Company: Hindustan Aeronautics Limited

HAL electronics and electrical computer engg questions and answers, Semi conductors, Transformers,digital electronics objective type multiple choice questions and answers

1. ASK, PSK, FSK, and QAM are examples of ________ conversion.

A) digital-to-digital

C) analog-to-analog

D) analog-to-digital

2. AM and FM are examples of ________ conversion.

A) digital-to-digital

B) digital-to-analog

D) analog-to-digital

3. In QAM, both ________ of a carrier frequency are varied.

A) frequency and amplitude

B) phase and frequency

D) none of the above

4. If the baud rate is 400 for a QPSK signal, the bit rate is ________ bps.

A) 100

B) 400

D) 1600

5. If the bit rate for an ASK signal is 1200 bps, the baud rate is ________.

A) 300

B) 400

C) 600

6. If the bit rate for an FSK signal is 1200 bps, the baud rate is ________.

A) 300

B) 400

C) 600

7. If the bit rate for a 16-QAM signal is 4000 bps, what is the baud rate?

A) 300

B) 400

D) 1200

8. If the baud rate for a 64-QAM signal is 2000, what is the bit rate?

A) 300

B) 400

C) 1000

9. Given an AM radio signal with a bandwidth of 10 KHz and the highest-frequency component at 705 KHz, what is the frequency of the carrier signal?

B) 705 KHz

C) 710 KHz

D) Cannot be determined from given information

10. _______ conversion is the process of changing one of the characteristics of an analog signal based on the information in the digital data.

B) Analog-to-analog

C) Analog-to-digital

D) Digital-to-digital

11. Which of the following is not a digital-to-analog conversion?

B) PSK

C) FSK

12. In ________, the amplitude of the carrier signal is varied to create signal elements. Both frequency and phase remain constant.

B) PSK

C) FSK

D) QAM

13. In _________, the frequency of the carrier signal is varied to represent data. Both peak amplitude and phase remain constant.

B) PSK

D) QAM

14. In ________, the phase of the carrier is varied to represent two or more different signal elements. Both peak amplitude and frequency remain constant.

C) FSK

D) QAM

15. A constellation diagram shows us the __________ of a signal element, particularly when we are using two carriers (one in-phase and one quadrature).

B) amplitude and frequency

C) frequency and phase

D) none of the above

16. Quadrature amplitude modulation (QAM) is a combination of ___________.

C) PSK and FSK

D) none of the above

17. ________ uses two carriers, one in-phase and the other quadrature.

B) PSK

C) FSK

18. _________ conversion is the representation of analog information by an analog signal.

A) Digital-to-analog

C) Analog-to-digital

D) Digital-to-digital

19. Analog-to-analog conversion is needed if the available bandwidth is _______.

A) low-pass

C) either (a) or (b)

D) neither (a) nor (b)

20. Which of the following is not an analog-to-analog conversion?

A) AM

B) PM

C) FM

21. In _____ transmission, the carrier signal is modulated so that its amplitude varies with the changing amplitudes of the modulating signal.

B) PM

C) FM

D) none of the above

22. In _____ transmission, the frequency of the carrier signal is modulated to follow the changing voltage level (amplitude) of the modulating signal. The peak amplitude and phase of the carrier signal remain constant, but as the amplitude of the information signal changes, the frequency of the carrier changes correspondingly.

A) AM

B) PM

D) none of the above

23. In _____ transmission, the phase of the carrier signal is modulated to follow the changing voltage level (amplitude) of the modulating signal.

A) AM

C) FM

D) none of the above

24. In _______, the peak amplitude of one signal level is 0; the other is the same as the amplitude of the carrier frequency.

A) PSK

C) FSK

D) none of the above

25. How many carrier frequencies are used in BASK?

A) 2

C) 0

D) none of the above

26. How many carrier frequencies are used in BFSK?

B) 1

C) 0

D) none of the above

27. How many carrier frequencies are used in BPSK?

A) 2

C) 0

D) none of the above

28. How many carrier frequencies are used in QPSK?

B) 1

C) 0

D) none of the above

29. The constellation diagram of BASK has ______ dots.

B) 1

C) 0

D) none of the above

30. The constellation diagram of BPSK has ______ dots.

B) 1

C) 0

D) none of the above

31. The constellation diagram of QPSK has ______ dots.

A) 2

B) 1

D) none of the above

32. The constellation diagram of 16-QAM has ______ dots.

A) 4

C) 8

D) none of the above

33. The Federal Communications Commission (FCC) allows ______kHz for each AM station.

A) 5

C) 20

D) none of the above

34. The Federal Communications Commission (FCC) allows ______ kHz for each FM station.

A) 20

B) 100

C) 200

D) none of the above