MCQOPTIONS
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MCQOPTIONS
This section includes 32 Mcqs, each offering curated multiple-choice questions to sharpen your Wireless Mobile Communications knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A product detector in AM systems is also called ___________ |
| A. | Envelope detector |
| B. | Differentiator |
| C. | Integrator |
| D. | Phase detector |
| Answer» E. | |
| 2. |
AM demodulation technique can be divided into _____ and _____ demodulation. |
| A. | Direct, indirect |
| B. | Slope detector, zero crossing |
| C. | Coherent, noncoherent |
| D. | Quadrature detection, coherent detection |
| Answer» D. Quadrature detection, coherent detection | |
| 3. |
FFSR in AM systems stands for ________ |
| A. | Feedforward signal regeneration |
| B. | Feedbackward signal regeneration |
| C. | Feedbackward system restoration |
| D. | Feedforward system restoration |
| Answer» B. Feedbackward signal regeneration | |
| 4. |
The RF bandwidth of AM is ____________ the maximum frequency contained in the modulating message signal. |
| A. | Equal |
| B. | Two times |
| C. | Four times |
| D. | Ten times |
| Answer» C. Four times | |
| 5. |
A percentage of modulation greater than ___________ will distort the message signal. |
| A. | 10% |
| B. | 25% |
| C. | 50% |
| D. | 100% |
| Answer» E. | |
| 6. |
Modulation index of an AM signal is ratio of __________ to the _______ |
| A. | Peak carrier amplitude, Peak message signal amplitude |
| B. | Peak message signal amplitude, Peak carrier amplitude |
| C. | Carrier signal frequency, Message signal frequency |
| D. | Message signal frequency, Carrier signal frequency |
| Answer» C. Carrier signal frequency, Message signal frequency | |
| 7. |
A 10 kW carrier is sinusoidally modulated by two carriers corresponding to a modulation index of 30% and 40% respectively. The total radiated power is |
| A. | 11.25 kW |
| B. | 12.5 kW |
| C. | 15 kW |
| D. | 17 kW |
| Answer» B. 12.5 kW | |
| 8. |
In a DSB-SC system with 100% modulation, the power saving is |
| A. | 100% |
| B. | 55% |
| C. | 75% |
| D. | 100% |
| Answer» C. 75% | |
| 9. |
A carrier is simultaneously modulated by two sine waves with modulation indices of 0.4 and 0.3. The resultant modulation index will be |
| A. | 1 |
| B. | 0.7 |
| C. | 0.5 |
| D. | 0.35 |
| Answer» D. 0.35 | |
| 10. |
A 2 MHz carrier is amplitude modulated by a 500 Hz modulating signal to a depth of 70%. If the unmodulated carrier power is 2 kW, the power of the modulated signal is |
| A. | 2.23 kW |
| B. | 2.36 Kw |
| C. | 1.18 kW |
| D. | 1.26 kW |
| Answer» B. 2.36 Kw | |
| 11. |
AM_DEMODULATION_TECHNIQUE_CAN_BE_DIVIDED_INTO_______AND_______DEMODULATION.?$ |
| A. | Direct, indirect |
| B. | Slope detector, zero crossing |
| C. | Coherent, noncoherent |
| D. | Quadrature detection, coherent detection |
| Answer» D. Quadrature detection, coherent detection | |
| 12. |
A_CARRIER_IS_SIMULTANEOUSLY_MODULATED_BY_TWO_SINE_WAVES_WITH_MODULATION_INDICES_OF_0.4_AND_0.3._THE_RESULTANT_MODULATION_INDEX_WILL_BE?$ |
| A. | 1.0 |
| B. | 0.7 |
| C. | 0.5 |
| D. | 0.35 |
| Answer» C. 0.5 | |
| 13. |
FFSR_IN_AM_SYSTEMS_STANDS_FOR_________?$ |
| A. | Feedforward signal regeneration |
| B. | Feedbackward signal regeneration |
| C. | Feedbackward system restoration |
| D. | Feedforward system restoration |
| Answer» B. Feedbackward signal regeneration | |
| 14. |
A product detector in AM systems is also called ______$ |
| A. | Envelope detector |
| B. | Differentiator |
| C. | Integrator |
| D. | Phase detector |
| Answer» E. | |
| 15. |
