MCQOPTIONS
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MCQOPTIONS
This section includes 125 Mcqs, each offering curated multiple-choice questions to sharpen your Analog Communications knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Frequency modulation is equipped in all EDM instruments. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 2. |
If 10mm is the accuracy considered, what will be the maximum value of λ for 1/1000 part? |
| A. | 10000 m |
| B. | 10 cm |
| C. | 10 m |
| D. | 10000 cm |
| Answer» D. 10000 cm | |
| 3. |
Modulating wave can also be known as ______ |
| A. | Total wave |
| B. | Measuring wave |
| C. | Super wave |
| D. | Incubation wave |
| Answer» C. Super wave | |
| 4. |
Which can’t be done in high frequency zones? |
| A. | Phase comparison |
| B. | Super imposition of waves |
| C. | Distance measurement |
| D. | Wavelength measurement |
| Answer» B. Super imposition of waves | |
| 5. |
Which of the following is constant in the case of frequency modulation? |
| A. | Modulation |
| B. | Wavelength |
| C. | Amplitude |
| D. | Frequency |
| Answer» D. Frequency | |
| 6. |
Which of the following indicates the correct set of frequency employed in measuring process? |
| A. | 7*106 to 5*108 Hz |
| B. | 7.5*106 to 4.5*108 Hz |
| C. | 7.5*106 to 5.9*108 Hz |
| D. | 7.5*106 to 5*108 Hz |
| Answer» E. | |
| 7. |
Which of the following represents the correct set of modulation classification? |
| A. | Frequency, time period |
| B. | Frequency, amplitude |
| C. | Amplitude, wavelength |
| D. | Wavelength, frequency |
| Answer» C. Amplitude, wavelength | |
| 8. |
Lower frequency is not suitable in_________ |
| A. | Direct transmission |
| B. | Distance calculation |
| C. | Determination of wavelength |
| D. | Determination of frequency |
| Answer» B. Distance calculation | |
| 9. |
Modern phase techniques are capable of __________ |
| A. | Resolving modulation |
| B. | Resolving amplitude |
| C. | Resolving frequency |
| D. | Resolving wave length |
| Answer» E. | |
| 10. |
In amplitude modulation, which among the following is constant? |
| A. | Amplitude |
| B. | Frequency |
| C. | Wave length |
| D. | Time period |
| Answer» C. Wave length | |
| 11. |
In a PCM system, a five bit-encoder is used. If the difference between two consecutive levels is 1 V, then the range of the encoder is |
| A. | 0-31 V |
| B. | 0-30 V |
| C. | 1-32 V |
| D. | 1-30 V |
| Answer» B. 0-30 V | |
| 12. |
Automatic gain control is used |
| A. | To maintain the tuning correct |
| B. | To reduce the volume of loud passages of music |
| C. | To increase the amplification at high frequencies |
| D. | To maintain the same volume of the output when stations of different strength are received |
| Answer» E. | |
| 13. |
For a PM modulator with a deviation sensitivity, K = 2.5 rad/V and a modulating signal Vm(t) = 2 cos (2 π 2000 t), the peak phase deviation m will be |
| A. | 1.25 rad |
| B. | 2.5 rad |
| C. | 5.0 rad |
| D. | 7.5 rad |
| Answer» D. 7.5 rad | |
| 14. |
An analog voltage is in the range of 0 to 8 V. It is divided into 8 equal intervals for conversion to 3-bit digital output. The maximum quantization error is |
| A. | 0 V |
| B. | 0.5 V |
| C. | 1 V |
| D. | 2 V |
| Answer» C. 1 V | |
| 15. |
