This is the Section 2 Module 6 of the compiled Communications Coaching Materials taken from various sources including but not limited to past Board Examination Questions in Electronic System and Technologies (EST), Communications Books, Journals and other Communications References. This particular Coaching Notes in Communications Engineering has random Questions and Answers in random topics. Make sure to familiarize each questions to increase the chance of passing the ECE Board Exam.
Communications Engineering Coaching: Section 2 Module 6
301. Which coaxial connector is a more complex and expensive but do a better job in maintaining the electrical characteristics of the cable through the interconnections
ANSWER: N type connector
302. What type of digital circuit is used as a bit splitter?
ANSWER: shift register
303. What sound characteristics relates to a sonic time pattern?
304. What is considered the most obvious conveyor of information?
305. What is the amount of sound reduction provided by a barrier – wall, floor or ceiling called?
ANSWER: transmission loss
306. In cellular system, the average lead time to install a new base station is approximately ________ months to a year
307. What is considered the threshold of audibility at 3000 Hz?
ANSWER: 10^ -12 W/ m^2
308. Which of the following is NOT a porous absorber?
ANSWER: membrane absorber
309. The American concert pitch A is equivalent to which of the following frequencies?
ANSWER: 440 Hz
310. The international pitch A is equivalent to __________ Hz.
311. What does CPE stands for
ANSWER: Customer Premise Equipment
312. Around the neck of the picture is a structure of a magnetic coil called __________
ANSWER: deflection yoke
313. What is the counterpart of Zigbee?
314. The term Bluetooth is named after the king?
ANSWER: Danish king Harald Blattand
315. When was world wide web introduced?
316. A device that connects two dissimilar networks and performs the protocol conversion
317. Comb filter is used to __________
ANSWER: cancel chroma crosstalk
318. A laser used as an energy source to excite electrons into a higher energy state.
ANSWER: Pump laser
319. In the Amps systems, a sine wave above the voice frequency range, transmitted on the voice channel along with the voice, used by the base station to detect loss signal.
ANSWER: Supervisory Audio tone (SAT)
320. A mobile telephone service, now obsolescent, using trunked channels but not cellular in nature.
ANSWER: Improved mobile telephone service (IMTS).
321. In cellular communication, it is the interrupting the voice channel to send control information.
ANSWER: Blank-and-burst signaling
322. The process of adjusting the orbit of a geostationary satellite so that it appears to remain stationary above a point on earth.
ANSWER: Station keeping
323. In Satellite communication, continuously adjusting the position of a directional antenna on the ground, so that it always point at the satellite.
324. The video signal level representing maximum luminance
ANSWER: peak white
325. The frequency at which a VCO operates when its control voltage is zero
ANSWER: Free running frequency
326. The portion of scanning lines in a video system that, on average, can be used in determining vertical resolution
ANSWER: Utilization factor
327. It is a form of spread-spectrum communication in which the RF carrier continually moves from one frequency to another according to a prearranged pseudo-random pattern
ANSWER: Frequency hopping
328. A microwave transmission line that consists of a circuit board, working against two ground planes, one on the top and one on the bottom of the board.
329. An error-correcting system in which errors are connected at the receiver using redundant transmitted data without using retransmission request.
ANSWER: Forward Error correction (FEC)
330. It is a switching network that does not use a hierarchical structure but instead relies on a computer to find the most direct route between two points
ANSWER: Flat network
331. A representation of a signal’s power or amplitude as a function of frequency.
ANSWER: Frequency domain
332. It is a detector for suppressed-carrier AM signals that works by multiplying the signal with the regenerated signal.
ANSWER: Product detector
333. Most communication satellites are geostationary to simplify tracking requirements, but low-earth-orbit satellites are coming into increasing use especially for mobile communications, because shorter distance to the satellite results in stronger signals.
334. What feature of SONET allows data spin with different paths to be synchronized?
ANSWER: Payload Pointer
335. Why do splices have lower loss than connector pairs?
ANSWER: Splices don not have the air gap that most connector have.
336. Why a matched line is indistinguishable from infinitely long line as seen from the source?
ANSWER: No energy is reflected from matched load, so from the source it appears as if energy put into the line continues to move down the line forever
337. Why does a higher impedance line have lower copper loss than a lower impedance line, all other things being equal?
ANSWER: A high impedance line has a lower current for a given power level than does a line lower characteristic impedance.
