This is the Section 5 Module 5 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 5
1. Noise rating curves → an agreed set of empirical curves relating octave-band sound pressure level to the center frequency of the octave bands
2. Flanking transmission → The transmission of sound from one room to an adjacent room, via common walls, floors or ceilings
3. Sound intensity → What is the sound energy per unit area at right angles to the propagation direction per unit time?
4. Phon → _______ is the unit of loudness level of a sound
5. Sound Intensity → ___________ is the average rate of transmission of sound energy in a given direction through a cross-section area of 1 sq. m. at right angles to the direction
6. Pitch and loudness → Sound wave has two main characteristics which are__________
7. Reverberation time → Required time for any sound to decay to 60 dB
8. Ultrasonic → Sound that vibrates at frequency too high for the human ear to hear (over 20 kHz)
9. Crystal → Which microphone will be damaged if exposed to high temperatures above 52 degrees Celsius?
10. 20 Hz to 20 kHz → What is the audio frequency range?
11. 95-100dB → What is the dB SPL of an auditorium with contemporary music?
12. 80-85 dB → What is the church dB SPL with speech reinforcement only?
13. Loudness → Intensity can also be called as _______
14. Loudness → _____________ is affected by the distance bet. The listener and the source of the sound and its intensity varies inversely with the square of this distance
15. octaves → Much of music is generally referred to in _________
16. Exciter → Distortion enhances intelligibility when an ____________ is added
17. Color killer → ____________ is used to eliminate color confetti
18. Microphone transducer → A _________ converts acoustical energy
19. diaphragm and generating element → All microphones have two basic components namely
20. Norris-Eyring → When the average absorption is greater than 0.2
21. Interval → The ratio of frequencies is termed
22. Pitch → A term which is subjective but dependent mainly on frequency and also affected by intensity
23. Stephen and Bate → For ideal computation of reverberation time
24. Sound Intensity → ______________ is the sound energy per unit area at right angles of the propagation direction per unit time
25. 1200 Hz → One octave above 600 Hz is _________.
26. W.C. Sabine → Laid the foundations of acoustic theory of buildings
27. Sound → An aural sensation by pressure variations in the air which are always produced by some source of vibrations
28. 4.7 units → The average absorption for a person is _______.
29. Isotropic → An antenna with a unity gain
30. 1 → What is the maximum efficiency gain of an isotropic antenna
31. isotropic radiator → It is useful to refer to an___________. When comparing the gains of directional antennas
32. Near the center of the vertical radiator → For a shortened vertical antenna, where should a loading coil be placed to minimize losses and produce the most effective performance
33. 1 -1000 W → Typical speech power
34. 1000 and 3000 Hz → The maximum intelligibility for voice frequency is located between
35. 300 to 3400 Hz → Presently, this is the “standard” frequency bandwidth for voice transmission
36. 4 kHz → What is the standard voice channel spacing
37. Sensitivity → The _________ of radio receiver to amplify weak signal and produce a desirable intelligence at the output speaker
38. MIN → A digital identification associated with a cellular system
39. 25 → How many seconds does a facsimile transmit a standard page?
40. 1.88 – 1.90 GHz → What is the frequency band of DECT?
41. 6000 Hz → Supervisory Audio Tone (SAT) has __________ frequency
42. 10 mW → What is the power output of PCS?
43. First Selector → Which of the ff. responds to the request of a subscriber by sending a dial tone?
44. 3 W → What is the typical output power of a cellular phone?
45. 825 – 845 MHz → Cellular phones transmit in the band from
46. 870 – 890 MHz → Cell phone receives in the band from
47. 50 dB → What is the sensitivity of a cellular receiver?
48. 3.4 – 6.425 GHz → What is the frequency range of C-band?
49. 2225 MHz → What is the local oscillator (mixer) frequency of the satellite with an uplink frequency in GHz Band?
50. Gallium Arsenide solar panel array → What kind of battery panels are used in some advance satellites?
51. C-band → What band does VSAT first operate
52. 14/11 GHz → The frequency of Ku band for satellite communications
53. 17 degrees → The radiation patterns of earth coverage antennas have a beamwidth of approximately
54. 1 → The efficiency of an isotropic radiator
55. 3 – 30 GHz → Most satellites operate in which frequency band
56. 500 MHz → What is the typical bandwidth of a satellite band?
