Miscellaneous MCQs in Communications Engineering Part VIII - Answers

Below are the answers key for the Miscellaneous Multiple Choice Questions in Communications Engineering Part 8.

351. ______ are transmission circuits interconnecting two different switching centers.

• a. Toll center
• b. Trunk circuits
• c. Hybrid circuits
• d. Intertoll circuits

352. The phone system begins with ______, which is the pair of wires that connects the central office to the user’s phone.

• a. Loop extenders
• b. Local change
• c. Switching office
• d. Local loop

353. When you dial the digit “8”, the corresponding low and high group tones are generated by the phone and sent to the central office are______.

• a. 852 and 1336 Hz
• b. 770 and 679 Hz
• c. 941 and 1477 Hz
• d. 770 and 1209 Hz

354. A signal travels via cables (propagation velocity 0.7 c) from New York to Los Angeles, a distance of 3000 miles. What are the talker echo and listener echo times?

• a. 46 ms and 78 ms
• b. 38 ms and 69 ms
• c. 46 ms and 69 ms
• d. 38 ms and 78 ms

355. The word telephone is derived from the Greek word tele, meaning _____, and phone, meaning ________.

• a. Type, audio
• b. Far, sound
• c. Scope, sound
• d. Far, handset

356. What are the second harmonics of the tones for the digit “3”?

• a. 1540, 2954 Hz
• b. 1394, 2954 Hz
• c. 770, 1209 Hz
• d. 1714, 1852 Hz

357. A European unit of the traffic intensity equal to 1/30 of an Erlang.

• a. Call second
• b. EBHC
• c. Erlang
• d. Call minute

358. A two state switching device containing one or more elements that have a low transmission impedance in one state and a very high one in the others.

• a. Crosspoint
• b. Coordinate switch
• c. Folded Network
• d. Expansions

359. Is the representation of a speech signal or other analog signal by sampling at a regular rate and converting each sample to binary numbers.

• a. QAM
• b. FSK
• c. PCM
• d. PAM

360. A murray loop is connected to locate a ground in cable between two cities 64 km apart. The lines forming the loop are identical. With the bridge balanced, R1 = 645 ohms and R2 = 476 ohms. How far is the grounded point (p) from the test end.

• a. 35.45 km
• b. 26.28 km
• c. 72.06 km
• d. 54.35 km

361. Refers to the specific of how these various waves travel under different circumstances.

• a. Scatter
• b. Propagation
• c. Waveguide propagation
• d. radiation

362. Travel in a straight line from the transmitting antenna to the receiving antenna.

• a. Ground wave
• b. Scatter
• c. Space wave
• d. Sky wave

363. Are intended to pass through the earth’s ionosphere and into space, or travel from a spaced-based transmitter to a receiver on the ground.

• a. Satellite waves
• b. Ground waves
• c. Line of sight
• d. None of these

364. Ducting is also called____.

• a. Super ducting
• b. Superrefraction
• c. Superdiffraction
• d. refraction

365. Frequencies in the UHF range propagate by means of

• a. Ground wave
• b. Surface wave
• c. Sky wave
• d. Space wave

366. An electromagnetic wave travel in free space, only one of the following can happen to them.

• a. Absorption
• b. Attenuation
• c. Refraction
• d. reflection

367. VLF waves are for some types of services because

• a. Of low powers required
• b. They are very reliable
• c. The transmitting antennas are of convenient size
• d. They penetrate the ionosphere easily

368. A region where the air pressure is so low that the free electron and ions can move about for some time without getting close enough to recombine into neutral atoms.

• a. Ionosphere
• b. Troposphere
• c. Sky
• d. Sky wave propagation

369. ________ is the distance between two wave fronts having the same phase at any given instant.

• a. Wavefront
• b. Wavelength
• c. Wave distance
• d. Field intensity

370. Modulation is used to ________.

• a. Increase the carrier power
• b. Reduce bandwidth used
• c. Allow the use of practical antennas
• d. Shorten the transmission channel

371. A pre-emphasis circuit improves the signal-to-noise of an FM signal by __________.

• a. Amplifying the higher audio frequency
• b. Boosting the bass frequency
• c. Amplifying the whole frequency
• d. Increase the carrier power

372. In an AM broadcast super heterodyne receiver, the

• a. Local oscillator operates below the signal frequency
• b. Mixer input must be tuned to the signal frequency
• c. Local oscillator frequency normally double the IF
• d. RF amplifiers normally works at 455 kHz above the carrier frequency

373. Carriers are spaced at 20 kHz, beginning at 100 kHz. Each carrier is modulated by a signal with 5 kHz bandwidth. Is there interference from sideband overlap?

