM) D) Pulse modulation (PM) Answer: B 2. What is the primary advantage of digital modulation techniques over analog modulation techniques? A) Higher bandwidth efficiency B) Simplicity in implementation C) Better noise immunity D) Lower power consumption Answer: C 3. Which of the following is a characteristic of phase-shift keying (PSK) modulation? A) It varies the amplitude of the carrier signal. B) It varies the frequency of the carrier signal. C) It varies the phase of the carrier signal. D) It combines amplitude and phase variations. Answer: C 4. Which modulation technique is used in digital subscriber line (DSL) communication? A) Amplitude modulation (AM) B) Frequency modulation (FM) C) Phase modulation (PM) D) Quadrature amplitude modulation (QAM) Answer: D 5. In frequency modulation (FM), what parameter varies according to the modulating signal? A) Amplitude B) Frequency C) Phase D) Wavelength Answer: B 6. Which modulation technique is used in Global System for Mobile communications (GSM)? A) Amplitude modulation (AM) B) Frequency modulation (FM) C) Phase modulation (PM) D) Gaussian minimum shift keying (GMSK) Answer: D 7. Which of the following is a characteristic of amplitude modulation (AM)? A) It varies the amplitude of the carrier signal. B) It varies the frequency of the carrier signal. C) It varies the phase of the carrier signal. D) It combines amplitude and phase variations. Answer: A 8. Which modulation technique is used in digital television broadcasting (DVB)? A) Quadrature amplitude modulation (QAM) B) Phase modulation (PM) C) Pulse amplitude modulation (PAM) D) Amplitude modulation (AM) Answer: A 9. Which of the following is not a digital modulation technique? A) Phase-shift keying (PSK) B) Quadrature amplitude modulation (QAM) C) Frequency modulation (FM) D) Orthogonal frequency-division multiplexing (OFDM) Answer: C 10. Which modulation technique is typically used in Wi-Fi (IEEE 802.11) communication? A) Amplitude modulation (AM) B) Frequency modulation (FM) C) Phase modulation (PM) D) Orthogonal frequency-division multiplexing (OFDM) Answer: D 11. What is the purpose of using error correction coding in digital communication systems? A) To increase the signal power B) To reduce bandwidth C) To improve data integrity and reliability D) To modulate the carrier signal Answer: C 12. Which of the following techniques is used to combine multiple signals into a composite signal for transmission? A) Demodulation B) Multiplexing C) Filtering D) Sampling Answer: B 13. Which of the following is a characteristic of orthogonal frequency-division multiplexing (OFDM)? A) It uses frequency modulation (FM) to vary carrier signals. B) It divides the spectrum into multiple orthogonal subcarriers. C) It varies the amplitude of the carrier signal. D) It combines amplitude and phase variations. Answer: B 14. Which modulation technique is used in Bluetooth communication? A) Frequency modulation (FM) B) Amplitude modulation (AM) C) Gaussian frequency shift keying (GFSK) D) Phase modulation (PM) Answer: C 15. In digital communication, what does the term “bit rate” refer to? A) The number of bits transmitted per unit time B) The frequency range of the transmitted signal C) The amplitude of the transmitted signal D) The modulation technique used Answer: A 16. Which of the following modulation techniques is used in satellite communication? A) Amplitude modulation (AM) B) Frequency modulation (FM) C) Phase modulation (PM) D) Quadrature phase-shift keying (QPSK) Answer: D 17. Which of the following is an advantage of phase modulation (PM) over amplitude modulation (AM)? A) Better noise immunity B) Higher bandwidth efficiency C) Lower power consumption D) Simplicity in implementation Answer: A 18. Which digital modulation technique is used in digital audio broadcasting (DAB)? A) Pulse code modulation (PCM) B) Amplitude modulation (AM) C) Frequency modulation (FM) D) COFDM (Coded orthogonal frequency-division multiplexing) Answer: D 19. Which modulation technique is used in deep-space communication for interplanetary missions? A) Amplitude modulation (AM) B) Frequency modulation (FM) C) Phase modulation (PM) D) Binary phase-shift keying (BPSK) Answer: D 20. What is the function of a demodulator in a communication system? A) To encode digital information onto a carrier signal B) To filter out noise from the received signal C) To convert analog signals to digital signals D) To recover the original message signal from a modulated carrier signal Answer: D 21. Which modulation technique is used in modern cellular communication systems such as LTE (Long-Term Evolution)? A) Amplitude modulation (AM) B) Frequency modulation (FM) C) Phase modulation (PM) D) Orthogonal frequency-division multiplexing (OFDM) Answer: D 22. What is the primary advantage of using quadrature amplitude modulation (QAM) in digital communication systems? A) Higher data transmission rates B) Lower power consumption C) Better noise immunity D) Simplicity in implementation Answer: A 23. Which of the following is a characteristic of frequency-shift keying (FSK) modulation? A) It varies the amplitude of the carrier signal. B) It varies the frequency of the carrier signal. C) It varies the phase of the carrier signal. D) It combines amplitude and phase variations. Answer: B 24. Which modulation technique is commonly used in underwater acoustic communication? A) Amplitude modulation (AM) B) Frequency modulation (FM) C) Phase modulation (PM) D) Binary phase-shift keying (BPSK) Answer: D 25. In digital communication, what does the term “multiplexing” refer to? A) Encoding multiple signals into a single signal B) Filtering out noise from a signal C) Modulating a carrier signal D) Converting analog signals to digital signals Answer: A 26. Which modulation technique is used in Digital Video Broadcasting (DVB-T) for terrestrial television? A) Amplitude modulation (AM) B) Frequency modulation (FM) C) Quadrature phase-shift keying (QPSK) D) Orthogonal frequency-division multiplexing (OFDM) Answer: D 27. Which of the following statements about digital modulation techniques is true? A) QPSK can transmit more bits per symbol compared to BPSK. B) QAM has lower bandwidth efficiency than PSK. C) FSK has better noise immunity than QAM. D) AM is more robust against channel impairments than FM. Answer: A 28. Which modulation technique is commonly used in Radio Frequency Identification (RFID) systems? A) Amplitude modulation (AM) B) Frequency modulation (FM) C) Phase modulation (PM) D) Binary phase-shift keying (BPSK) Answer: D 29. What is the function of a mixer in communication systems? A) To amplify signals B) To combine signals at different frequencies C) To filter out noise from signals D) To modulate the carrier signal Answer: B 30. Which of the following is a characteristic of differential phase-shift keying (DPSK) modulation? A) It directly modulates the amplitude of the carrier signal. B) It directly modulates the frequency of the carrier signal. C) It encodes data by changing the phase of the carrier signal relative to the previous symbol. D) It uses multiple carrier frequencies to transmit data. Answer: C 31. Which modulation technique is used in Near Field Communication (NFC)? A) Amplitude modulation (AM) B) Frequency modulation (FM) C) Phase modulation (PM) D) On-off keying (OOK) Answer: D 32. What is the primary advantage of using spread spectrum modulation techniques? A) Higher data transmission rates B) Improved security and resistance to interference C) Lower power consumption D) Simplicity in implementation Answer: B 33. Which modulation technique is commonly used in military communication systems for its robustness and security? A) Amplitude modulation (AM) B) Frequency modulation (FM) C) Phase modulation (PM) D) Spread spectrum modulation Answer: D

Communication Signal Processing MCQs

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