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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.
| 8401. |
Cross talk is due to reception of portions of a signal from one channel into another. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8402. |
In the above case the total power in the modulated wave double sideband, suppressed carrier AM will be |
| A. | 112 W |
| B. | 400 W |
| C. | 415 W |
| D. | 512 W |
| Answer» C. 415 W | |
| 8403. |
If there are M equally likely and independent messages and M = 2N where N is an integer, the information in each message is equal to |
| A. | N bits |
| B. | 0.5 N bits |
| C. | 2 N bits |
| D. | 4 N bits |
| Answer» B. 0.5 N bits | |
| 8404. |
A radar beacon is a small radar set having a receiver, a separate transmitter and an antenna. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8405. |
In the stabilized reactance modulators AFC system |
| A. | the discriminator must have a fast time constant to prevent demodulation |
| B. | the higher discriminator frequency the better the oscillator frequency stability |
| C. | the discriminator frequency must not be too low, or the system will fail |
| D. | phase modulation is converted into FM by the equalizer circuit |
| Answer» E. | |
| 8406. |
An antenna is 30 metre high. The frequency is 1 MHz. The radiation resistance is about |
| A. | 1500 Ω |
| B. | 150 Ω |
| C. | 15 Ω |
| D. | 1.5 Ω |
| Answer» D. 1.5 Ω | |
| 8407. |
Which of the following codes is based on BCD format? |
| A. | EBCDIC |
| B. | ASCII |
| C. | Hollerith |
| D. | both (a) and (b) |
| Answer» E. | |
| 8408. |
Which of the following terms is not applicable to Yagi-Uda array? |
| A. | High gain |
| B. | Folded dipole |
| C. | Parasitic elements |
| D. | Good bandwidth |
| Answer» B. Folded dipole | |
| 8409. |
If transmission path, in PCM, is very long then |
| A. | repeater stations are used |
| B. | pulse width may be increased |
| C. | pulse amplitude is increased |
| D. | pulse spacing is reduced |
| Answer» B. pulse width may be increased | |
| 8410. |
In a single tone AM the power of carrier is P and modulation index is m. The powers of each of the two side bands are |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/498-46-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/498-46-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/498-46-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/498-46-4.png"> |
| Answer» B. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/498-46-2.png"> | |
| 8411. |
In a TV receiver the raster is normal but there is no sound and quality of picture is poor. The defective part is |
| A. | power supply |
| B. | loudspeaker |
| C. | AGC, video IF amplifier, RF amplifier |
| D. | horizontal oscillator |
| Answer» D. horizontal oscillator | |
| 8412. |
A trinitron colour picture tube uses |
| A. | three electron guns |
| B. | one electron gun |
| C. | one electron gun with three separate in line cathodes |
| D. | none of the above |
| Answer» D. none of the above | |
| 8413. |
For a three stage cascaded amplifier, having gains of G1, G2 and G3 and noise figures of F1, F2, F3 the overall noise figure |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/505-230-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/505-230-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/505-230-3.png"> |
| D. | None of the above |
| Answer» B. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/505-230-2.png"> | |
| 8414. |
In figure (A) and (B) |
| A. | A represents PCM and B represents AM |
| B. | A represents FM and B represents AM |
| C. | A represents AM and B represents FM |
| D. | A represents PCM and B represents FM |
| Answer» D. A represents PCM and B represents FM | |
| 8415. |
A video transmission system transmits 625 picture frames per second. Each frame consist of a 400 x 400 pixel grid with 64 intensity levels per pixel. The data rate of the system is |
