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18th August 2014, 07:40 AM
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Join Date: Apr 2013
Re: BEL ECE Model Question paper

Bharat Electronics Limited (BEL) Electronics and Communication Engineering exam model paper, i am giving here:

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

A) digital-to-digital

B) digital-to-analog-Answer

C) analog-to-analog

D) analog-to-digital



2. AM and FM are examples of ________ conversion.

A) digital-to-digital

B) digital-to-analog

C) analog-to-analog-Answer

D) analog-to-digital



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

A) frequency and amplitude

B) phase and frequency

C) amplitude and phase-Answer

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

C) 800-Answer

D) 1600



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

A) 300

B) 400

C) 600

D) 1200-Answer



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

A) 300

B) 400

C) 600

D) 1200-Answer



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

A) 300

B) 400

C) 1000-Answer

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

D) 12000-Answer



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?

A) 700 KHz-Answer

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.

A) Digital-to-analog-Answer

B) Analog-to-analog

C) Analog-to-digital

D) Digital-to-digital



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

A) ASK

B) PSK

C) FSK

D) AM-Answer



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

A) ASK-Answer

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.

A) ASK

B) PSK

C) FSK-Answer

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.

A) ASK

B) PSK-Answer

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).

A) amplitude and phase-Answer

B) amplitude and frequency

C) frequency and phase

D) none of the above



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

A) ASK and FSK

B) ASK and PSK-Answer

C) PSK and FSK

D) none of the above



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

A) ASK

B) PSK

C) FSK

D) QAM-Answer



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

A) Digital-to-analog

B) Analog-to-analog-Answer

C) Analog-to-digital

D) Digital-to-digital



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

A) low-pass

B) band-pass-Answer

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

D) QAM-Answer



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

A) AM-Answer

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

C) FM-Answer

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

B) PM-Answer

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

B) OOK-Answer

C) FSK

D) none of the above



25. How many carrier frequencies are used in BASK?

A) 2

B) 1-Answer

C) 0

D) none of the above



26. How many carrier frequencies are used in BFSK?

A) 2-Answer

B) 1

C) 0

D) none of the above



27. How many carrier frequencies are used in BPSK?

A) 2

B) 1-Answer

C) 0

D) none of the above



28. How many carrier frequencies are used in QPSK?

A) 2-Answer

B) 1

C) 0

D) none of the above



29. The constellation diagram of BASK has ______ dots.

A) 2-Answer

B) 1

C) 0

D) none of the above



30. The constellation diagram of BPSK has ______ dots.

A) 2-Answer

B) 1

C) 0

D) none of the above


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