MCQOPTIONS
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MCQOPTIONS
This section includes 35 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. |
Following are the modulation schemes:(i) WDM(ii) CWDM(iii) DWDMArrange their adjacent channel bandgap in ascending order. The correct sequence is: |
| A. | (i), (ii), (iii) |
| B. | (ii), (i), (iii) |
| C. | (iii), (ii), (i) |
| D. | (ii), (iii), (i) |
| Answer» D. (ii), (iii), (i) | |
| 2. |
On which of the following frequencies does a Wi-Fi network work? |
| A. | 2.4 MHz |
| B. | 5 MHz |
| C. | 10 GHz |
| D. | 5 GHz |
| Answer» E. | |
| 3. |
Given f(t) = 3e-4tu(t). Its Fourier transform F(ω) at ω = 4 is |
| A. | \(\frac{1}{{1 + j}}\) |
| B. | \(\frac{{\frac{3}{4}}}{{1 + j}}\) |
| C. | \(\frac{1}{{1 + \frac{4}{3}j}}\) |
| D. | \(\frac{{\frac{4}{3}}}{{1 + \frac{4}{3}j}}\) |
| Answer» C. \(\frac{1}{{1 + \frac{4}{3}j}}\) | |
| 4. |
In case of which of the following, an increase on the modulation index leads to increase in bandwidth |
| A. | PM |
| B. | FM |
| C. | AM |
| D. | Both (1) and (2) |
| Answer» E. | |
| 5. |
Assertion (A) : The problem of interference is solved by translating the message singles to different radio frequencies.Reason (R): The signals from various sources transmitted through open space cause interference and no useful message is passed to the receive. |
| A. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
| B. | Both (A) and (R) are true, but (R) is not the correct explanation of (A) |
| C. | (A) is true, but (R) is false |
| D. | (A) false, but (R) is true. |
| Answer» B. Both (A) and (R) are true, but (R) is not the correct explanation of (A) | |
| 6. |
Identify the disadvantage of Bluetooth technologies from the given options |
| A. | Used for voice and data transfer |
| B. | Low power consumption |
| C. | Affordable rates |
| D. | Lower security |
| Answer» E. | |
| 7. |
MODEM is used for |
| A. | Modulator at transmitting side and detector at the receiving side |
| B. | which deals with analog signals and show digital information |
| C. | Modulator at receiving side and detector at the transmitting side |
| D. | a device which deals with digital signals only |
| Answer» C. Modulator at receiving side and detector at the transmitting side | |
| 8. |
A message m(t) bandlimited to the frequency fm has a power of Pm. The power of the output signal in the figure is |
| A. | \(\frac{{\left( {Pm\cos \theta } \right)}}{2}\) |
| B. | \(\frac{{Pm\,{{\sin }^2}\theta }}{2}\) |
| C. | \(\frac{{Pm}}{4}\) |
| D. | \(\frac{{Pm\,{{\cos }^2}\theta }}{4}\) |
| Answer» E. | |
| 9. |
Consider the following types of modulation:1. Amplitude modulation2. Frequency modulation3. Phase modulation4. Pulse modulationWhich of the above modulation are used for telecasting TV programs? |
| A. | 2 and 3 |
| B. | 3 and 4 |
| C. | 1 and 2 |
| D. | 1 and 4 |
| Answer» D. 1 and 4 | |
| 10. |
In the process of modulation |
| A. | Some characteristics of a high frequency sine wave are varied in accordance with the instantaneous value of a low frequency signal |
| B. | Parameters of carrier wave are held constant |
| C. | For proper and efficient radiation, the receiving antennas should have heights comparable to half-wavelength of the single received |
| D. | The signal is converted first within the range of 10 Hz to 20 Hz |
| Answer» B. Parameters of carrier wave are held constant | |
| 11. |
Consider the 2 Statement:1. An odd and imaginary signal always has an odd and imaginary Fourier transform.2. The convolution of an odd Fourier transform with an even Fourier transform is always even.Which of the above statements is/are true: |
| A. | None |
| B. | 1 and 2 |
| C. | 1 |
| D. | 2 |
| Answer» B. 1 and 2 | |
| 12. |
During the heterodyne process in the receiver, the modulation of the signal __________ |
| A. | decreases |
| B. | remains unaffected |
| C. | increases |
| D. | is eliminated |
| Answer» C. increases | |
| 13. |
In a modulation system, if modulating frequency is doubled, the modulation index also becomes double, the system is |
| A. | FM |
| B. | AM |
| C. | PM |
| D. | Both FM and AM |
| Answer» D. Both FM and AM | |
| 14. |
In communication systems, modulation is the process of |
| A. | Improving frequency stability of transmitter |
| B. | Combining signal and radio frequency waves |
| C. | Generating constant frequency radio waves |
| D. | Reducing distortion RF waves |
| Answer» C. Generating constant frequency radio waves | |
| 15. |
Calculate the modulation percentage if the modulating signal is 8 V and carrier is of 12 V? |
| A. | 50 |
| B. | 67 |
| C. | 150 |
| D. | 33 |
| Answer» C. 150 | |
