MCQOPTIONS
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MCQOPTIONS
This section includes 147 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A radio receiver is tuned to 750 kHz and its oscillator frequency is 925 kHz. The image frequency would be |
| A. | 1000 kHz |
| B. | 1100 kHz |
| C. | 1170 kHz |
| D. | 1125 kHz |
| Answer» C. 1170 kHz | |
| 2. |
If a radio receiver amplifies all the signal frequency equally well, it is said to have high |
| A. | Fidelity |
| B. | Sensitivity |
| C. | Selectivity |
| D. | Distortion |
| Answer» B. Sensitivity | |
| 3. |
For this RF Circuit, the correct statement is: |
| A. | IF Spectrum is inverted and image is at 2.780 GHz |
| B. | IF Spectrum is not inverted and image is at 2.780 GHz |
| C. | IF spectrum is inverted and image is at 2.360 GHz |
| D. | IF spectrum is not inverted and image is 2.220 GHz |
| Answer» C. IF spectrum is inverted and image is at 2.360 GHz | |
| 4. |
A superheterodyne AM broadcast receiver has an IF of 455 kHz. If it is tuned to a frequency of 700 kHz, the image frequency is |
| A. | 1610 kHz |
| B. | 1155 kHz |
| C. | 245 kHz |
| D. | 210 kHz |
| Answer» B. 1155 kHz | |
| 5. |
Decoding, storage, and interpretation are the process steps of ______ |
| A. | Transmission |
| B. | Reception |
| C. | Filtration |
| D. | Modulation |
| Answer» C. Filtration | |
| 6. |
Noise figure for an ideal receiver is ______ |
| A. | 0 |
| B. | 1 |
| C. | 0.1 |
| D. | 10 |
| Answer» C. 0.1 | |
| 7. |
In a superheterodyne receiver, if the intermediate frequency is 450 kHz and the signal frequency is 1000 kHz, then the local oscillator frequency and image frequency respectively are |
| A. | 1450 kHz and 100 kHz |
| B. | 550 kHz and 1900 kHz |
| C. | 1450 kHz and 1900 kHz |
| D. | 550 kHz and 1450 kHz |
| Answer» D. 550 kHz and 1450 kHz | |
| 8. |
In a typical AM receiver circuit, the oscillator frequency is |
| A. | Same as the signal frequency |
| B. | Always equal to 455 Hz |
| C. | Lower than the signal frequency by 455 kHz |
| D. | Higher than the signal frequency by 455 kHz |
| Answer» E. | |
| 9. |
In a broadcast superheterodyne receiver, having no RF amplifier, the IF = 455 kHz. What is the image frequency if the receiver is tuned to 1000 kHz? |
| A. | 1455 kHz |
| B. | 1910 kHz |
| C. | 545 kHz |
| D. | 2455 kHz |
| Answer» C. 545 kHz | |
| 10. |
Calculate the rejection ratio at 1000 kHz for a broadcast superheterodyne receiver having no RF amplifier. The loaded Q of the antenna coupling circuit is 100. Intermediate frequency is 455 kHz. |
| A. | 7.22 |
| B. | 7.87 |
| C. | 3.53 |
| D. | 138.6 |
| Answer» E. | |
| 11. |
In a radio receiver, which of the following stages does not need alignment ___________ |
| A. | TRF stage |
| B. | IF stage |
| C. | antenna input stage |
| D. | audio stage |
| Answer» E. | |
| 12. |
A receiver tunes signal from 550 KHz to 1600 KHz with an IF of 455 KHz. The frequency tuning range ratio for the oscillator section of the receiver is nearly |
| A. | 2.9 |
| B. | 2.05 |
| C. | 1.65 |
| D. | 1.3 |
| Answer» C. 1.65 | |
| 13. |
In a super heterodyne receiver arrange the following components sequentially from input to the output1. Antenna2. Mixer3. IF amplifier4. Audio amplifier |
| A. | 1, 2, 3 and 4 |
| B. | 4, 2, 3 and 1 |
| C. | 1, 3, 2 and 4 |
| D. | 4, 3, 2 and 1 |
| Answer» B. 4, 2, 3 and 1 | |
| 14. |
Boosting of higher frequency at the transmitter is done by using |
| A. | De-emphasis |
| B. | AGC circuit |
| C. | Pre-emphasis |
| D. | Armstrong method |
| Answer» D. Armstrong method | |
| 15. |
