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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.
| 8301. |
In SSB generation, the most commonly used filter is |
| A. | low pass |
| B. | RC |
| C. | LC |
| D. | mechanical |
| Answer» E. | |
| 8302. |
The FM broadcast band is from |
| A. | 550 to 1600 kHz |
| B. | 88 to 108 kHz |
| C. | 88 to 108 MHz |
| D. | 1600 kHz to 59.75 MHz |
| Answer» D. 1600 kHz to 59.75 MHz | |
| 8303. |
If a source of information generates messages at the rate of r messages per second and H is entropy, the information rate is |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/516-467-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/516-467-2.png"> |
| C. | <i>r</i> |
| D. | H |
| E. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/516-467-3.png"> |
| Answer» D. H | |
| 8304. |
Multiplex techniques are used for |
| A. | low density communications |
| B. | low density point-to-point communications |
| C. | high-density point-to-point communications |
| D. | all of the above |
| Answer» D. all of the above | |
| 8305. |
An FM transmitter has maximum frequency deviation of 75 kHz and reproduces audio signals up to 15 kHz. Minimum channel width required is __________ kHz. |
| A. | 180 |
| B. | 120 |
| C. | 90 |
| D. | 60 |
| Answer» C. 90 | |
| 8306. |
In a hi-fi system the frequency response over the audio frequency range should be within |
| A. | 10 dB |
| B. | 5 dB |
| C. | 2 dB |
| D. | 1 dB |
| Answer» E. | |
| 8307. |
A 360 W carrier is simultaneously modulated by two audio wave with modulation percentage of 55 and 65 respectively. Total sideband power radiated will be |
| A. | 500 W |
| B. | 360 W |
| C. | 180 W |
| D. | 130 W |
| Answer» E. | |
| 8308. |
Under identical conditions, for a single modulating frequency, FM and PM are indistinguishable. Now if the modulating frequency is reduced, then |
| A. | phase modulation index as well as frequency modulation index decrease |
| B. | phase modulation index as well as frequency modulation index increase |
| C. | phase modulation index will remain constant whereas frequency modulation index will increase |
| D. | phase modulation index will decrease whereas frequency modulation index will remain constant |
| Answer» D. phase modulation index will decrease whereas frequency modulation index will remain constant | |
| 8309. |
In a radio detector |
| A. | stabilization against signal strength variation is provided |
| B. | linearity is worse than in a phase discriminator |
| C. | the circuit is the same as in discriminator except that diodes are reversed |
| D. | output is twice that obtainable from a similar phase discriminator |
| Answer» C. the circuit is the same as in discriminator except that diodes are reversed | |
| 8310. |
ISDN stands for |
| A. | Integrated Services Digital Network |
| B. | Inter Services Digital Network |
| C. | Inter Subscriber Digital Network |
| D. | integrated Subscriber Digital Network |
| Answer» B. Inter Services Digital Network | |
| 8311. |
Consider the following statements as regards noise If Gaussian noise is applied at input of a rectifier, the output is not gaussianThe noise encountered on a telephone line consists of short, pulse type disturbances whose amplitude distribution is not GaussianShot noise results from random emission of electrons from a cathodeShot noise results from phenomenon associated with the flow of current across semi conductor junctions Which of the above are correct? |
| A. | 1, 2, 3, only |
| B. | 1, 2, 4 only |
| C. | 1, 2, 3, 4 |
| D. | 2, 3 only |
| Answer» D. 2, 3 only | |
| 8312. |
The main advantage of superheterodyne receiver is |
| A. | better tracking |
| B. | simple cut |
| C. | better alignment |
| D. | improvement in selectivity and sensitivity |
| Answer» E. | |
| 8313. |
PAL system was proposed first in |
| A. | USA |
| B. | Japan |
| C. | England |
| D. | Germany |
| Answer» E. | |
| 8314. |
MCVF telegraphy causes |
| A. | SSB techniques |
| B. | pulse modulation |
| C. | Out of bond signalling |
| D. | FM |
| Answer» B. pulse modulation | |
| 8315. |
Noise can be reduced by increasing sampling rate |
| A. | true |
| B. | false |
| C. | can't say |
| D. | insufficient data |
| Answer» C. can't say | |
| 8316. |
Which of the following pulse communication system is inherently immune to noise? |
| A. | PPM |
