Communication Systems – MCQs

1. : What is the main purpose of a communication system?
(A) To increase data size
(B) To store signals
(C) To transmit information from one place to another
(D) To generate noise

2. : Which of the following is a type of analog modulation?
(A) FSK
(B) PSK
(C) AM
(D) QAM

3. : In Frequency Modulation (FM), the information is carried by:
(A) Amplitude variation
(B) Frequency variation
(C) Phase variation
(D) Pulse variation

4. : What is the bandwidth of an AM signal?
(A) Equal to the message signal
(B) Twice the message signal
(C) Half the message signal
(D) Zero

5. : Which of the following is not a modulation technique?
(A) AM
(B) FM
(C) PCM
(D) FFT

6. : The Nyquist rate for a signal of bandwidth B Hz is:
(A) B
(B) 2B
(C) B/2
(D) 4B

7. : What does SNR stand for?
(A) Signal to Noise Ratio
(B) Sound Noise Reduction
(C) Signal Number Rate
(D) Signal Network Receiver

8. : What is the unit of noise power?
(A) Volts
(B) Watts
(C) Hertz
(D) Amps

9. : What type of wave is used in satellite communication?
(A) Surface wave
(B) Ground wave
(C) Space wave
(D) Sky wave

10. : Which frequency range is used in mobile communication?
(A) 300 Hz to 3 kHz
(B) 3 kHz to 30 kHz
(C) 30 MHz to 3 GHz
(D) 3 GHz to 30 GHz

11. : In digital communication, what does a modem do?
(A) Translates data to binary
(B) Amplifies the signal
(C) Converts analog to digital and vice versa
(D) Stores data

12. : Which of the following is a baseband transmission?
(A) AM
(B) FM
(C) PCM
(D) QAM

13. : What type of antenna is used in television broadcasting?
(A) Dipole antenna
(B) Parabolic dish
(C) Horn antenna
(D) Loop antenna

14. : Which one is a digital modulation technique?
(A) AM
(B) FM
(C) PSK
(D) PWM

15. : The process of converting analog signals to digital is called:
(A) Modulation
(B) Demodulation
(C) Sampling
(D) Quantization

16. : A demodulator is used to:
(A) Transmit the signal
(B) Convert analog to digital
(C) Extract message signal from carrier
(D) Modulate the signal

17. : The minimum number of bits required to represent 256 signal levels is:
(A) 7
(B) 8
(C) 9
(D) 10

18. : What does QAM stand for?
(A) Quantized Amplitude Modulation
(B) Quadrature Amplitude Modulation
(C) Quick Analog Modulation
(D) Quality Amplitude Modulation

19. : Which modulation is most susceptible to noise?
(A) FM
(B) PM
(C) AM
(D) QAM

20. : The purpose of a bandpass filter in a communication system is to:
(A) Amplify noise
(B) Block signals
(C) Allow signals of a specific frequency range
(D) Convert signal to DC

21. : Which of these is a multiplexing technique?
(A) AM
(B) TDM
(C) FM
(D) PCM

22. : The term “carrier wave” refers to:
(A) The original message signal
(B) A wave used to carry information
(C) A noise signal
(D) A baseband signal

23. : The main function of a transducer in communication is to:
(A) Transmit signals
(B) Convert energy from one form to another
(C) Demodulate signals
(D) Filter signals

24. : What is the function of a repeater in communication systems?
(A) To generate signals
(B) To amplify and retransmit signals
(C) To convert analog signals to digital
(D) To switch the signals

25. : Which of the following is used for error detection in communication?
(A) Modulation
(B) Sampling
(C) Parity check
(D) Multiplexing