A Superheterodyne receiver with an intermediate frequency of 450 kHz is tuned to a signal of 1600 kHz. The image frequency is |
| A. | 2500 kHz |
| B. | 2050 kHz |
| C. | 1600 kHz |
| D. | 450 kHz |
| Answer» B. 2050 kHz | |
| 16. |
A coherent binary phase-shift-keyed (BPSK) transmitter operates at a bit rate of 20 Mbps. For a probability of error P(e) of 10-4 and given carrier-to-noise (C/N) density ratio of 8.8 dB, determine the energy of bit-to-noise (Eb/N0) density ratio for a receiver bandwidth equal to the minimum double-sided Nyquist bandwidth. |
| A. | 23 dB |
| B. | 2.3 dB |
| C. | 8.8 dB |
| D. | 0.88 dB |
| Answer» D. 0.88 dB | |
| 17. |
Image signal frequency in a superheterodyne receiver is given by |
| A. | fs + IF |
| B. | fs + 2IF |
| C. | fs - IF |
| D. | fs - 2IF |
| Answer» C. fs - IF | |
| 18. |
In a radio receiver, AGC works by |
| A. | Tuning the local oscillator |
| B. | Turning off the audio section in the absence of a received signal |
| C. | Adjusting the gain of RF and IF |
| D. | Limiting the signal level using a clipper in the audio section |
| Answer» D. Limiting the signal level using a clipper in the audio section | |
| 19. |
Noise figure of an amplifier does not depend on |
| A. | Bandwidth |
| B. | Output power |
| C. | power input |
| D. | None of the above |
| Answer» B. Output power | |
| 20. |
One of the main functions of the RF amplifiers in a super-heterodyne receiver is to |
| A. | Provide improved tracking |
| B. | Permit better adjacent channel rejection |
| C. | Increase the tuning range of the receiver |
| D. | Improve the rejection of the image frequency |
| Answer» E. | |
| 21. |
In a standard AM superheterodyne receiver, if the IF is 455 kHz and the high-side tuning is used, the local oscillator frequency must vary between. |
| A. | 885 kHz – 1585 kHz |
| B. | 85 kHz – 1145 kHz |
| C. | 1005 kHz – 2155 kHz |
| D. | 88 kHz – 108 kHz |
| Answer» D. 88 kHz – 108 kHz | |
| 22. |
For an FM receiver with an input signal-to-noise ratio of 29 dB, a noise figure of 4 dB and an FM improvement factor of 16 dB, the pre-detection and post-detection signal-to-noise ratios are |
| A. | 25 dB and 41 dB |
| B. | 30 dB and 49 dB |
| C. | 25 dB and 49 dB |
| D. | 30 dB and 41 dB |
| Answer» B. 30 dB and 49 dB | |
| 23. |
An unmodulated voltage 10 V effective is applied to a dioxide detector in which load resistance is 4 x 10¯⁵ ohms. A micrometer shows that the rectified DC current in this resistance is 30 A. The efficiency of detection is |
| A. | 34% |
| B. | 55.5% |
| C. | 68.8% |
| D. | 84.7% |
| Answer» E. | |
| 24. |
Statement 1:Diode is the most common device used for demodulation.Statement 2:A discriminator is a FM detector. |
| A. | Statement 1 is true but statement 2 is false |
| B. | Statement 1 is false but statement 2 is true |
| C. | Both the statements are true |
| D. | Both the statements are false |
| Answer» D. Both the statements are false | |
| 25. |
The image frequency of a superheterodyne receiver is |
| A. | independent of the frequency at which the receiver is tuned |
| B. | always outside the operating range of the receiver |
| C. | typical to FM receivers only |
| D. | not rejected by the IF tuned circuits |
| Answer» D. not rejected by the IF tuned circuits | |
| 26. |
RF amplifiers are used in radio receivers for |
| A. | improved image frequency rejection |
| B. | improved rejection of adjacent unwanted signals |
| C. | prevention of re-radiation of the local oscillator through the antenna of the receiver |
| D. | all of the above |
| Answer» E. | |
| 27. |