| B. | PCM |
| C. | PWM |
| D. | PAM |
| Answer» C. PWM | |
| 8317. |
In a PCM system, if we increase the quantization levels from 2 to 8, how do the relative bandwidth requirements vary? |
| A. | Get doubled |
| B. | Get tripled |
| C. | Remains same |
| D. | Become eight times |
| Answer» C. Remains same | |
| 8318. |
If the target area is small compared to wavelength of radar the situation is called |
| A. | resonance region |
| B. | Rayleigh region |
| C. | optical region |
| D. | binomial region |
| Answer» C. optical region | |
| 8319. |
In a Vidicon camera tube, |
| A. | both sides of the target plate have the coating of tin oxide |
| B. | both sides of the target plate have the coating of antimony tri-sulphide |
| C. | the side of target plate facing the light has a coating of tin oxide and the side facing electron gun has a coating of antimony trisulphide |
| D. | the side of target plate facing the light has a coating of antimony trisulphide while the side facing the electron gun has a coating of tin oxide |
| Answer» D. the side of target plate facing the light has a coating of antimony trisulphide while the side facing the electron gun has a coating of tin oxide | |
| 8320. |
The distance at which a sky wave is received back on earth decreases with angle of incidence for all angles of incidence. |
| A. | True |
| B. | False |
| Answer» C. | |
| 8321. |
A trigonometric function is synonyms to |
| A. | orthogonal function |
| B. | triangular function |
| C. | singular function |
| D. | none of the above |
| Answer» C. singular function | |
| 8322. |
A single tone modulating signal Vm cos t modulates a carrier A cos ct. The carrier power (modulated) and side band powers are respectively |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/498-38-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/498-38-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/498-38-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/498-38-4.png"> |
| Answer» B. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/498-38-2.png"> | |
| 8323. |
The autocorrelation function of the white noise is |
| A. | impulse function |
| B. | step function |
| C. | constant |
| D. | none of the above |
| Answer» D. none of the above | |
| 8324. |
An image uses 512 x 512 picture elements. Each element can take any of eight distinguishable levels. The maximum entropy in the above image will be |
| A. | 2097152 bits |
| B. | 786432 bits |
| C. | 648 bits |
| D. | 144 bits |
| Answer» C. 648 bits | |
| 8325. |
The subcarrier frequency for transmission of colour difference signals in TV systems in India is |
| A. | 9.47 MHz |
| B. | 4.43 MHz |
| C. | 2.06 MHZ |
| D. | 1.3 MHz |
| Answer» E. | |
| 8326. |
A helical antenna is used for satellite tracking due to its |
| A. | good front to back ratio |
| B. | broad bandwidth |
| C. | circular polarization |
| D. | both (a) and (b) |
| Answer» B. broad bandwidth | |
| 8327. |
In a FM signal, the modulation index increases, then the power |
| A. | increases |
| B. | decreases |
| C. | remains constant |
| D. | none of the above |
| Answer» D. none of the above | |
| 8328. |
Higher order TDM levels are obtained by |
| A. | forming super master groups |
| B. | using A law |
| C. | using law |
| D. | dividing pulse width |
| Answer» E. | |
| 8329. |
Assertion (A): In AM, use of SSB reduces the power and bandwidth requirementReason (R): A balanced modulator produces AM with carrier suppressed |
| 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 | |
| 8330. |
Limiter is not essential in the following detector |
| A. | foster-Seeley |
| B. | ratio detector |
| C. | balanced |
| D. | none of the above |
| Answer» C. balanced | |
| 8331. |
The phase of colour subcarrier burst in PAL is along the axis at |
| A. | +180 |
| B. | -180 |
| C. | 180 |
| D. | 45 |
| Answer» D. 45 | |
| 8332. |
Chrome signals in PAL colour television system consist of |
| A. | R - Y and B - Y signal |
| B. | V and U signals |
| C. | I and Q signals |
| D. | R - Y and G - Y signals |
| Answer» C. I and Q signals | |
| 8333. |
In TV system in India, each frame is divided into |
| A. | 625 horizontal lines |
| B. | 525 horizontal lines |
| C. | 425 horizontal lines |
| D. | 325 horizontal lines |
| Answer» B. 525 horizontal lines | |
| 8334. |
Among the various modulation systems, the most favoured from the point of linearity of modulation and efficiency is |
