(Last Updated On: December 21, 2017)
This is the Section 5 Module 20 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 5 Module 20
QUESTIONS |
ANSWERS |
1. A parabolic antenna in which the feed radiator is mounted at or behind the surface of the concave main parabolic reflector dish. |
Cassegrain antenna |
2. The downlink frequency or base station to mobile station frequency band in GSM 1800. |
1805-1880 MHz |
3. The nominal channel spacing of time division duplexing (TDD). |
5 MHz |
4. In the IS-95A cellular service, the base station transmit frequency is ___ above the mobile station transmit frequency. |
45 MHz |
5. The installation tension that can be given to a lightweight internal cable without causing damage. |
100 N |
6. Class B-1 FM broadcast stations with an authorized transmitter power of 500 watts, shall in no case have an effective radiated power lower than ____. |
1000 W |
7. The fiber number that has the typical color of orange in multi-core fiber cables. |
orange |
8. The installation tension that can be given to a more rugged fiber cable without causing damage. |
10000 N |
9. Aqua is the typical color of fiber number ___ in a multi-core fiber. |
12 |
10. A signaling path provided by a cable television system to deliver to subscriber terminal signals that are intended for reception by equipment other than a television broadcast receiver only when used with auxiliary equipment. |
Class III |
11. The time it takes to transmit 1000 kbps graphic image via a 10 Mbps cable modem. |
60 seconds |
12. A proprietary channel bonding equipment that can boost network up to 108 Mbps in the Wi-Fi world. |
Super G |
13. In cable television, the receiving antenna should be cut to respective channel frequency for optimum reception with a front-to-back ratio not less than ___dB |
18 |
14. The ideal reverberation time of which is 0.8-1.2 s |
Cinema |
15. What should be avoided inside an acoustical room? |
Long echoed voice |
16. One of the sources of errors of GPS signal is ionospheric effect which contributes ___ of error. |
+/- 5 m |
17. The first Atlantic telephone cable to use optical fiber that went into operation in 1988. |
TAT-8 |
18. When placing cardiods-patterned microphones, each microphone should be at least four times as far as from the next one as it is from the sound source. This is known as a ___ rule. |
4-to-1 |
19. The ITU-T recommendation for data compression that was issued in 1990 and uses the Limpel-Ziv Welch compression algorithm. |
V.42bis |
20. A TV broadcast mainly used in Western Europe. |
PAL B/G |
21. A tape format used in video recording that has a track scanning rotation seep of 1800 rpm. |
Hi8 |
22. The error correction code used by digital video cassette (DVC). |
REED-SOLOMON CODE |
23. In composite video signal measurement, what corresponds to 0 IRE value? |
Blanking pulse |
24. In composite video signal measurement, what corresponds to 100 IRE value? |
Pure white |
25. The equation for luminance for TV. |
0.3R-0.59G+.11B |
26. The TV standard which tends to replace PAL/SECAM in Europe. |
DVB-T |
27. At what channel does superband cable television starts. |
Channel 23 |
28. The aural deviation for television. |
+/- 25KHz |
29. A3A is previously known as _____, reduced carrier. |
R3E |
30. It has the compression of 200:1. |
MPEG 2 |
31. In microwave communications, the maximum obstruction which a microwave link can overcome. |
40% |
32. In Hamming code, there are ___ bits and ____ bits for each parity checking. |
4, 3 |
33. How many mastergroups are there in a jumbogroup. |
6 |
34. This is done to digital bits of data due to circuitry action so as not to have an undesired shift. |
Reduction of jitter |
35. Aperture for microwaves |
10-60 m |
36. Ratio of radiographic contrast with grid to that without a grid. |
Contrast Improvement Factor |
37. Antenna used when there are LC. |
Trap antenna |
38. In _____ 1G Mobile phone with the Nordic Mobile Telephone (NMT) system was introduced. |
1981 |
39. The "call handoff" feature was invented to allow mobile-phone users to travel during the same conversation. |
1984 |
40. For FM stereo, the maximum distance covered is significantly reduced, this is due to the presence of the _________ kHz subcarrier modulation |
38 |
41. |
0.45-0.55 |
42. Private operational fixed microwave is on the range of ________ dB. |
12.2-12.7 |
43. Measurement for protocols. |
dBx |
44. Rate for the scanning of 525 lines. |
1/30 |
45. As per Philippine standard, frequency allocation of AM Radio Broadcasting is from__________KHz. |
526.5-1705 |
46. Type of AM which operates at nighttime under 250 W or off-air, field strength up to 140 mV/m at 1 km. |
Class D |
47. |