An unmodulated voltage 10 V effective is applied to a dioxide detector in which load resistance is 4 x 10¯⁵ ohms. A micrometer shows that the rectified DC current in this resistance is 30 A. The input resistance of the detector is |
| A. | 114 kW |
| B. | 336 kW |
| C. | 384 kW |
| D. | 455 kW |
| Answer» C. 384 kW | |
| 28. |
The function of an AM detector circuit is to |
| A. | rectify the input signal |
| B. | discard the carrier |
| C. | provide audio signal |
| D. | all of the above |
| Answer» E. | |
| 29. |
Most popular IF for receivers tuning to 540 to 1650 kHz is |
| A. | 433 kHz |
| B. | 455 kHz |
| C. | 545 kHz |
| D. | 555 kHz |
| Answer» C. 545 kHz | |
| 30. |
Transport lag usually exists in |
| A. | thermal systems |
| B. | hydraulic systems and thermal systems |
| C. | pneumatic systems |
| D. | thermal, hydraulic and pneumatic systems |
| Answer» E. | |
| 31. |
When a receiver has good blocking performance, this means that |
| A. | It does not suffer from double-spotting |
| B. | Its image frequency rejection is poor |
| C. | It is unaffected by AGC derived from nearby transmissions |
| D. | Its detector suffers from burnout |
| Answer» C. It is unaffected by AGC derived from nearby transmissions | |
| 32. |
The typical squelch circuit cuts off |
| A. | an audio amplifier when the carrier is absent |
| B. | RF interference when the signal is weak |
| C. | An IF amplifier when the AGC is maximum |
| D. | An IF amplifier when the AGC is minimum |
| Answer» B. RF interference when the signal is weak | |
| 33. |
Indicate the false statement. The superheterodyne receiver replaced the TRF receiver because the latter suffered from |
| A. | Gain variation over the frequency coverage range |
| B. | Insufficient gain and sensitivity |
| C. | Inadequate selectivity at high frequencies |
| D. | Instability |
| Answer» C. Inadequate selectivity at high frequencies | |
| 34. |
If a FET is used as the first AF amplifier in a transistor receiver, this will have the effect of |
| A. | Improving the effectiveness of the AGC |
| B. | Reducing the effect of negative-peak clipping |
| C. | Reducing the effect of noise at low modulation depths |
| D. | Improving the selectivity of the receiver |
| Answer» C. Reducing the effect of noise at low modulation depths | |
| 35. |
To prevent overloading of the IF amplifier in a receiver, one should use |
| A. | Squelch |
| B. | Variable sensitivity |
| C. | Variable selectivity |
| D. | Double conversion |
| Answer» C. Variable selectivity | |
| 36. |
Indicate the false statement. Noting that no carrier is transmitter with J3E, we see that |
| A. | The receiver cannot use a phase comparator for AFC |
| B. | Adjacent-channel rejection is more difficult |
| C. | Production of AGC is a rather complicated process |
| D. | The transmission is not compatible with A3E |
| Answer» C. Production of AGC is a rather complicated process | |
| 37. |
Three-point tracking is achieved with |
| A. | Variable selectivity |
| B. | The padder capacitor |
| C. | Double spotting |
| D. | Double conversion |
| Answer» C. Double spotting | |
| 38. |
An AM receiver uses a diode detector for demodulation. This enables it satisfactorily to receive |
| A. | Single-sideband, suppressed-carrier |
| B. | Single-sideband, reduced-carrier |
| C. | ISB |
| D. | Single-sideband, full-carrier |
| Answer» E. | |
| 39. |
A receiver has poor IF selectivity. It will therefore also have poor |
| A. | Blocking |
| B. | Double-spotting |
| C. | Diversion reception |
| D. | Sensitivity |
| Answer» B. Double-spotting | |
| 40. |
Show which of the following statements about the amplitude limiter is untrue: |
