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MCQOPTIONS
This section includes 1362 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 301. |
In phase modulation, the phase deviation is |
| A. | proportional to the amplitude of the signal and varies with frequency |
| B. | remains constant while amplitude and frequency of signal varies |
| C. | proportional to the amplitude of the signal and independent of the frequency |
| D. | none of the above |
| Answer» D. none of the above | |
| 302. |
Which gives minimum probability of error? |
| A. | ASK |
| B. | FSK |
| C. | PSK |
| D. | DPSK |
| Answer» D. DPSK | |
| 303. |
Kell factor is about |
| A. | 5 |
| B. | 3 |
| C. | 0.7 |
| D. | 0.2 |
| Answer» D. 0.2 | |
| 304. |
The audio frequency range is |
| A. | 5 Hz to 1 kHz |
| B. | 50 Hz to 20 kHz |
| C. | 16 Hz to 20 kHz |
| D. | 0 Hz to 20 kHz |
| Answer» D. 0 Hz to 20 kHz | |
| 305. |
Which of the following is present in both TRF receiver and superheterodyne receiver? |
| A. | Detector |
| B. | Mixer |
| C. | IF amplifier |
| D. | Local oscillator |
| Answer» B. Mixer | |
| 306. |
The output of a battery eliminator is about |
| A. | 110 V DC |
| B. | 110 V AC |
| C. | 45 V DC |
| D. | 6 V DC |
| Answer» E. | |
| 307. |
In commercial FM Broadcasting, A radio station transmitting the signal at 98.3 MHz, it is |
| A. | carrier frequency |
| B. | modulation frequency |
| C. | message frequency |
| D. | channel frequency |
| Answer» B. modulation frequency | |
| 308. |
In home tape recorders the tape width is 2 inches. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 309. |
For the transmission of normal speech, the PCM channel needs a bandwidth of __________ kHz. |
| A. | 2 |
| B. | 4 |
| C. | 16 |
| D. | 32 |
| Answer» C. 16 | |
| 310. |
A superheterodyne receiver is to operate in the frequency range 550 kHz - 1650 kHz, with the intermediate frequency of 450 kHz. Let denote the required capacitance ratio of the local oscillator and I denote the image frequency (in kHz) of the incoming signal. If the receiver is tuned to 700 kHz, then |
| A. | R = 4.41 J =1600 |
| B. | R = 2.10 J =1150 |
| C. | R = 3.0 J =1600 |
| D. | R = 9.0 J =1150 |
| Answer» B. R = 2.10 J =1150 | |
| 311. |
In delta modulation, the output signal to quantization noise ratio S0/Nq is (N is the number of bits) |
| A. | N2 |
| B. | N3 |
| C. | N2 |
| D. | N3 |
| Answer» C. N2 | |
| 312. |
The received signal frequency at any time of a super-heterodyne receiver having IF = 456 kHz is 1 MHz. The corresponding image signal is |
| A. | within the medium band |
| B. | outside the medium band |
| C. | depend upon modulation index |
| D. | depends on Modulating frequency |
| Answer» B. outside the medium band | |
| 313. |
The power rating of radio transmitters is around |
| A. | 100 mW |
| B. | 10 W |
| C. | 10 kW |
| D. | 10 MW |
| Answer» D. 10 MW | |
| 314. |
A TV receiver is 40 cm wide and 30 cm high. The EHT supply required is about |
| A. | 2kV |
| B. | 20 kV |
| C. | 53 kV |
| D. | 10 W |
| Answer» C. 53 kV | |
| 315. |
In shot noise |
| A. | the current rises around mean value |
| B. | the current rises to peak value, decreases to zero and then again rises |
| C. | the current may become negative |
| D. | the current is always less than the mean value |
| Answer» E. | |
| 316. |
It is desired to couple a coaxial line to a two parallel wire line. It is best to use |
| A. | quarter wave transformer |
| B. | balun |
| C. | slotted line |