Consider the following statements comparing delta modulation (DM) with PCM system:DM requires1. A lower sampling rate2. A higher sampling rate3. A lower bandwidth4. Simple hardwareWhich one of the above statements are correct? |
| A. | 1 and 3 only |
| B. | 2 and 4 only |
| C. | 1, 3 and 4 |
| D. | 2, 3 and 4 |
| Answer» E. | |
| 16. |
Determine the bandwidth occupied by a sinusoidal frequency modulated carrier for which the modulation index is 2.4 |
| A. | 4.8 fm |
| B. | 6.8 fm |
| C. | 2.4 fm |
| D. | 3.8 fm |
| Answer» C. 2.4 fm | |
| 17. |
Determine the bandwidth required for an FM signal having frequency 2 kHz and maximum deviation 10 kHz. |
| A. | 16 kHz |
| B. | 32 kHz |
| C. | 24 kHz |
| D. | 8 kHz |
| Answer» D. 8 kHz | |
| 18. |
In case of a monolithic phase-locked loop, the equation of free running frequency of the voltage controlled oscillator is |
| A. | \({f_{out}} \cong \frac{{1.2\;}}{{2{R_1}{C_1}}}Hz,\) |
| B. | \({f_{out}} \cong \frac{{1.2\;}}{{{R_1}{C_1}}}Hz\) |
| C. | \({f_{out}} \cong \frac{{4\;}}{{1.2{R_1}{C_1}}}Hz\) |
| D. | \({f_{out}} \cong \frac{{1.2\;}}{{4{R_1}{C_1}}}Hz\) |
| Answer» E. | |
| 19. |
An FM signal contains intelligence in |
| A. | it's frequency variations |
| B. | it's amplitude variations |
| C. | both amplitude and frequency variations |
| D. | none of these |
| Answer» B. it's amplitude variations | |
| 20. |
Consider the following detector circuits.(a) Diode detector(b) Slope detector(c) Balanced slope detector(d) Ratio detectorArrange the above detectors in decreasing order of their circuit complexity: |
| A. | (d), (b), (c), (a) |
| B. | (a), (b), (c), (d) |
| C. | (c), (d), (b), (a) |
| D. | (d), (c), (b), (a) |
| Answer» E. | |
| 21. |
In an amplitude modulated system, if the total power is 600 W and the power in the carrier is 400 W. then the modulation index is |
| A. | 0.5 |
| B. | 0.75 |
| C. | 0.9 |
| D. | 1 |
| Answer» E. | |
| 22. |
Match List-l with List-II and select the correct answer using the code given below the lists :List - IList - II A. Pilot carrier 1. Delta modulation B. Tuned circuit 2. Frequency modulation C. Slope oveload 3. PCM D. A to D converter 4. Single sideband AM |
| A. | A - 3, B - 2, C - 1, D - 4 |
| B. | A - 4, B - 2, C - 1, D - 3 |
| C. | A - 3, B - 1, C - 2, D - 4 |
| D. | A - 4, B - 1, C - 2, D - 3 |
| Answer» C. A - 3, B - 1, C - 2, D - 4 | |
| 23. |
In a frequency modulation system, maximum frequency deviation allowed is 1000 and modulating frequency is 1 kHz. Determine modulation index β. |
| A. | 2 |
| B. | 2000 |
| C. | 1 |
| D. | 1000 |
| Answer» D. 1000 | |
| 24. |
For a Phase Lock Loop (PLL) with a Gilbert cell mixer based phase detector, to maintain lock, the phase error between incoming reference signal and VCO output must be maintained between |
| A. | 0 & π |
| B. | 0 & π/2 |
| C. | 0 & 2π |
| D. | π & 2π |
| Answer» B. 0 & π/2 | |
| 25. |
In time-division multiplexing, there are 8000 samples for a digital signal-0 channel that uses 8 kHz sample rate and 8 bit PCM code. The line speed will be: |
| A. | 56 kbps |
| B. | 64 kbps |
| C. | 76 kbps |
| D. | 84 kbps |
| Answer» C. 76 kbps | |
| 26. |
In FM, "M" stands for |
| A. | Multiplication |
| B. | Modulation |
| C. | Multilevel |
| D. | Modulate |
| Answer» C. Multilevel | |
| 27. |
A 5-bit encoder is used. Each level represents 1 V. On account of modulation, voltage involved is 27.39 V. The quantization error is |