| A. | The circuit is always biased in class C, by virtue of the leak-type bias. |
| B. | When the input increases past the threshold of the limiting, the gain decreases to keep the output constant. |
| C. | The output must be tuned |
| D. | Leak-type bias must be used |
| Answer» B. When the input increases past the threshold of the limiting, the gain decreases to keep the output constant. | |
| 41. |
The local oscillator of a broadcast receiver is tuned to a frequency higher than the incoming frequency |
| A. | To help the image frequency rejection |
| B. | To permit easier tracking |
| C. | Because otherwise an intermediate frequency could not be produced |
| D. | To allow adequate frequency coverage without switching |
| Answer» E. | |
| 42. |
A superheterodyne receiver with an IF of 450 kHz is tuned to a signal at 1200 kHz. The image frequency is |
| A. | 750 kHz |
| B. | 900 kHz |
| C. | 1650 kHz |
| D. | 2100 kHz |
| Answer» E. | |
| 43. |
The controlled oscillator synthesizer is sometimes preferred over the direct one because |
| A. | It is a simpler piece of equipment |
| B. | Its frequency stability is better |
| C. | It does not require crystal oscillator |
| D. | It is relatively free of spurious frequency |
| Answer» E. | |
| 44. |
In a broadcast superheterodyne receiver, the |
| A. | Local oscillator operates below the signal frequency |
| B. | Mixer input must be tuned to the signal frequency |
| C. | Local oscillator frequency is normally double the IF |
| D. | RF amplifier normally works at 455 kHz above the carrier frequency |
| Answer» C. Local oscillator frequency is normally double the IF | |
| 45. |
The image frequency of a superheterodyne receiver |
| A. | Is created within the receiver itself |
| B. | Is due to insufficient adjacent channel rejection |
| C. | Is not rejected be the IF tuned circuits |
| D. | Is independent of the frequency to which the receiver is tuned |
| Answer» D. Is independent of the frequency to which the receiver is tuned | |
| 46. |
The frequency generated by each decade in a direct frequency synthesizer is much higher than the frequency shown; this is done to |
| A. | Reduce the spurious frequency problem |
| B. | Increase the frequency stability of the synthesizer |
| C. | Reduce the number of decades |
| D. | Reduce the number of crystals required |
| Answer» B. Increase the frequency stability of the synthesizer | |
| 47. |
One of the main functions of the RF amplifier in a superheterodyne receiver is to |
| A. | Provide improved tracking |
| B. | Permit better adjacent-channel rejection |
| C. | Increase the tuning range of the receiver |
| D. | Improve the rejection of the image frequency |
| Answer» E. | |
| 48. |
Indicate the false statement in connection with communications receivers. |
| A. | The noise limiter cuts off the receiver’s output during a noise pulse. |
| B. | A product demodulator could be used for the reception of Morse code. |
| C. | Double conversion is used to improve image rejection |
| D. | Variable sensitivity is used to eliminate selective fading |
| Answer» E. | |
| 49. |
Indicate which of the following statements about the advantages of the phase discriminator over the slope detector is false: |
| A. | Much easier alignment |
| B. | Better linearity |
| C. | Greater limiting |
| D. | Fewer tuned circuits |
| Answer» D. Fewer tuned circuits | |
| 50. |
One of the following cannot be used to demodulate SSB: |
| A. | Product detector |
| B. | Diode Balance modulator |
| C. | Bipolar transistor balanced modulator |
| D. | Complete phase-shift generator |
| Answer» D. Complete phase-shift generator | |