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MCQOPTIONS
This section includes 9294 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 9101. |
Typical value of power consumption of TV transmitter is |
| A. | 0.5 kVA |
| B. | 2 kVA |
| C. | 50 kVA |
| D. | 1000 kVA |
| Answer» D. 1000 kVA | |
| 9102. |
When a wave reaches the open circuited end of a line |
| A. | all the forward energy is reflected by the open circuit |
| B. | all the forward energy is absorbed by the open circuit |
| C. | a small portion of energy is radiated into atmosphere and the remaining energy is reflected |
| D. | either (a) or (b) |
| Answer» D. either (a) or (b) | |
| 9103. |
The orbital period of a geostationary communication satellite is |
| A. | 12 hours |
| B. | 24 hours |
| C. | 36 hours |
| D. | 48 hours |
| Answer» C. 36 hours | |
| 9104. |
The complete video signal consists of |
| A. | video signal and synchronising pulses |
| B. | video signal, synchronising pulses and blanking pulses |
| C. | video signal corresponding to picture information only |
| D. | video signal and blanking pulses |
| Answer» C. video signal corresponding to picture information only | |
| 9105. |
Which of the following is not true as regards communication receiver? |
| A. | It is exactly same as radio receiver used in households |
| B. | It can be used, besides communication, for detection in high frequency bridges |
| C. | It is designed to perform the task of low and high frequency reception better than in household receiver |
| D. | Its tuning and operation are more complicated than those in household receiver |
| Answer» B. It can be used, besides communication, for detection in high frequency bridges | |
| 9106. |
Which one of the following frequency bands is allocated by ITU (International Telecomm. Union) for DBS - (Direct Broadcast service) also referred as DTH - (Direct to Home service)? |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/538-1015-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/538-1015-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/538-1015-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/538-1015-4.png"> |
| Answer» C. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/538-1015-3.png"> | |
| 9107. |
FM broadcast lies in which band? |
| A. | HF |
| B. | SHF |
| C. | UHF |
| D. | VHF |
| Answer» E. | |
| 9108. |
Which colour picture tube uses slotted aperture mask? |
| A. | Trinitron |
| B. | Shadow mask tube |
| C. | PIL |
| D. | None of the above |
| Answer» D. None of the above | |
| 9109. |
If the circumference of a spherical target is between 1 to 10 wavelength in a radar system, the situation is called |
| A. | resonance region |
| B. | Rayleigh region |
| C. | optical region |
| D. | binomial region |
| Answer» B. Rayleigh region | |
| 9110. |
For TV broadcast, picture signal is modulated in |
| A. | SSB |
| B. | VSB |
| C. | FM |
| D. | AM |
| Answer» E. | |
| 9111. |
Assertion (A): Stubs, directional couplers and baluns are very commonly used in communication systemsReason (R): Characteristic impedance of a line is an important parameter. |
| A. | Both A and R are correct and R is correct explanation of A |
| B. | Both A and R are correct but R is not correct explanation of A |
| C. | A is correct but R is wrong |
| D. | A is wrong but R is correct |
| Answer» C. A is correct but R is wrong | |
| 9112. |
Audio frequency range lies between |
| A. | 20 Hz and 20 kHz |
| B. | 20 kHz and 20 MHz |
| C. | 2 MHz and 20 MHz |
| D. | 20 MHz and 200 MHz |
| Answer» B. 20 kHz and 20 MHz | |
| 9113. |
Assertion (A): SSB and ISB receivers have good S/N ratioReason (R): SSB and ISB receivers have good suppression of adjacent channels. |
| A. | Both A and R are correct and R is correct explanation of A |
| B. | Both A and R are correct but R is not correct explanation of A |
| C. | A is correct but R is wrong |
| D. | A is wrong but R is correct |
| Answer» C. A is correct but R is wrong | |
| 9114. |
De-emphasis circuit is used |
| A. | to attenuate high frequencies |
| B. | to attenuate low frequencies |
| C. | to attenuate mid-band frequencies |
| D. | None of the above |
| Answer» B. to attenuate low frequencies | |
| 9115. |
Some features of RF stage in good radio receivers is It increases sensitivity by providing amplification to RF signalIt eliminates image frequency interferenceIt increases selectivityIt reduces noise level Which of the above are true? |
| A. | 1, 2 and 3 only |
| B. | 1, 2 and 4 only |
| C. | 2, 3, 4 only |
| D. | 1, 2, 3, 4 |
| Answer» E. | |
| 9116. |
During amplitude modulation, the phase angle of the modulating voltage changes by |
| A. | 0 |
| B. | 45 |
| C. | 90 |
| D. | 180 |
| Answer» B. 45 | |
| 9117. |
