MCQOPTIONS
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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.
| 9051. |
Which type of modulator amplifier is used in AM transmitter? |
| A. | Class A |
| B. | Class B |
| C. | Classes AB |
| D. | Class C with negative feedback |
| Answer» E. | |
| 9052. |
A frequency multiplier stage should operate as |
| A. | class A |
| B. | class B |
| C. | class AB |
| D. | class C |
| Answer» C. class AB | |
| 9053. |
The frequency deviation of a FM signal produced from PM is |
| A. | identical to that of FM signal produced by direct method |
| B. | larger than that of a FM signal produced by direct method |
| C. | directly proportional to the peak amplitude and the frequency of modulating signal |
| D. | directly proportional to the peak amplitude of the modulating signal |
| Answer» E. | |
| 9054. |
Good frequency stability can be available |
| A. | crystal oscillators |
| B. | Hartley oscillators |
| C. | colpitts oscillators |
| D. | none of the above |
| Answer» B. Hartley oscillators | |
| 9055. |
A bit synchronizer regenerates at the receiver a clock waveform which is |
| A. | synchronous with original clock waveform |
| B. | out of phase by 180 with original clock waveform |
| C. | out of phase by 90 with the original clock waveform |
| D. | none of the above |
| Answer» B. out of phase by 180 with original clock waveform | |
| 9056. |
Probability of error in DPSK is less than PSK |
| A. | true |
| B. | false |
| C. | equal |
| D. | depend upon noise |
| Answer» B. false | |
| 9057. |
Zero mean Gaussian noise of variance N is applied to a half wave rectifier. The mean squared value of the rectified output will be |
| A. | 0 |
| B. | N/2 |
| C. | N/ |
| D. | <span class="root">2</span> |
| E. | N |
| Answer» C. N/ | |
| 9058. |
In radar display system PPI stands for |
| A. | Pulse Position Indicator |
| B. | Plan Position Indicator |
| C. | Phase Position Indicator |
| D. | Point Position Indicator |
| Answer» C. Phase Position Indicator | |
| 9059. |
A plot of modulation index vs carrier amplitude yields a |
| A. | horizontal line |
| B. | vertical line |
| C. | parabola |
| D. | hyperbola |
| Answer» E. | |
| 9060. |
Electronic tubes used for transmitter differ from their counterparts in the receivers in respect that |
| A. | they are large in size |
| B. | they are capable of handling large powers |
| C. | they generate large amount of heat when in operation |
| D. | none of the above |
| Answer» E. | |
| 9061. |
Consider the following types of distortions in diode detectors Distortion is caused due to the reason that dc and ac load impedances are unequalDistortion is caused because ac load impedance has a reactive component at high audio frequenciesAudio frequency diode current is less than dc current Which of the above are true? |
| A. | 1, 2 and 3 |
| B. | 1 and 2 |
| C. | 1 and 3 |
| D. | 2 and 3 |
| Answer» C. 1 and 3 | |
| 9062. |
In a phase discriminator fc, is the IF to which primary circuit is tuned. Consider the following statements: The primary and secondary voltages are exactly 90 out of phase when input frequency is fcmore than 90 out of phase when input frequency is higher than fcless than 90 out of phase when input frequency is lower than fc Which of the above statements is correct? |
| A. | 1 only |
| B. | 1 and 2 |
| C. | 1, 2 and 3 |
| D. | 2 and 3 |
| Answer» B. 1 and 2 | |
| 9063. |
Satellites used for international communication are called |
| A. | cossort |
| B. | domsat |
| C. | marisat |
| D. | intelsat |
| Answer» E. | |
| 9064. |
The modulation index of an AM wave is changed from 0 to 1. The transmitted power is |
| A. | unchanged |
| B. | halved |
| C. | increased by 50% |
| D. | quadrupled |
| Answer» D. quadrupled | |
| 9065. |
In a radio receiver the input from local oscillator is fed to |
| A. | RF amplifier |
| B. | mixer |
| C. | IF amplifier |
| D. | detector |
| Answer» C. IF amplifier | |
| 9066. |
Which one of the following is digital? |
| A. | Pulse code modulation |
| B. | Pulse width modulation |
| C. | Pulse frequency modulation |
| D. | Pulse position modulation |
| Answer» B. Pulse width modulation | |