| 16. |
If a total of 33 MHz of bandwidth is allocated to a particular FDD cellular telephone system which uses two 25 kHz simplex channels to provide full duplex voice and control channels, compute the number of channels available per cell if a system uses 4-cell reuse |
| A. | 55 |
| B. | 660 |
| C. | 95 |
| D. | 165 |
| Answer» E. | |
| 17. |
In which modulation discrete values of carrier frequencies is used to transmit binary data ? |
| A. | Phase Shift Keying |
| B. | Amplitude Shift Keying |
| C. | Frequency Shift Keying |
| D. | Disk Shift Keying |
| Answer» D. Disk Shift Keying | |
| 18. |
Consider a system shown in the figure. Let X(f) and Y(f) denote the Fourier transforms of x(t) and y(t) respectively. The ideal HPF has the cut-off frequency 10 KHz.The positive frequencies where Y(f) has spectral peaks are |
| A. | 1 KHz and 24 KHz |
| B. | 2 KHz and 24 KHz |
| C. | 1 KHz and 14 KHz |
| D. | 2 KHz and 14 KHz |
| Answer» C. 1 KHz and 14 KHz | |
| 19. |
Modulation has a number of advantages. Which one of the following is not correct? |
| A. | Efficient transmission |
| B. | Reduction in noise and interference |
| C. | Overcomes hardware limitations |
| D. | Requires higher power transmitter |
| Answer» E. | |
| 20. |
Radio channel used for transmission of information from the base station to the mobile is called: |
| A. | Reverse Channel |
| B. | Page |
| C. | Handoff |
| D. | Forward Channel |
| Answer» E. | |
| 21. |
In Direct Broadcast System (DSB), |
| A. | MPEG-2 is used for video compression |
| B. | MPEG-2 is used for video enhancing |
| C. | MPEG-2 is used for audio compression |
| D. | None of these |
| Answer» C. MPEG-2 is used for audio compression | |
| 22. |
Modulation is required |
| A. | To transmit electrical signals over an antenna through free space |
| B. | To improve the signal to noise ratio |
| C. | To make the low frequency signals travel long distance |
| D. | All of the above |
| Answer» E. | |
| 23. |
The minimum height of antenna required for transmission in terms of ? is ________ |
| A. | 3?⁄2 |
| B. | ?⁄4 |
| C. | 2? |
| D. | ? |
| Answer» C. 2? | |
| 24. |
Medium which sends information from source to receiver is called ________ |
| A. | Transmitter |
| B. | Transducer |
| C. | Loudspeaker |
| D. | Channel |
| Answer» E. | |
| 25. |
Amplitude Modulation suffers from ________ |
| A. | Side-band Suppression |
| B. | IntraPulse Modulation |
| C. | Cross Modulation |
| D. | Carrier Suppression |
| Answer» D. Carrier Suppression | |
| 26. |
Telephones send information through wires in form of ________ |
| A. | radio signals |
| B. | electrical signal |
| C. | electromagnetic waves |
| D. | microwaves |
| Answer» C. electromagnetic waves | |
| 27. |
Cell phones sent information in form of ________ |
| A. | microwaves |
| B. | electrical signals |
| C. | infrared Waves |
| D. | radio waves |
| Answer» E. | |
| 28. |
AVC stands for ________ |
| A. | Abrupt Voltage Control |
| B. | Audio Voltage Control |
| C. | Automatic Volume Control |
| D. | Automatic Voltage Control |
| Answer» D. Automatic Voltage Control | |
| 29. |
What is the role of Amplitude limiter in FM receiver? |
| A. | Filteration |
| B. | Adjust the gain of receiver |
| C. | Amplify a weaker signal |
| D. | Demodulate a signal |
| Answer» E. | |
| 30. |
What is Carrier swing? |
| A. | Frequency deviation |
| B. | Width of sideband |
| C. | Instantaneous frequency |
| D. | Total variation in frequency |
| Answer» E. | |
| 31. |
A function f(x) is even, when? |
| A. | f(x) = -f(x) |
| B. | f(x) = f(-x) |
| C. | f(x) = -f(x)f(-x) |
| D. | f(x) = f(x)f(-x) |
| Answer» C. f(x) = -f(x)f(-x) | |
| 32. |
Relationship between amplitude and frequency is represented by ________ |
| A. | Time-domain plot |
| B. | Phase-domain plot |
| C. | Frequency-domain plot |
| D. | Amplitude-domain plot |
| Answer» D. Amplitude-domain plot | |
| 33. |
Figure of merit is ________ |
| A. | Ratio of output signal to noise ratio to input signal to noise ratio |
| B. | Ratio of input signal to noise ratio to output signal to noise ratio |
| C. | Ratio of output signal to input signal to a system |
| D. | Ratio of input signal to output signal to a system |
| Answer» B. Ratio of input signal to noise ratio to output signal to noise ratio | |
| 34. |
A heterodyne frequency changer is ________ |
| A. | Mixer |
| B. | Demodulator |
| C. | Modulator |
| D. | Local Oscillator |
| Answer» B. Demodulator | |
| 35. |
Superheterodyne principle provides selectivity at ________ |
| A. | RF stage |
| B. | IF stage |
| C. | Demodulating Stage |
| D. | Audio Stage |
| Answer» C. Demodulating Stage | |