The image frequency of a superheterodyne receiver is |
| A. | created within the receiver itself |
| B. | not rejected by IF tuned circuits |
| C. | independent of the frequency of tuning |
| D. | due to insufficient adjacent channel rejection |
| Answer» C. independent of the frequency of tuning | |
| 9118. |
Image frequency rejection mainly depends upon |
| A. | detector |
| B. | mixer |
| C. | IF |
| D. | RF |
| Answer» B. mixer | |
| 9119. |
The figure shows a simple detector circuit for amplitude modulated wave v(t) = (1 + m cos mt) cost ct. If the detector is to follow the envelope of modulated wave at all times the extent of modulation m must be less than or equal to m0 where m0 is given by equation |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/514-431-2.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/514-431-3.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/514-431-4.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/514-431-5.png"> |
| Answer» B. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/514-431-3.png"> | |
| 9120. |
Which of the following is most likely to be found in an SSB transmitter? |
| A. | Class A, RF output amplifier |
| B. | Class B, RF amplifier |
| C. | Tuned modulator |
| D. | Class C, audio amplifier |
| Answer» C. Tuned modulator | |
| 9121. |
Which one of the following is correct? |
| A. | Coding reduces the noise in the signal |
| B. | Coding deliberately introduces redundancy into messages |
| C. | Coding increases the information rate |
| D. | Coding increases the channel bandwidth |
| Answer» B. Coding deliberately introduces redundancy into messages | |
| 9122. |
Huffman code is also known as redundancy code |
| A. | True |
| B. | false |
| C. | in some cases |
| D. | depend upon efficiency |
| Answer» B. false | |
| 9123. |
A paraboloid reflector has mouth diameter D meters, wavelength meters. Its beam width is equal to |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/522-609-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/522-609-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/522-609-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/522-609-4.png"> |
| Answer» B. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/522-609-2.png"> | |
| 9124. |
In AM increased depth of modulation increases __________ and in FM with increased depth of modulation __________ increases. |
| A. | total transmitted power, bandwidth |
| B. | bandwidth, bandwidth |
| C. | bandwidth, total transmitted power |
| D. | total transmitted power, sideband power |
| Answer» B. bandwidth, bandwidth | |
| 9125. |
In a DM system, the granular noise occurs when modulating signal |
| A. | decrease Rapidly |
| B. | increase |
| C. | has high frequency component |
| D. | change within step size |
| Answer» D. change within step size | |
| 9126. |
In communication receivers the fidelity is provided by |
| A. | audio stage |
| B. | detector range |
| C. | mixer stage |
| D. | all of the above |
| Answer» B. detector range | |
| 9127. |
Which of the following is true as regards telephone systems? |
| A. | A larger facility carrying a larger load operates less efficiently than a smaller capacity |
| B. | A larger facility carrying a lesser load operates more efficiently than a smaller capacity |
| C. | A larger facility carrying a larger load operates more efficiently than a smaller capacity |
| D. | A smaller capacity carrying a larger load operates more efficiently than a larger capacity |
| Answer» D. A smaller capacity carrying a larger load operates more efficiently than a larger capacity | |
| 9128. |
SSB can be generated by |
| A. | filter method |
| B. | phase shift method |
| C. | weaver's method |
| D. | none of the above |
| Answer» E. | |
| 9129. |
In a television camera tube, scanning of a picture is done |
| A. | line by line from left to right |
| B. | line by line from right to left |
| C. | line by line from top to bottom |
| D. | line by line from bottom to top |
| Answer» B. line by line from right to left | |
| 9130. |
A balanced modulator circuit uses |
| A. | two identical diodes with same V-I characteristics |
| B. | two triodes with different V-I characteristics |
| C. | two diodes with different V-I characteristics |
| D. | a diode and a triode |
| Answer» B. two triodes with different V-I characteristics | |
| 9131. |
Which one of the following cannot be used to remove the unwanted sideband in SSB? |
| A. | Balanced modulator |
| B. | Phase shift method |
| C. | Filter system |
| D. | Third method |
| Answer» B. Phase shift method | |
| 9132. |
For FM, which of the following statement is not true? |
| A. | The bandwidth increases as modulation index is increased |
| B. | The total power remains constant with respect to modulation index |