| A. | 16 Mbps |
| B. | 100 Mbps |
| C. | 600 Mbps |
| D. | 6.4 Gbps |
| Answer» D. 6.4 Gbps | |
| 8416. |
Which of the following is a false statement about Armstrong modulation system? |
| A. | The system is basically phase, not frequency, modulation |
| B. | AFC is not needed, as a crystal oscillator is used |
| C. | Equalization is unnecessary |
| D. | Frequency multiplication must be used |
| Answer» D. Frequency multiplication must be used | |
| 8417. |
Which one is digital modulation technique? |
| A. | AM |
| B. | PAM |
| C. | PCM |
| D. | None |
| Answer» E. | |
| 8418. |
Reception through space wave is limited to line of sight distance. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8419. |
Since noise phase modulated FM wave, as the noise sideband frequency approaches the carrier frequency, the noise amplitude |
| A. | is equalized |
| B. | is increased |
| C. | is decreased |
| D. | remains constant |
| Answer» D. remains constant | |
| 8420. |
PWM can be generated |
| A. | by a free running multivibrator |
| B. | by integrating the signal |
| C. | by a monostable multivibrator |
| D. | by differentiating pulse position modulation |
| Answer» D. by differentiating pulse position modulation | |
| 8421. |
Baudot code is a six bit code. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8422. |
The inductance of connecting leads can be a source of |
| A. | low frequency parasitics |
| B. | high frequency parasitics |
| C. | carrier frequency parasitics |
| D. | none of the above |
| Answer» C. carrier frequency parasitics | |
| 8423. |
Which of the following cannot be used to demodulate SSB? |
| A. | Complete phase shift generator |
| B. | Product detector |
| C. | Diode balanced modulator |
| D. | Bipolar transistor balanced modulator |
| Answer» E. | |
| 8424. |
The power required to produce a gain of 10 dB over 4 W of original power is __________ watt. |
| A. | 80 |
| B. | 40 |
| C. | 0.4 |
| D. | 8 |
| Answer» D. 8 | |
| 8425. |
Noise figure is defined as |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/512-382-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/512-382-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/512-382-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/512-382-4.png"> |
| Answer» D. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/512-382-4.png"> | |
| 8426. |
For F2 layer the critical frequency is about |
| A. | 500 MHz |
| B. | 100 MHz |
| C. | 25 MHz |
| D. | 10 MHz |
| Answer» E. | |
| 8427. |
In a radar system the solution to blind speed problem is to |
| A. | use MTI |
| B. | use monopoles |
| C. | vary PRF |
| D. | change Doppler frequency |
| Answer» D. change Doppler frequency | |
| 8428. |
For a FM wave carrier modulating frequency is 10 kHz and bandwidth is 2 MHz. If the modulating signal amplitude is doubled, the bandwidth will be |
| A. | 0.5 MHz |
| B. | 1 MHz |
| C. | 2 MHz |
| D. | 4 MHz |
| Answer» E. | |
| 8429. |
In band III of TV, distant reception (beyond line of sight range) is possible due to |
| A. | tropospheric bending by refraction |
| B. | reflection of waves |
| C. | ionospheric scattering |
| D. | none of the above |
| Answer» B. reflection of waves | |
| 8430. |
If a dipole is meant for a frequency of 1 MHz, the length of each rod is about |
| A. | 5 m |
| B. | 20 m |
| C. | 100 m |
| D. | 50 m |
| Answer» E. | |
| 8431. |
Consider the following statements: In a radar system having a high value of the ratio (antenna diameter)/wavelength the maximum range is largegood target discrimination is achievedcapture area is increasedtarget acquisition is difficult Which of the above are correct? |
| A. | 1, 2, 3, 4 |
| B. | 1, 2, 3 |
| C. | 1, 2 |
| D. | 1, 3, 4 |
| Answer» C. 1, 2 | |
| 8432. |