338. All else being equal, larger receiving antennas receiver a stronger signal than smaller antennas. Why is this?
ANSWER: They have a greater effective area so they intercept a greater proportion of the radiated energy
339. What is the effect on the resonant frequency of a monopole antenna of inserting a coil at its base?
ANSWER: Adding inductance to an antenna lowers its resonant frequency
340. Which of the antennas are suitable for direct connection to a waveguide?
ANSWER: Horn and slot antennas are suitable for direct connection to the waveguides
341. How can the polarization of a simple antenna be determined?
ANSWER: The polarization for most simple antennas is the same as the axis of the radiating element
342. How does stacking omnidirectional antennas or arrays vertically results in an increase in gain while keeping the horizontal radiation pattern omnidirectional?
ANSWER: Stacking these antennas reduces the radiation in the vertical plane, increasing gain in the horizontal plane.
343. Why is frequency reuse important in cellular systems?
ANSWER: Cellular systems increase their traffic capacity by reusing frequencies at relatively small distances.
344. Which of the following applies for a monochrome picture?
ANSWER: chroma amplifier off
345. Why is multimode fiber easier to work with than single mode fiber
ANSWER: Mutlimode fiber has a much larger core diameter, and also a larger numerical aperture, than single mode fiber
346. The noise-reduction effect that occurs with strong FM signals.
ANSWER: Threshold effect
347. What is the main difference between a wireless hub and a wireless bridge?
ANSWER: The bridge needs to have much more powerful transmitter because it needs to have greater range
348. Why is antenna height in mobile communications, even when the distance involved are much less than the distance to the horizon?
ANSWER: Greater antenna height results in reduced multipath interference and fewer obstruction in direct path
349. Why does modern long distance fiber communications system use wavelength on the order of 1550nm?
ANSWER: The loss in glass fiber is lowest at a wavelength of approximately 1550nm
350. The maximum distance that can be used with a fiber link can be limited by either loss or dispersion Limitation due to losses are expressed in a loss budget. While dispersion is expressed in terms of either bandwidth-distance product or rise time.
351. Why is low dispersion more important than low loss in modern fiber communication systems?
ANSWER: Losses can be made up by the use of optical amplifiers, but dispersion can only be corrected by using regenerative repeaters, which are more complex and expensive.
352. Why is loose-tube construction preferred when cables must be pulled through ducts?
ANSWER: Loose-tube construction reduces the pulling stress on the fiber.
353. According to NTC, what is the Spectrum User Fee (SUF) for the allocated and assigned for Paired 3G radio frequency bands for the first 5 MHz?
Answer: P5, 000,000.00 per MHz
354. According to NTC, what is the Spectrum User Fee (SUF) for the allocated and assigned for Paired 3G radio frequency bands for each additional 1MHz or fraction thereof in excess of the first 5 MHz but not exceeding 10 MHz?
Answer: P8, 000,000.00 per MHz
355. According to NTC, what is the Spectrum User Fee (SUF) for the allocated and assigned for Paired 3G radio frequency bands for each additional 1MHz or fraction thereof in excess of the first 10 MHz but not exceeding 15 MHz?
Answer: P10, 000,000.00 per MHz
356. According to NTC, what is the Spectrum User Fee (SUF) for the allocated and assigned for Paired 3G radio frequency bands for each additional 1MHz or fraction thereof in excess of the first 15 MHz?
Answer: P15, 000,000.00 per MHz
357. According to NTC, what is the Spectrum User Fee (SUF) for the allocated and assigned for Unpaired 3G radio frequency bands for the first 5 MHz?
Answer: P3, 000,000.00 per MHz
358. According to NTC, what is the Spectrum User Fee (SUF) for the allocated and assigned for Unpaired 3G radio frequency bands for each additional 1MHz or fraction thereof in excess of the first 5 MHz but not exceeding 10 MHz?
Answer: P6, 000,000.00 per MHz
359. According to NTC, what is the Spectrum User Fee (SUF) for the a allocated and assigned for Unpaired 3G radio frequency bands for each additional 1MHz or fraction thereof in excess of the first 10 MHz but not exceeding 15 MHz?
Answer: P8, 000,000.00 per MHz
360. According to NTC, what is the Spectrum User Fee (SUF) for the a allocated and assigned for Unpaired 3G radio frequency bands for each additional 1MHz or fraction thereof in excess of the first 15 MHz?
Answer: P12, 000,000.00 per MHz