This is the Miscellaneous Multiples Choice Questions Part 8 of the Series in Communications Engineering. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including past Board Questions in Communications Engineering field (Electronics Systems and Technologies). In the actual board, you have to answer 100 items in Electronic Systems and Technologies within 5 hours. You have to get at least 70% to pass the subject. Electronic Systems and Technologies is 30% of the total 100% Board Rating along with Mathematics (20%), General Engineering and Applied Sciences (20%) and Electronics Engineering (30%).
Following is the list of multiple choice questions in this brand new series:
Continue with Part VIII of the Series
Choose the letter of the best answer in each questions.
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 2o?
- 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
400. 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