57. 70 MHz → What is the common up-converter and down-converter IF?
58. QPSK → What modulation is normally used with digital data?
59. 500 – 600 ms →The round-trip propagation delay between two earth stations through a geosynchronous satellite is ______.
60. 0.09 dB → What is the average insertion loss of fusion splice in fiber optics?
61. 0.38 dB → What is the insertion loss of connector-type splices for a single mode fiber optics?
62. 5 → What is the allowable deviation ratio of commercial FM broadcast?
63. 20 kW → The maximum power suggested by KBP on 919-1312 AM broadcast station in Metro Manila is
64. 3.8 MHz → What is the chroma subcarrier signal for color television?
65. 36 kHz → The minimum frequency separation between Frequency of AM broadcasting station
66. 6:00 AM to 8:00 PM → For provincial station, the classification of prime time blocks for FM shall be
67. 525 → One complete NTSC scanning cycle field consists of how many lines
68. 60 Hz → The field rate in the NTSC television system
69. 25 kHz → What is the maximum frequency deviation for audio modulation in TV transmission
70. Y, I and Q → What are the three separate signals derived from a matrix in a color TV transmitter?
71. 54 -216 MHz → Range of a VHF television transmitter
72. 1.8 MHz → What is the approximate bandwidth occupied by the chrominance video signal for color TV?
73. 0% → What is the standard video level, in percent PEV for white?
74. push-pull amplifier → balanced amplifier
75. 15750 → The number of scanning lines is _____ per second
76. 30 → Picture frames are repeated at the rate of _____ per second
77. Sensitivity → A measure of how well the receiver can respond to very weak signals
78. 75 kHz → What is the allowable freq deviation of a commercial FM broadcast band?
79. Class C → The final amplifier is operated as
80. Improve the rejection of the image frequency → The main function of the RF amplifier in a superheterodyne receiver is to
81. 23.75 – 29.75 MHz → The frequency range for cable TV channel T-13
82. 806 and 192 MHz → The television frequency which are now allocated to the land mobile services
83. 12.2 – 12.7 GHz for downlink and 17.3 – 17.8 GHz for uplink → Direct Broadcast satellite based allocation
84. Antennafier → Antenna with an embedded amplifier
85. Antennaverter → Antenna that uses a frequency converter
86. delta matching system → What term describes a method used to match a high-impedance transmission line to a lower impedance antenna by connecting the line to the driven element in two places, spaced a fraction of a wavelength on each side of the driven element center?
87. gamma matching system → What term describes an unbalanced feed system in which the driven element is fed both at the center of that element and a fraction of a wavelength to one side of center?
88. stub matching system → What term describes a method of antenna impedance matching that uses a short section of transmission line connected to the antenna feed line near the antenna and perpendicular to the feed line?
89. pillbox antenna → sandwiched
90. honey antenna → broad-beam biconical horn that has an omnidirectional pattern
91. flat antenna → planar antenna that is on the same plane
92. test antenna → ______ used for measurement of antenna performance
93. dolph-chebyshev antenna → sidelobe level
94. HF → frequency band uses over-the-horizon long range tracking with low accuracy and resolution
95. push-pull amplifier → balanced amplifier
96. class A(vacuum tube) → __________ amplifier…. Anode current that conducts all of the time
97. class B(vacuum tube) → ________ amplifier …anode current that conducts at exactly half of the cycle
98. Class AB (vacuum tube) → ___________ amplifier…. Anode current that conducts more than half a cycle but not less than half a cycle
99. Class C (vacuum tube ____________ amplifier….. anode current that conducts less than half of the cycle
100. Fantastron → free-running
101. 60 wavelengths → an electrically large antenna which is greater than
102. the resistance decreases, capacitance increases → If the mobile antenna is decreased, and frequency decreases
103. Laser Altimeter → altimeter at the optical band
104. dual-beam antenna → strong clutter
105. Gregorian antenna → two concave mirrors
106. Stack up two yagis that are perpendicular at each other. The feed are both on the same plane and fed up at 90 degrees out of phase. → To make a linearly polarized antenna to a circularly polarized
107. twist-polarization → feed polarization