| A. | 0.39 V |
| B. | 0.6 V |
| C. | 0.09 V |
| D. | 0 V |
| Answer» B. 0.6 V | |
| 28. |
Phase modulation is generally not used for transmission because |
| A. | It needs higher power |
| B. | it needs large Antenna Sizes |
| C. | It is complex for decoding |
| D. | It does not carry much information |
| Answer» D. It does not carry much information | |
| 29. |
In TDM systems, channel separation is done with the use of |
| A. | AND gates |
| B. | Bandpass filter |
| C. | Dfferentiator circuit |
| D. | Integrator circuit |
| Answer» B. Bandpass filter | |
| 30. |
A message signal m(t) = Am sin (2πfmt) is used to modulate the phase of a carrier Ac cos (2πfct) to get the modulated signal y(t) = Ac cos (2πfct + m(t)). The bandwidth of y(t) |
| A. | depends on Am but not on fm |
| B. | depends on fm but not on Am |
| C. | depends on both Am and fm |
| D. | does not depends on Am or fm |
| Answer» D. does not depends on Am or fm | |
| 31. |
In FM modulation, when the modulation index increases, the transmitted power is |
| A. | Increased |
| B. | Decreased |
| C. | Unchanged |
| D. | None of these |
| Answer» D. None of these | |
| 32. |
If the radiated power of AM transmitter is 10 KW, the power in the carrier for modulation index of 0.6 is nearly: |
| A. | 8.24 KW |
| B. | 9.26 KW |
| C. | 8.47 KW |
| D. | 9.6 KW |
| Answer» D. 9.6 KW | |
| 33. |
Match the following list : List - I List – II (a) Super heterodyne Receiver(i)Granular Noise(b)PCM(ii)Image frequency(c)Delta modulation(iii)Frequency discrimination(d)FM(iv)Quantization Noise |
| A. | (a) – (iii), (b) – (i), (c) – (i), (d) – (iv) |
| B. | (a) – (iii), (b) – (iv), (c) – (i), (d) – (ii) |
| C. | (a) – (ii), (b) – (i), (c) – (iv), (d) – (iii) |
| D. | (a) – (ii), (b) – (iv), (c) – (i), (d) – (iii) |
| Answer» E. | |
| 34. |
In an FM signal, there are |
| A. | no sidebands |
| B. | infinite number of sidebands |
| C. | two sidebands upper and lower |
| D. | none of these |
| Answer» C. two sidebands upper and lower | |
| 35. |
In microwave relay communication, the repeater is usually an amplifier for the amplification of |
| A. | Carrier signal |
| B. | Baseband signal |
| C. | Amplitude modulated IF signal |
| D. | Frequency modulated IF signal |
| Answer» E. | |
| 36. |
In a Pulse Code Modulated system, the number of bits is increased from 7 to 8 bits. The improvement in signal to quantization noise ratio will be |
| A. | 2 dB |
| B. | 4 dB |
| C. | 6 dB |
| D. | 8 dB |
| Answer» D. 8 dB | |
| 37. |
Carson’s rule is (with symbols having their standard meaning) |
| A. | B = 2 DW |
| B. | B = 2 (D + 1) W |
| C. | B = √2 (D + 1) W |
| D. | B = √2 DW |
| Answer» C. B = √2 (D + 1) W | |
| 38. |
A binary channel with capacity 36 kbit/sec is available for PCM voice transmission. If the signal is band-limited to 3.2 kHz, then the appropriate values of quantizing level and the sampling frequency will be, respectively |
| A. | 32, 3.6 kHz |
| B. | 64, 7.2 kHz |
| C. | 64, 3.6 kHz |
| D. | 32, 7.2 kHz |
| Answer» E. | |
| 39. |
In Frequency Modulation scheme, the maximum frequency is 50 KHz. The frequency sensitivity is 1.5 KHz/V and modulating signal has an amplitude of 10 V. Determine the percentage modulation. |
| A. | 30% |
| B. | 50% |
| C. | 60% |