| A. | anode or collector modulation |
| B. | central grid modulation |
| C. | screen grid modulation |
| D. | modulated oscillators |
| Answer» B. central grid modulation | |
| 8335. |
In PAL system |
| A. | phase of U signal is reversed on alternating lines |
| B. | phase of V signal is reversed on alternating lines |
| C. | phases of both U and V signals are reversed on alternating lines |
| D. | none of the above |
| Answer» C. phases of both U and V signals are reversed on alternating lines | |
| 8336. |
A receiver has poor selectivity. It will also have poor |
| A. | sensitivity |
| B. | double spotting |
| C. | blocking |
| D. | diversity reception |
| Answer» D. diversity reception | |
| 8337. |
Ground wave can be used for communication upto |
| A. | 5 kHz |
| B. | 12 kHz |
| C. | 16 kHz |
| D. | 25 kHz |
| Answer» D. 25 kHz | |
| 8338. |
A Marconi antenna |
| A. | is a grounded antenna with a length equal to /4 |
| B. | is an ungrounded antenna with a length equal to /4 |
| C. | has a length equal to 1 |
| D. | has a length equal to /2 |
| Answer» B. is an ungrounded antenna with a length equal to /4 | |
| 8339. |
When large amount of power is required, a push pull amplifier is designed for operation as |
| A. | class A |
| B. | class B |
| C. | class C |
| D. | class AB |
| Answer» C. class C | |
| 8340. |
Which of the following is the main advantage of PCM system? |
| A. | Lower noise |
| B. | Lower power |
| C. | Lower bandwidth |
| D. | All of the above |
| Answer» B. Lower power | |
| 8341. |
BPSK stands for |
| A. | Binary Phase Shifting Key |
| B. | Broad Phase Shifting Key |
| C. | Bit Phase Shifting Key |
| D. | Binary Pulse Shifting Key |
| Answer» B. Broad Phase Shifting Key | |
| 8342. |
In amplitude modulation the rms value of radio frequency voltage after 40% modulation is 60 mV. If modulation is 80% the rms value after modulation will be about |
| A. | 50 mV |
| B. | 60 mV |
| C. | 66 mV |
| D. | 80 mV |
| Answer» D. 80 mV | |
| 8343. |
In the spectrum of an FM wave |
| A. | When modulation index is large, carrier frequency disappears |
| B. | carrier frequency cannot disappear |
| C. | amplitude of any side band depends on modulation index |
| D. | the total number of side bands depend on modulation index |
| Answer» D. the total number of side bands depend on modulation index | |
| 8344. |
Consider the following statements In a pulsed radar, the transmitted pulses are of high frequencyIn a pulsed radar, the transmitted pulses are of high powerIn a pulsed radar, the transmitted pulses are of brief durationIn a pulsed radar, the transmitted pulses are of square wave shape. Of the above statements the correct statements are |
| A. | 1 only |
| B. | 1, 2 and 3 only |
| C. | 1, 2, 3, 4 |
| D. | 1 and 3 only |
| Answer» C. 1, 2, 3, 4 | |
| 8345. |
Probability density function of thermal noise is |
| A. | Poisson |
| B. | Binomial |
| C. | Gaussian |
| D. | None of the above |
| Answer» B. Binomial | |
| 8346. |
In a colour TV receiver AFT stands for |
| A. | Automatic Fine Tuning |
| B. | Automatic Frequency Tuning |
| C. | Automatic Field Tuning |
| D. | Alignment Frequency Tuning |
| Answer» B. Automatic Frequency Tuning | |
| 8347. |
The reactance of bypass capacitor in a CE amplifier circuit should be |
| A. | equal to the resistance in parallel with it |
| B. | equal to 10% or less of the resistance in parallel with it |
| C. | equal to 50% of the resistance in parallel with it |
| D. | independent of the resistance in parallel with it |
| Answer» C. equal to 50% of the resistance in parallel with it | |
| 8348. |
Which of the following microphones has highest output impedance? |
| A. | Carbon |
| B. | Ribbon |
| C. | Crystal |
| D. | Condenser |
| Answer» E. | |
| 8349. |
Consider the following statements about PCM PCM is not noise resistantPCM requires complex encoding and quantizing circuitryPCM requires large bandwidth Which of the above are correct? |
| A. | 1 only |
| B. | 1, 2, 3 |
| C. | 2, 3 |
| D. | 1 and 3 |
| Answer» D. 1 and 3 | |
| 8350. |
In a television transmitter, the output stage is most likely to be |
| A. | screen modulated class C amplifier |
| B. | plate modulated class C amplifier |
| C. | grid modulated class A amplifier |
| D. | grid modulated class C amplifier |
| Answer» E. | |