| D. | directional coupler |
| Answer» C. slotted line | |
| 317. |
Consider the following statements about Yagi Uda antenna It is unidirectionalIts gain is about 7 dBIt is used at VLFThe optimum separation is 0.11 Which of the above are correct? |
| A. | 1, 2, 3, 4 |
| B. | 1 and 4 only |
| C. | 10 |
| D. | 1.09 |
| Answer» C. 10 | |
| 318. |
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 | |
| 319. |
A signal is sampled at 8 kHz and is quantized using 8 bit uniform quantizer. Assuming SNRq for a sinusoidal signal, the correct statement for PCM signal with a bit rate of R is |
| A. | R = 32 KbPs, SNRq = 25.8 dB |
| B. | R = 64 KbPs, SNRq = 49.8 dB |
| C. | R = 64 KbPs, SNRq = 58.8 dB |
| D. | R = 32 KbPs, SNRq = 49.8 dB |
| Answer» C. R = 64 KbPs, SNRq = 58.8 dB | |
| 320. |
SSB-SC stands for |
| A. | Single Side Band-Suppressed Carrier |
| B. | Single Side Band-Synchronous Carrier |
| C. | Synchronous Side Band-Suppressed Carrier |
| D. | Synchronous Side Band-Self Carrier |
| Answer» B. Single Side Band-Synchronous Carrier | |
| 321. |
A longwave AM broadcast transmitter needs |
| A. | very small carrier power |
| B. | very large carrier power |
| C. | small carrier power |
| D. | large carrier power |
| Answer» C. small carrier power | |
| 322. |
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. | |
| 323. |
A source generates three symbols with probabilities 0.25, 0.25, 0.50 at a rate of 3000 symbols per second. Assuming independent generation of symbols, the most efficient source encoder would have average bit rate is as |
| A. | 6000 bits/sec |
| B. | 4500 bits/sec |
| C. | 3000 bits/sec |
| D. | 1500 bits/sec |
| Answer» C. 3000 bits/sec | |
| 324. |
The upper and lower side frequencies for 3 kHz audio modulation with a 27 MHz carrier frequency will be |
| A. | 30 and 24 MHz |
| B. | 27.3 and 26.7 MHz |
| C. | 27.3 and 26.97 MHz |
| D. | 27.3 and 26.97 MHz |
| Answer» C. 27.3 and 26.97 MHz | |
| 325. |
A tweeter should be fed from the input through a |
| A. | low pass filter |
| B. | high pass filter |
| C. | band pass filter |
| D. | band stop filter |
| Answer» C. band pass filter | |
| 326. |
PIL colour picture tube has the main advantage that |
| A. | it is cheap |
| B. | it ensures purity in colour |
| C. | it is self convergent |
| D. | both (a) and (b) |
| Answer» D. both (a) and (b) | |
| 327. |
Assertion (A): SSB transmitter is generally smaller than AM transmitter Reason (R): SSB systems mostly use combined transmitter receiver. |
| 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» E. | |
| 328. |
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 | |
| 329. |
The direction of pick up in a CD is |
| A. | linear from centre towards edge |
| B. | linear from edge to centre |
| C. | nonlinear from centre to edge |
| D. | nonlinear from edge to center |
| Answer» B. linear from edge to centre | |
| 330. |
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 | |
| 331. |
Leak type bias is used in plate modulated class C amplifier to |
| A. | increase the bandwidth |
| B. | prevent over modulation |
| C. | prevent excessive grid current |
| D. | prevent tuned circuit damping |
| Answer» D. prevent tuned circuit damping | |
| 332. |
A mobile telephone has a range of about |
| A. | 50 km |
| B. | 10 km |
| C. | 1 km |
| D. | 0.1 km |
| Answer» B. 10 km | |
| 333. |
Neper is |
| A. | larger than a decibel |
| B. | smaller than decibel |
| C. | equal to 1 decibel |
| D. | none of the above |