15.27 |
48. The coding scheme which has the easiest…. |
BPRZ |
49. The bandwidth covered by the FM for hearing. |
50 Hz-15KHz |
50. The most sensitive frequency for human hearing. |
1-5 KHz |
51. What type of curve does our ear for telephone used. |
A-weighted curve |
52. How many ISDN channels are there? |
6 |
53. For a reflection of 20 dB, __% is for loss and __% is absorbed by the load. |
1, 99 |
54. Payment for a 1 MHz bandwidth |
500,000 |
55. Paid up capital on 3G. |
100M |
56. How many horizontal lines are blanked in TV? |
42 |
57. Downlink (receiving) assigned to GPRS |
28-64 kbps |
58. Disadvantage of slope detection of FM |
No noise discrimination |
59. The next channel if there is accommodating the 88.1 MHz channel. |
94.1 MHz |
60. The reverberation time for clear speech. |
2 secs |
61. The maximum BER for 99.97% |
1 in 10 ^3 |
62. For illuminating the transducer through the fiber, tungsten halogen lamps or broadband, ____________ light emitting diodes are suitable. |
GaAlAs |
63. 802.11 legacy data rates approximately |
2 Mbps |
64. High definition TV picture contains about __________ times as much as info as the present NTSC TV. |
5 |
65. IMTS2000 maximum data rate for stationary user is |
2Mbps |
66. The process of adjusting the orbit of a geostationary satellite so that it appears to remain stationary above a point on the earth. |
Station keeping |
67. The wavelength commonly used on the modern long distance fiber communications system. |
1550 nm |
68. HDTV compare with NTSC analog. |
12 to 18 dbm |
69. Super refraction |
Ducting |
70. In microwave communication, what concepts may be used to analyze interference by obstacles near the path of a radio beam? |
Fresnel zone |
71. |
connector |
72. In data communications, a 2400 bps modem running Class 4 would appear to operate at ______ bps. |
2900 |
73. The full IEEE 1394b specification supports optical connections up to 100 meters in length and data rates all the way to _______ gbps. |
3.2 |
74. What wavelength has the minimum loss in optical fibers? |
1550 nm |
75. Fine for unauthorized servicing of mobile telephone. |
5000/year |
76. What is the maximum power allowable for remote pick up stations used as broadcast auxiliary services for AM and FM broadcast stations. |
35 W |
77. Absorption coefficient of a surface material to absorb sound energy. |
0 |
78. It is an error-correcting code used for correcting transmission errors in synchronous data streams. |
Hamming in Code |
79. Variation in signal loss. |
Fading |
80. It is often defined as the loss incurred by an electromagnetic wave as it propagates in a straight line through a vacuum with no absorption or reflection of energy from nearby objects. |
Free Space Path Loss |
81. Sampling of an analog signal using a sample-and-hold circuit that the sample has the same amplitude for its whole duration. |
Flat-topped Sampling |
82. Caused by the difference in the propagation times of light rays that take different path down a fiber. |
Acceptance Modal dispersion |
83. Closely related to acceptance angle and is the figure of merit commonly used to measure the magnitude of the acceptance angle. |
Numerical Aperture |
84. Actual user info conveyed through the system. |
Payload |
85. A navigational technique that determines position by extrapolating a series of measured velocity increments. |
Dead reckoning |
86. Standard that describes Ethernet-type networks is |
IEEE 802.3 |
87. The word “Base” in 10BaseT means |
The cable carries baseband signals |
88. The primary audio channel remained at 50Hz to 15KHz, while an additional SCA channel is frequency translated to the _________ passband. |
60 KHz to 74 KHz |
89. The fastest output rate of change (baud) is also equal to ______ of the input bit rate. |
½ |
90. The sampling process alters the frequency spectrum and introduces an error called |
Aperture Error |
91. Signal rate of RS 232 normally used as interface between DTE and DCE. |
20 kbps |
92. An AM broadcast service area in which groundwave field of 1mV/m (60 dBu) is not subjected to objectionable interference or objectionable fading. |
Primary service area |
93. BW for fiber optics. |
900 THz |
94. International frequency distress for radio telephony |
2128 KHz |
95.Bit rate of STS-1 |
51.84 Mbps |
96. Telephone switch that connects only to other switches. |
Tandem |
97. 802.15.4 also known as |
Zigbee |
98. typical range of vidicon dark current |
0.2 microampere |
99.Shifting of antenna pattern so that the major lobe is at angle below the horizontal. |
Down tilt |
100. Ethernet system that uses a special “Thick Ethernet” |
A standard classical |
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