Assertion (A): The maximum range of a radar is proportional to fourth root of the peak transmitted pulse power.Reason (R): Radar signals are subjected twice to inverse square law. |
| 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 | |
| 8433. |
Which of following digital modulation technique? |
| A. | ASK |
| B. | FSK |
| C. | PSK |
| D. | All |
| Answer» E. | |
| 8434. |
A discrete zero memory information source has 40 symbols and each symbol is equally likely. The minimum number of bits required to code the source with uniform length code and entropy of the source are |
| A. | 5 and 5.03 |
| B. | 6 and 5.83 |
| C. | 5 and 6.64 |
| D. | 6 and 5.32 |
| Answer» E. | |
| 8435. |
The standard intermediate frequency for FM ratio is |
| A. | 10.7 MHz |
| B. | 4.5 MHz |
| C. | 75 kHz |
| D. | 455 kHz |
| Answer» B. 4.5 MHz | |
| 8436. |
In an end fire array, the radiation pattern |
| A. | is in the plane of array |
| B. | is at right angles to array |
| C. | is at an angle to the plane of array |
| D. | either (b) or (c) |
| Answer» B. is at right angles to array | |
| 8437. |
Armstrong FM transmitter uses |
| A. | LC oscillator |
| B. | crystal oscillator |
| C. | RC oscillator |
| D. | either (a) or (c) |
| Answer» C. RC oscillator | |
| 8438. |
At a given probability of error, binary coherent FSK is interior to binary coherent PSK by |
| A. | 6 dB |
| B. | 3 dB |
| C. | 2 dB |
| D. | 0 dB |
| Answer» C. 2 dB | |
| 8439. |
In a TV receiver the video IF amplifier provides a gain of about |
| A. | 5 dB |
| B. | 20 dB |
| C. | 60 dB |
| D. | 200 dB |
| Answer» D. 200 dB | |
| 8440. |
Which of the following analog modulation scheme requires the minimum transmitted power and minimum channel bandwidth? |
| A. | VSB |
| B. | DSB-SC |
| C. | SSB |
| D. | AM |
| Answer» D. AM | |
| 8441. |
Switching systems |
| A. | are limited to small data networks |
| B. | require additional lines |
| C. | are not used in data system |
| D. | improve the efficiency of data transfer |
| Answer» E. | |
| 8442. |
Which one of the following statements is wrong. The radar cross-section of a target? |
| A. | depends on frequency |
| B. | may be reduced by special coating of non-spherical target |
| C. | depends on the aspect of target if it is non-spherical |
| D. | is equal to actual cross-sectional area for small targets |
| Answer» E. | |
| 8443. |
In an FM signal, the modulating frequency is 2 kHz and maximum deviation is 10 kHz. The bandwidth requirement is |
| A. | 2 kHz |
| B. | 10 kHz |
| C. | 5 kHz |
| D. | 32 kHz |
| Answer» C. 5 kHz | |
| 8444. |
In a TV receiver there is no raster, no picture and no sound. The most likely defective stage is |
| A. | power supply unit |
| B. | video output circuit |
| C. | horizontal oscillator |
| D. | balun |
| Answer» B. video output circuit | |
| 8445. |
Noise can be measured by |
| A. | D.C. voltmeter |
| B. | A.C. voltmeter |
| C. | either of the above |
| D. | none of the above |
| Answer» C. either of the above | |
| 8446. |
The effective length of antenna is different from actual length due to |
| A. | top loading |
| B. | end effects |
| C. | both (a) and (b) |
| D. | none of the above |
| Answer» D. none of the above | |
| 8447. |
In cellular telephone each cell is designed to handle |
| A. | 45 two way communications |
| B. | 90 two way communications |
| C. | 45 one way communications |
| D. | 180 two way communications |
| Answer» B. 90 two way communications | |
| 8448. |
A balun transformer gives an impedance transformation of |
| A. | 4 : 1 |
| B. | 2 : 1 |
| C. | 1 : 4 |
| D. | 1 : 2 |
| Answer» B. 2 : 1 | |
| 8449. |
A UPS contains |
| A. | rectifier |
| B. | inverter |
| C. | either rectifier or inverter |
| D. | both rectifier and inverter |
| Answer» E. | |
| 8450. |
In VHS format each video head is tilted from azimuth by |
| A. | 20 |
| B. | 10 |
| C. | 6 |
| D. | 1 |
| Answer» D. 1 | |