| C. | The carrier never becomes zero |
| D. | All of the above |
| Answer» D. All of the above | |
| 9133. |
Companding is used in PCM to |
| A. | reduce bandwidth |
| B. | increasing S/N ratio |
| C. | get almost uniform S/N ratio |
| D. | increase bandwidth |
| Answer» D. increase bandwidth | |
| 9134. |
Assertion (A): In AM the amplitude of carrier is made proportional to the instantaneous amplitude of modulating waveReason (R): In AM, frequency of side band = frequency carrier frequency of modulating wave. |
| A. | Both A and R are correct and R is correct explanation of A |
| B. | Both A and R are correct but R is not correct explanation of A |
| C. | A is correct but R is wrong |
| D. | A is wrong but R is correct |
| Answer» C. A is correct but R is wrong | |
| 9135. |
Which of the following is the disadvantage of PDM and PPM? |
| A. | It requires pulses of larger widths |
| B. | More samples are needed per second |
| C. | More powerful transmitter is required |
| D. | None of the above |
| Answer» D. None of the above | |
| 9136. |
Frequency frogging is used in a carrier system to |
| A. | conserve frequencies |
| B. | reduce distortion |
| C. | reduce cross talk |
| D. | none of the above |
| Answer» D. none of the above | |
| 9137. |
Which is most important subsystem for recovering and reconstructing signal in a TDM system? |
| A. | Envelope detector followed by a low pass filter |
| B. | Synchronization ckt for proper timing |
| C. | Bandpass filter to segregate channels |
| D. | Coherent detector to ensure frequency and phase connection |
| Answer» B. Synchronization ckt for proper timing | |
| 9138. |
Which one of the following is an indirect way of generating FM? |
| A. | Armstrong modulator |
| B. | Varactor diode modulator |
| C. | Reactance FET modulator |
| D. | Reactance bipolar transistor modulator |
| Answer» B. Varactor diode modulator | |
| 9139. |
TDM |
| A. | can be used with PCM only |
| B. | interleaves pulses belonging to different transmissions |
| C. | combines five groups into a super group |
| D. | stacks 24 channels in adjacent frequency slots |
| Answer» C. combines five groups into a super group | |
| 9140. |
Pressing a key on telephone set generates two frequencies. The basis for selection of these frequencies is |
| A. | the harmonics of one frequency should not be mistaken for the other frequency |
| B. | the audio input to the handset transmitter should not be mistaken for a key pressing |
| C. | both (a) and (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 9141. |
PA radar means |
| A. | Phased Array radar |
| B. | Pulsed Array radar |
| C. | Pulse Amplitude radar |
| D. | None of the above |
| Answer» B. Pulsed Array radar | |
| 9142. |
Dynamic range of hi-fi system is at least |
| A. | 150 dB |
| B. | 120 dB |
| C. | 80 dB |
| D. | 40 dB |
| Answer» D. 40 dB | |
| 9143. |
A band limited signal is sampled at the Nyquist rate. The signal can be recovered by passing the samples through |
| A. | an RC filter |
| B. | an envelope detector |
| C. | a PPL |
| D. | an ideal low pass filter with the appropriate bandwidth |
| Answer» E. | |
| 9144. |
The number of repeaters in a coaxial cable link depends on |
| A. | system bandwidth |
| B. | separation of equalizers |
| C. | the number of coaxial cables in the tube |
| D. | none of the above |
| Answer» B. separation of equalizers | |
| 9145. |
In binary data transmission DPSK is preferred to PSK because |
| A. | a coherent carrier is not required to the generated at the receiver |
| B. | for a given energy per bit, the probability for zero is less |
| C. | the 180 phase shifts of the carrier |
| D. | more protection is provided against impulse noise |
| Answer» B. for a given energy per bit, the probability for zero is less | |
| 9146. |
A basic group B |
| A. | consists of five super groups |
| B. | has a frequency range of 60 to 108 kHz |
| C. | consists of erect channels only |
| D. | is formed at group translating equipment |
| Answer» C. consists of erect channels only | |
| 9147. |
By the use of which of the following the PPM can be converted to PWM? |
| A. | A stable multivibrator |
| B. | Integrator |
| C. | Monostable multivibrator |
| D. | Bistable Multivibrator |
| Answer» E. | |
| 9148. |
Which of the following pulse-time modulation is least used? |
| A. | PDM |
| B. | PPM |
| C. | PWM |
| D. | PAM |
| Answer» E. | |
| 9149. |
What is the RF amplifier plate voltage when the audio-modulating voltage is +600 V? |
| A. | -600 V |
| B. | Zero |
| C. | 600 V |
| D. | 1200 V |
| Answer» D. 1200 V | |
| 9150. |
FM has |
| A. | two sidebands only |
| B. | four sidebands only |
| C. | eight sidebands only |
| D. | infinite sidebands |
| Answer» E. | |