| 9067. |
A shadow zone does not receive any space wave |
| A. | True |
| B. | False |
| Answer» B. False | |
| 9068. |
In frequency modulation noise can be further reduced by |
| A. | increasing deviation |
| B. | reducing deviation |
| C. | reducing carrier frequency |
| D. | increasing signal amplitude |
| Answer» B. reducing deviation | |
| 9069. |
Pick the odd one out |
| A. | PPM |
| B. | PDM |
| C. | PWM |
| D. | PLM |
| Answer» B. PDM | |
| 9070. |
In a colour TV receiver SAW filter consists of |
| A. | piezoelectric substrate on which are deposited two inter, digital transducers |
| B. | photo conductive substrate which are deposited two inter digital transducers |
| C. | photo voltaic substrate which are deposited two inter digital transducers |
| D. | photo resistive substrate which are deposited two inter digital transducers |
| Answer» B. photo conductive substrate which are deposited two inter digital transducers | |
| 9071. |
Automatic sensitivity control by target voltage control is easily possible in |
| A. | Vidicon |
| B. | Plumbicon |
| C. | New vicon |
| D. | both (b) and (c) |
| Answer» B. Plumbicon | |
| 9072. |
The start of modern computer age was started by the event |
| A. | development of disc drive |
| B. | development of transistor |
| C. | development of Hollerith code |
| D. | design of EVIAC computer |
| Answer» C. development of Hollerith code | |
| 9073. |
Which of the following is not correct? |
| A. | In SSB amplitude modulated system, the transmitter circuit has to be more stable leading to better reception |
| B. | In SSB amplitude modulated system more channel space is available as compared to double sideband amplitude modulated system |
| C. | In SSB amplitude modulated system the signal is more noise resistant as compared to double sideband system |
| D. | An SSB-AM system requires lesser power (for the same signal strength) as compared to DSB-AM system |
| Answer» B. In SSB amplitude modulated system more channel space is available as compared to double sideband amplitude modulated system | |
| 9074. |
Assertion (A): Data communication using digital data must be very accurate.Reason (R): In analog signals redundancy is available but in digital signals redundancy is not available. |
| 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» B. Both A and R are correct but R is not correct explanation of A | |
| 9075. |
To couple a coaxial line to a parallel line wire it is best to use |
| A. | slotted line |
| B. | balun |
| C. | directional coupler |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/506-239-1.png"> |
| E. | transformer |
| Answer» C. directional coupler | |
| 9076. |
The total bandwidth needed for an AM signal at 55.25 MHz with 0.5 MHz video modulation is |
| A. | 0.25 MHz |
| B. | 0.5 MHz |
| C. | 1 MHz |
| D. | 10 MHz |
| Answer» D. 10 MHz | |
| 9077. |
The bandwidth required for amplitude modulation is |
| A. | half the frequency of modulating signal |
| B. | equal to the frequency of modulating signal |
| C. | twice the frequency of modulating signal |
| D. | four times the frequency of modulating signal |
| Answer» D. four times the frequency of modulating signal | |
| 9078. |
At night D layer of ionosphere is absent. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 9079. |
Diffraction of EM waves |
| A. | arises only with spherical wave front |
| B. | may occur around the edge of an obstacle |
| C. | occurs when waves pass through a big slot |
| D. | none of the above |
| Answer» D. none of the above | |
| 9080. |
Colour picture tube needs higher anode voltage and needs larger beam and cathode currents than monochrome tube because |
| A. | it is bigger in size |
| B. | it has higher level of illumination |
| C. | the tube has to illuminate three phosphors simultaneously |
| D. | the tube has lower efficiency because of aperture mask |
| Answer» E. | |
| 9081. |
In PM, without any modulation, all the transmitted pulses have the same |
| A. | amplitude |
| B. | width |
| C. | amplitude and spacing |
| D. | amplitude, spacing and width |
| Answer» E. | |
| 9082. |
The unit of loudness is |
| A. | phon |
| B. | sone |