| D. | 75% |
| Answer» B. 50% | |
| 40. |
In TV, an electrical disturbance (noise) affects |
| A. | neither the video nor the audio signals |
| B. | only the audio signals |
| C. | both the video and audio signals |
| D. | only the video signals |
| Answer» E. | |
| 41. |
In an ADC, over sampling is a technique used to |
| A. | reduce the effect of input noise |
| B. | improve conversion clock stability |
| C. | reduce quantization noise |
| D. | improve power supply rejection ratio |
| Answer» D. improve power supply rejection ratio | |
| 42. |
Consider the following statements regarding Time-Division Multiplexing (TDM):1. The information from different measuring points is transmitted serially on the same communication channel.2. It involves the transmission of data samples rather than continuous data transmission.3. It is especially useful when telemetering fast-changing, high bandwidth data.Which of the above statements are valid in respect to TDM? |
| A. | 1, 2 and 3 |
| B. | 1 and 3 only |
| C. | 1 and 2 only |
| D. | 2 and 3 only |
| Answer» D. 2 and 3 only | |
| 43. |
In an amplitude modulated wave, the value of Emax is 10V and Emin is 5V, then percentage of modulation will be |
| A. | 2% |
| B. | 33.3% |
| C. | 50% |
| D. | 75% |
| Answer» C. 50% | |
| 44. |
A PAM source generates four symbols 3 V, 1 V, -1 V and -3 V with probability of p(3) = p(-3) = 0.2 and p(1) = p(-1) = 0.3 respectively. The variance for the source will be |
| A. | 4.2 V |
| B. | 3.2 V |
| C. | 3.6 V |
| D. | 4.6 V |
| Answer» B. 3.2 V | |
| 45. |
In a PLL |
| A. | Capture range = Lock range ≠ Free running frequency |
| B. | Capture range = Look range = Free running frequency |
| C. | Capture range > Lock range |
| D. | Capture range < Lock range |
| Answer» E. | |
| 46. |
Limiter circuit is not needed in the following detector: |
| A. | Foster - Seeley discriminator |
| B. | Balanced slope |
| C. | Ratio detector |
| D. | None |
| Answer» D. None | |
| 47. |
In a frequency modulated (FM) system, when the audio frequency is 500 Hz and the audio frequency voltage is 2.4 V, the frequency deviation δ is 4.8 kHz. If the audio frequency voltage is now increased to 7.2 V then what is the new value of deviation? |
| A. | 0.6 kHz |
| B. | 3.6 kHz |
| C. | 12.4 kHz |
| D. | 14.4 kHz |
| Answer» E. | |
| 48. |
Following is / are a property / properties of quantization |
| A. | It is an nonlinear process |
| B. | It is an irreversible process |
| C. | It maps a larger set of input values to a smaller set |
| D. | All of these |
| Answer» E. | |
| 49. |
In a synchronous TDM, there are four inputs and data rate of each input connection is 3 kbps. If 1 bit at a time is multiplexed, what is the duration of each frame? |
| A. | 0.02 ms |
| B. | 0.03 ms |
| C. | 0.33 ms |
| D. | 0.22 ms |
| Answer» D. 0.22 ms | |
| 50. |
Match the following list : List - I List - II(a)Mach - Zehnder(i)Direct - modulation(b)On-Off Keying(ii)Stimulated emission(c)SRS(iii)Pulse broadening(d)Dispersion(iv)Indirect modulator |
| A. | (a) – (iv), (b) – (ii), (c) – (iii), (d) – (i) |
| B. | (a) – (iv), (b) – (i), (c) – (ii), (d) – (iii) |
| C. | (a) – (i), (b) – (ii), (c) – (iii), (d) – (iv) |
| D. | (a) – (ii), (b) – (i), (c) – (iii), (d) – (iv) |
| Answer» C. (a) – (i), (b) – (ii), (c) – (iii), (d) – (iv) | |