Non coherent detection requires the knowledge of transmitted carrier frequency and phase at the receiver. State whether True or False.$ |
| A. | True |
| B. | False |
| Answer» C. | |
| 16. |
In_a_DSB-SC_system_with_100%_modulation,_the_power_saving_is$ |
| A. | 100% |
| B. | 55% |
| C. | 75% |
| D. | 100% |
| Answer» B. 55% | |
| 17. |
AM system use only product detector for demodulation. They never use envelope detectors. State whether True or False. |
| A. | True |
| B. | False |
| Answer» C. | |
| 18. |
A 2 MHz carrier is amplitude modulated by a 500 Hz modulating signal to a depth of 70%. If the unmodulated carrier power is 2 kW, the power of the modulated signal i? |
| A. | 2.23 kW |
| B. | 2.36 Kw |
| C. | 1.18 kW |
| D. | 1.26 kW |
| Answer» D. 1.26 kW | |
| 19. |
Which of the following is a disadvantage of tone-in-band SSB system? |
| A. | High bandwidth |
| B. | Bad adjacent channel protection |
| C. | Effects of multipath |
| D. | Generation and reception of signal is complicated |
| Answer» E. | |
| 20. |
A modulating signal is amplified by a 80% efficiency amplifier before being combined with a 20 kW carrier to generate an AM signal. The required DC input power to the amplifier, for the system to operate at 100% modulation, would be |
| A. | 5 kW |
| B. | 8.46 kW |
| C. | 12.5 kW |
| D. | 6.25 kW |
| Answer» B. 8.46 kW | |
| 21. |
How is the performance of SSB AM systems in fading channels? |
| A. | Poor |
| B. | Best |
| C. | Good |
| D. | Average |
| Answer» B. Best | |
| 22. |
The aerial current of an AM transmitter is 18 A when unmodulated but increases to 20 A when modulated.The modulation index is |
| A. | 0.68 |
| B. | 0.73 |
| C. | 0.89 |
| D. | 0.95 |
| Answer» D. 0.95 | |
| 23. |
Single sideband AM systems occupy same bandwidth as of conventional AM systems. State whether True or False. |
| A. | True |
| B. | False |
| Answer» C. | |
| 24. |
An AM broadcast station operates at its maximum allowed total output of 50 kW with 80% modulation. The power in the intelligence part is |
| A. | 12.12 kW |
| B. | 31.12 kW |
| C. | 6.42 kW |
| D. | none of the mentioned |
| Answer» B. 31.12 kW | |
| 25. |
The RF bandwidth of AM is _____ the maximum frequency contained in the modulating message signal. |
| A. | Equal |
| B. | Two times |
| C. | Four times |
| D. | Ten times |
| Answer» C. Four times | |
| 26. |
Total sideband power is |
| A. | 4 W |
| B. | 8 W |
| C. | 16 W |
| D. | 2 W |
| Answer» B. 8 W | |
| 27. |
A percentage of modulation greater than ____ will distort the message signal. |
| A. | 10% |
| B. | 25% |
| C. | 50% |
| D. | 100% |
| Answer» E. | |
| 28. |
Total signal power is |
| A. | 208 W |
| B. | 204 W |
| C. | 408 W |
| D. | 416 W |
| Answer» B. 204 W | |
| 29. |
If the peak message signal amplitude is half the peak amplitude of the carrier signal, the signal is _____ modulated. |
| A. | 100% |
| B. | 2% |
| C. | 50% |
| D. | 70% |
| Answer» D. 70% | |
| 30. |
The modulation index is |
| A. | 20 |
| B. | 4 |
| C. | 0.2 |
| D. | 10 |
| Answer» C. 0.2 | |
| 31. |
Modulation index of an AM signal is ratio of _____ to the _______ |
| A. | Peak carrier amplitude, Peak message signal amplitude |
| B. | Peak message signal amplitude, Peak carrier amplitude |
| C. | Carrier signal frequency, Message signal frequency |
| D. | Message signal frequency, Carrier signal frequency |
| Answer» C. Carrier signal frequency, Message signal frequency | |
| 32. |
Carrier signal in modulation technique is _______ signal. |
| A. | High frequency |
| B. | Low frequency |
| C. | High amplitude |
| D. | Low amplitude |
| Answer» B. Low frequency | |