• a. No
• b. Yes
• c. Maybe
• d. Sure

374. The modulated peak value of a signal is 10 V and the unmodulated carrier value is 8V. What is the modulated index?

• a. 0.80
• b. 0.25
• c. 0.50
• d. 0.75

375. What is the maximum suppression for a phase error of 2^o?

• a. 41.2 dB
• b. 35.2 dB
• c. 23.6 dB
• d. 12.7 dB

376. An information signal that is sent directly without modulating any carrier is called _________.

• a. Modulating frequency
• b. Baseband AM
• c. Carrier frequency
• d. Broadband AM

377. Superheterodyne receiver was invented by

• a. A.H. Armstrong
• b. H.E. Armstrong
• c. E.H. Armstrong
• d. H.A. Armstrong

378. Convert the RF signal to the intermediate frequency,

• a. Mixer
• b. Local oscillator
• c. Mixer and local oscillator
• d. Mixer and IF stage

379. ______ is a very important part of the receiving system.

• a. RF amplifier
• b. Mixer
• c. Detector
• d. AGC

380. The frequency used for out of band signaling under CCITT standard.

• a. 3825 Hz
• b. 3700 Hz
• c. Both a and b
• d. Either a and b

381. The following are advantages of the optical fiber except _____.

• a. Greater capacity
• b. Crosstalk immunity
• c. Safer to handle
• d. Lower initial cost of installation

382. The frequencies used for fiber optic system

• a. 10¹⁴ to 10¹⁵ Hz
• b. 10⁷ to 10¹⁰ Hz
• c. 10⁹ to 10¹² Hz
• d. 10¹¹ to 10¹¹ Hz

383. Plastic fibers have the following advantage over glass fiber:

• a. Flexibility
• b. Ruggedness
• c. Ease of installation
• d. Low attenuation

384. A site that contains the cellular radio equipment. It can have one or more _____.

• a. Base
• b. Central Business District
• c. boundary
• d. Coverage

385. A modulated method using frequency changes to transmit data. Usually only two frequencies are used.

• a. FM
• b. GSM
• c. FSK
• d. FCC

386. Is contained in the NAM (Number Assignment Module)

• a. ERP
• b. FDMA
• c. DTMF
• d. ESN

387. The amount of attenuation present in a waveguide is due to _________.

• a. The air dielectric filling the guide
• b. The fine coating of silver inside
• c. Losses the conducting walls of the guide
• d. I²R loss

388. The advantage of microwave baseband repeater over heterodyne repeater is:

• a. It improve noise performance
• b. It increase power output
• c. It provide drops and inserts
• d. All of these

389. The correctness and accuracy of the transmitted message content is:

• a. Verified by the modem
• b. Determined by the sender and receiver, not by the communications system.
• c. Ensured by use of digital techniques
• d. All of these

390. Transmission of binary signals requires ________.

• a. Less bandwidth than analog
• b. More bandwidth than analog
• c. The same bandwidth as analog
• d. A license from the FAA

391. Which of the following is a characteristic of a LAN?

• a. Parallel transmission
• b. Unlimited expansion
• c. Low cost access for low bandwidth channels
• d. Application independent interfaces

392. ADF means

• a. Audio Direction Findings
• b. Automatic Direction Finder
• c. Automatic Detection Finder
• d. Alternate Detection Form

393. A navigational system which employs gyroscopes, accelerometers and associated electronics to sense burning rates and accelerations associated with the rotation of the earth.

• a. CNS
• b. INS
• c. GPS
• d. VOR

394. It is referred to as the range and azimuth display.

• a. A-scan
• b. B-Scan
• c. C-Scan
• d. PPI

395. GCA operates with:

• a. DME
• b. Master and slave stations
• c. Ground-based radar
• d. Local radio stations

396. Bass response means:

• a. Maximum high frequency response
• b. Emphasizing the high audio frequencies
• c. By passing high audio frequencies
• d. By passing low audio frequencies

397. Sound intensity varies directly to the square of:

• a. Density
• b. Velocity
• c. Pressure
• d. frequency

398. Audience per person usually have an absorption coefficient in unit pert sq. ft. of :

• a. 3.5
• b. 4.7
• c. 6.7
• d. 7.4

399. Early reflected sound is also called as:

• a. Echo
• b. Reverberation
• c. Pure sound
• d. Intelligible sound

100. The optimum reverberation time for a 6000 cu. Ft. room is about:

• a. 2.0 sec
• b. 1.5 sec
• c. 1.1 sec
• d. 1.0 sec

The Series

Following is the list of multiple choice questions in this brand new series:

Miscellaneous Communications Engineering MCQs

PART 1: MCQs from Number 1 – 50                        Answer key: PART I

PART 2: MCQs from Number 51 – 100                   Answer key: PART II

PART 3: MCQs from Number 101 – 150                 Answer key: PART III

PART 4: MCQs from Number 151 – 200                 Answer key: PART IV

PART 5: MCQs from Number 201 – 250                 Answer key: PART V

PART 6: MCQs from Number 251 – 300                 Answer key: PART VI

PART 7: MCQs from Number 301 – 350                 Answer key: PART VII

PART 8: MCQs from Number 351 – 400                 Answer key: PART VIII

PART 9: MCQs from Number 401 – 450                 Answer key: PART IX

PART 10: MCQs from Number 451 – 500                 Answer key: PART X

Complete List of MCQs in Communications Engineering per topic

Series of Multiple Choice Questions in Electronics Systems and Technologies

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