| C. | decibel |
| D. | mel |
| Answer» D. mel | |
| 9083. |
In push button type telephone set, pressing a button generates |
| A. | one frequency |
| B. | two high frequencies |
| C. | two low frequencies |
| D. | one low frequency and one high frequency |
| Answer» E. | |
| 9084. |
If sound wave has an intensity of 10 Pa. The dB level is about |
| A. | 1.139 dB |
| B. | 11.39 dB |
| C. | 113.9 dB |
| D. | 1139 dB |
| Answer» D. 1139 dB | |
| 9085. |
The intermediate frequencies in VCR are |
| A. | video 38.9 MHz and audio 33.4 MHz |
| B. | 38.9 MHz for both video and audio |
| C. | 33.4 MHz for both video and audio |
| D. | 33.4 MHz for video and 38.9 MHz for audio |
| Answer» B. 38.9 MHz for both video and audio | |
| 9086. |
Assertion (A): In TV scanning is done from left to right and top to bottom. Reason (R): Interlaced scanning is useful in eliminating flicker |
| 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 | |
| 9087. |
The seven segment display used in watches and clocks generally uses |
| A. | LED |
| B. | LCD |
| C. | Photodiode |
| D. | FET |
| Answer» B. LCD | |
| 9088. |
When a signal is quantized such that the step size S is small in comparison with the peak to peak range of the signal, the mean square quantization error is equal to |
| A. | S |
| B. | <sup>2</sup> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/515-437-1.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/515-437-2.png"> |
| E. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/515-437-3.png"> |
| Answer» E. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/515-437-3.png"> | |
| 9089. |
If e = 10 sin(108 t + 3 sin 104 t) then modulating frequency is |
| A. | 159 Hz |
| B. | 1590 Hz |
| C. | 1.59 MHz |
| D. | 15.9 MHz |
| Answer» C. 1.59 MHz | |
| 9090. |
Assertion (A): Many times a radar cannot detect 'grounding hopping' military aircraft.Reason (R): Ground interference limits the range of radar. |
| 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 | |
| 9091. |
Entropies associated with an extremely unlikely message and that with an extremely likely message are respectively |
| A. | 0 and 0 |
| B. | 1 and 1 |
| C. | 1 and 0 |
| D. | 0 and 1 |
| Answer» B. 1 and 1 | |
| 9092. |
Frequency shifting keying is basically a method involving |
| A. | amplitude modulation |
| B. | frequency modulation |
| C. | phase modulation |
| D. | none of the above |
| Answer» C. phase modulation | |
| 9093. |
Which of the following codes provides parity checks? |
| A. | CCITT-2 |
| B. | EBCDIC |
| C. | ASCII |
| D. | Baudot |
| Answer» D. Baudot | |
| 9094. |
A signal having uniformly distributed amplitude in the interval (- V to + V) is to be encoded using PCM with uniform quantization. The signal to quantization noise ratio is determined by |
| A. | dynamic range of signal |
| B. | sampling rate |
| C. | number of quantizing levels |
| D. | power spectrum of signal |
| Answer» C. number of quantizing levels | |
| 9095. |
Bipolar signalling uses the following bits |
| A. | -1, +1 |
| B. | -1, 0, +1 |
| C. | 0, 1 |
| D. | -1, 0 |
| Answer» C. 0, 1 | |
| 9096. |
The first geostationary satellite was named |
| A. | Intelsat I |
| B. | Intelsat II |
| C. | Intelsat III |
| D. | Early bird |
| Answer» E. | |
| 9097. |
In a colour TV receiver, which of the following incorporates colour saturation control? |
| A. | Chroma detector |
| B. | Colour killer circuit |
| C. | SAW filter |
| D. | Chroma amplifier |
| Answer» E. | |
| 9098. |
Which of the following oscillator is not in FM? |
| A. | Crystal oscillator |
| B. | Hartley oscillator |
| C. | Colpitts oscillator |
| D. | All of the above |
| Answer» C. Colpitts oscillator | |
| 9099. |
The number of spectral component of impulse wave is |
| A. | 1 |
| B. | 0 |
| C. | 2 |
| D. | |
| Answer» E. | |
| 9100. |
Assertion (A): If a carrier is modulated by three sine waves and m1, m2, m3 are the modulation indices, the total modulation index mt is mt = (m12 + m22 + m32)0.5Reason (R): An AM, higher the level of modulation, lower is the audio power required to produce modulation. |
| 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» D. A is wrong but R is correct | |