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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. |
A digital watch contains |
| A. | quartz crystal oscillator |
| B. | RC oscillator |
| C. | LC oscillator |
| D. | either quartz or RC oscillator |
| Answer» B. RC oscillator | |
| 9052. |
The satellites used for intercontinental communication are called |
| A. | Comsat |
| B. | Domsat |
| C. | Marisat |
| D. | Intelsat |
| Answer» E. | |
| 9053. |
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. | |
| 9054. |
A frequency multiplier stage should operate as |
| A. | class A |
| B. | class B |
| C. | class AB |
| D. | class C |
| Answer» C. class AB | |
| 9055. |
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. | |
| 9056. |
Good frequency stability can be available |
| A. | crystal oscillators |
| B. | Hartley oscillators |
| C. | colpitts oscillators |
| D. | none of the above |
| Answer» B. Hartley oscillators | |
| 9057. |
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 | |
| 9058. |
Probability of error in DPSK is less than PSK |
| A. | true |
| B. | false |
| C. | equal |
| D. | depend upon noise |
| Answer» B. false | |
| 9059. |
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/ | |
| 9060. |
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 | |
| 9061. |
A plot of modulation index vs carrier amplitude yields a |
| A. | horizontal line |
| B. | vertical line |
| C. | parabola |
| D. | hyperbola |
| Answer» E. | |
| 9062. |
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. | |
| 9063. |
Consider the following types of distortions in diode detectors
|
| A. | 1, 2 and 3 |
| B. | 1 and 2 |
| C. | 1 and 3 |
| D. | 2 and 3 |
| Answer» C. 1 and 3 | |
| 9064. |
In a phase discriminator fc, is the IF to which primary circuit is tuned. Consider the following statements: The primary and secondary voltages are
|
| A. | 1 only |
| B. | 1 and 2 |
| C. | 1, 2 and 3 |
| D. | 2 and 3 |
| Answer» B. 1 and 2 | |
| 9065. |
Satellites used for international communication are called |
| A. | cossort |
| B. | domsat |
| C. | marisat |
| D. | intelsat |
| Answer» E. | |
| 9066. |
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 | |
| 9067. |
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 | |
| 9068. |
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 | |
| 9069. |
A shadow zone does not receive any space wave |
| A. | True |
| B. | False |
| Answer» B. False | |
| 9070. |
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 | |
| 9071. |
Pick the odd one out |
| A. | PPM |
| B. | PDM |
| C. | PWM |
| D. | PLM |
| Answer» B. PDM | |
| 9072. |
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 | |
| 9073. |
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 | |
| 9074. |
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 | |
| 9075. |
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 | |
| 9076. |
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 | |
| 9077. |
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 | |
| 9078. |
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 | |
| 9079. |
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 | |
| 9080. |
At night D layer of ionosphere is absent. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 9081. |
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 | |
| 9082. |
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. | |
| 9083. |
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. | |
| 9084. |
The unit of loudness is |
| A. | phon |
| B. | sone |
| C. | decibel |
| D. | mel |
| Answer» D. mel | |
| 9085. |
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. | |
| 9086. |
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 | |
| 9087. |
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 | |
| 9088. |
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 | |
| 9089. |
The seven segment display used in watches and clocks generally uses |
| A. | LED |
| B. | LCD |
| C. | Photodiode |
| D. | FET |
| Answer» B. LCD | |
| 9090. |
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"> | |
| 9091. |
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 | |
| 9092. |
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 | |
| 9093. |
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 | |
| 9094. |
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 | |
| 9095. |
Which of the following codes provides parity checks? |
| A. | CCITT-2 |
| B. | EBCDIC |
| C. | ASCII |
| D. | Baudot |
| Answer» D. Baudot | |
| 9096. |
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 | |
| 9097. |
Bipolar signalling uses the following bits |
| A. | -1, +1 |
| B. | -1, 0, +1 |
| C. | 0, 1 |
| D. | -1, 0 |
| Answer» C. 0, 1 | |
| 9098. |
The first geostationary satellite was named |
| A. | Intelsat I |
| B. | Intelsat II |
| C. | Intelsat III |
| D. | Early bird |
| Answer» E. | |
| 9099. |
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. | |
| 9100. |
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 | |