| Answer» B. smaller than decibel | |
| 334. |
Computer communication networks have |
| A. | star configuration |
| B. | tree configuration |
| C. | loop/mesh configuration |
| D. | All of the above |
| Answer» E. | |
| 335. |
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» E. | |
| 336. |
Which of the following microphones is the cheapest? |
| A. | Moving coil |
| B. | Condenser |
| C. | Ribbon |
| D. | Carbon |
| Answer» E. | |
| 337. |
Sparking affects amplitude modulation. |
| A. | 1 |
| B. | |
| C. | PZT ceramics |
| D. | ZnO |
| Answer» B. | |
| 338. |
The mobile unit of a mobile telephone is generally in |
| A. | vehicles |
| B. | |
| C. | office |
| D. | vehicle or pocket |
| Answer» B. pocket | |
| 339. |
A 400 W carrier is amplitude modulated with m = 0.75. If single side band suppressed carrier is used the total power in modulated wave is |
| A. | 400 W |
| B. | 512 W |
| C. | 112 W |
| D. | 56 W |
| Answer» E. | |
| 340. |
Assertion (A): In angle modulation the transmitted amplitude is constant.Reason (R): Angle modulation has good immunity to noise and interference. |
| 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 | |
| 341. |
A single tone modulating signal Vm cos ωt modulates a carrier A cos ωct. The carrier power (modulated) and side band powers are respectively |
| A. | |
| B. | |
| Answer» B. | |
| 342. |
A signal m(t) with bandwidth 500 Hz is first multiplied by a signal g(t) where . The resulting signal is then passes through an ideal low pass filter with bandwidth 1 kHz the output of the low pass filter would be |
| A. | δ(t) |
| B. | m(t) |
| C. | 0 |
| D. | m(t) δ(t) |
| Answer» C. 0 | |
| 343. |
A radio frequency signal contains the following three frequencies : 850 kHz; 865 kHz and 875 kHz In order to amplify this signal, which of the following amplifier should be selected? |
| A. | Audio frequency amplifier |
| B. | Tuned voltage amplifier |
| C. | PDM |
| D. | PPM |
| Answer» E. | |
| 344. |
What is the frequency of audio modulation? |
| A. | 1000 Hz |
| B. | 2000 Hz |
| C. | 3000 Hz |
| D. | 2000 kHz |
| Answer» C. 3000 Hz | |
| 345. |
Indicate the false statement: To combat noise |
| A. | reduce signalling rate |
| B. | increase transmitted power |
| C. | use redundancy |
| D. | increase channel bandwidth |
| Answer» E. | |
| 346. |
The maximum number of AM broadcast stations that can be accommodated in a 100 kHz bandwidth for the highest modulating frequency of 5 kHz will be |
| A. | 100 |
| B. | 20 |
| C. | 10 |
| D. | 1 |
| Answer» D. 1 | |
| 347. |
The first pulse in a TV remote control is |
| A. | either start pulse or preliminary pulse |
| B. | erase pulse |
| C. | poor AGC operation |
| D. | poor AF response |
| Answer» C. poor AGC operation | |
| 348. |
A circuit which cannot demodulate SSB is |
| A. | balanced modulator |
| B. | product detector |
| C. | BFO |
| D. | phase discriminator |
| Answer» E. | |
| 349. |
A computer monitor uses 180 W in normal operation and 20 W in sleep mode. The computer is on all the 24 hours but is in sleep mode for 18 hours a days. The energy units saved in 30 days are |
| A. | 0.54 units |
| B. | 86.4 units |
| C. | 2.88 units |
| D. | 4.8 units |
| Answer» C. 2.88 units | |
| 350. |
If luminance signal Y = 0.3 R + 0.59 G + 0.11 B, the hue of R - Y colour is |
| A. | 0.7 R - 0.59 G - 0.11 B |
| B. | - 0.7 R + 0.59 G + 0.11 B |
| C. | 1.3 R - 0.59 G - 0.11 B |
| D. | none of the above |
| Answer» B. - 0.7 R + 0.59 G + 0.11 B | |