This is the Section 1 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 1 Module 6
1. EO 436 – governing operations of CATV
2. EO 205 – regulation of CATV
3. Office Order 87-08-2004 – mobile phone dealer’s permit
4. 07-08-2004 – Mobile phone repair
5. 08-08-2004 – Mobile phone dealer/retail/base/purchase/sale
6. Horn – most commonly used microwave antenna
7. SSB – uses mechanical filters
8. Surface Acoustic Wave (SAW) filter – for RF filters (TV frequencies)
9. Plumbicon (lead oxide) – minimum lag
10. +6 VU (volume unit) – VF level to be placed on voice signals
11. +0 VU – VF level to be placed on telephone line/channel
12. Despun antenna – spins to focus on a fixed location on the earth
13. Attitude control – orientation of satellite on relationship to earth and sun
14. Apogee kick motor – rocket motor that is regularly employed on artificial satellites destined for a geostationary orbit.
15. TTC – Telemetry and Tracking Control
16. Helical antennas – used because of Faraday effect
17. Faraday screen – minimize losses (for transmitter)
18. Analog cell phone:
Class I – 0.6W
Class II – 1.6W
Class III – 3W
19. 121.5 MHz – aeronautical distress frequency
20. 2182 kHz – maritime distress frequency
21. LORAN C/D – 100 kHz; 460m or ¼ mile absolute accuracy, 100 m relative accuracy
22. Class I – Cable TV Channel/Station-- off-the-air channels, DBS feeds
23. Class II – w/o auxiliary equipment – scrambling
24. Class IV – provides signaling path
25. Discone antenna – vertical polarization; broadband
26. Cellular phone FM (AMPS) – ±12 kHz deviation
27. 5150 m/s – speed of sound in steel at 1 atm
28. TDM – 8 μs per time slot
29. AMPS – 10 kbps per channel
30. D-AMPS – 30 kbps – combines 3 AMPS channels
31. Cable TV:
16 dB - matching (RF)
28 dB – terminal isolation
40 dB – sound carrier isolator
60 dB – spurious radiation rejection
80 dB – cross modulation
-60 dB – adjacent channel isolation
± 1 dB – audio signal level
2 dB
36 dB – video SNR for modulator
32. 3G – UMTS (universal mobile telephone system); 2001
33. IS-95 – not TDMA; Direct Sequence Spread Spectrum- Mobile and Telephone
34. IMT 2000 – 144 kbps for fast vehicles; 384 kbps for pedestrians and slow vehicles
35. PD 1986 – MTRCB
36. EO 59 – mandatory interconnection of telecommunications networks
37. 1550 nm – used because of least losses
38. RA 9292 – approved by GMA on April 17, 2004
39. EO 196 – Philippine Satellite
40. Satellite closet – offshoot of TTC (building code)
41. Doppler radar – specialized radar that makes use of the Doppler effect to produce velocity data about objects at a distance.
42. Helmholtz resonator or Helmholtz oscillator is a container of gas (usually air) with an open hole (or neck or port).
43. GPS – 20,200km; 60° spacing between orbital planes; 6 orbital planes; 55° inclination
44. Poke-through – in building construction (telephone installation); wires poke through fire-resistant floor
45. Firewire – connects cameras, etc. to computer
46. H.261 – video conferencing over telephone line
47. MP3 – MPEG-2 audio layer 3
48. MPEG-1 – low-rate video used in CD- ROM
49. MPEG-4 – DivX video compression
50. PL-259 – UHF connector
51. Type N connector – coax connector; expensive but good
52. 7:8 – dissonant tone ratio
53. Consonant tones – pleasant tones; antonym of dissonant
54. 1:1.38 – max. tolerable VSWR of something
55. American concert A – 440Hz
56. One octave above middle C – 524 Hz
57. Proxima centauri – nearest star to solar system
58. Aurora borealis – rapid fluttering; ionic disturbance
59. 10 octaves – human hearing range
60. Ionosonde – measures virtual height
61. Brillouin scattering – slight frequency change; modulation of light by the thermal energy in the material; produces phonons and photons
62. Mie scattering – caused by particles that have the size of wavelength
63. Splatter – excess sidebands
64. J3E – 1.4kHz difference between carrier and assigned frequency
65. F3 – for voice
66. Data rates:
GPRS – >170 kbps
EDGE – >384 kbps
3G – > 2 Mbps
67. 6 MHz terrestrial – 19.39 Mbps
68. 6 MHz data (cable modem) – 27 Mbps
69. CB SSB – 12W PEP
70. 3.1 m3/person – cinema volume level
71. NAVTEX – texting system for ships; maritime safety weather; narrowband direct printing telegraphy
72. Slot antenna – used for navigation systems; aerodynamic
73. Hole – for wavelength and waveguide wavemeter coupling
74. Probe – coupling for waveguide
75. Loop – coupling for waveguide
76. 4.5 MHz + 1 MHz – intercarrier
77. 1.25 MHz + 250 kHz – from lower edge
78. 3.579545 MHz – chroma subcarrier
79. V.90 – 56 kbps for telephone line
80. Flicker noise voltages:
0.02-0.2 μV – metal film
0.05-0.3 μV – carbon film
0.1-3.0 μV – carbon composition
0.01-0.2 μV – wirewound
81. IMT2000 – not 3G
82. 02 absorption – 5 mm, 2.5 mm
83. Water vapor – 1.35 cm, 1.7 mm
84. IMSI – international mobile subscriber identification
85. MIN – mobile ID number
86. WCDMA – 1.25W
87. DWDM – dense wavelength div mux
88. COW – cellsite; emergency purposes; on flatbed of tractor or trailer
89. Stripline – 2 ground planes; “sandwich”
90. Microstrip
91. 802.3 – defacto Ethernet; CSMA/ CD LAN
92. 100 Mbps Ethernet – 100 m
93. Token ring – 4 or 16 Mbps
94. UTC – universal coordinated time
95. Why are cable channels converted to VHF from UHF? – to reduce losses in coax cable
95. Hard line – coax with hard shield
96. Twinax
97. Slow wave structure – forces electron beam to move slowly
98. C-band transponder guard band – 4 MHz
99. IF for TV receivers – 36-46 MHz
100. Electron spin – in ferrites; due to magnetic field; precession
101. PVC – cover of coax
102. Polytetraflouroethylene – Teflon
103. Polyethylene – good for outdoor cables
104. Cross-over cable – low capacity/number of computers; will do in place of a hub
105. Electroluminescence – LED action
106. Radiometry – measuring RF spectrum
107. Photometry – technique of astronomy concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation.
108. Luminosity – lumens/watt
109. Aperture antenna – antenna aperture or effective area is a measure of how effective an antenna is at receiving the power of radio waves.
110. 40 km – microwave repeater distance
111. 56 km – TV broadcast radius
112. Omega – raw system; 88-98% of earth
113. Radar – depends on:
Distance – speed of pulse
Altitude – vertical beamwidth
Direction – directivity of antenna
114. UHF channel – noise figure 9 dB or better
115. RLE – takes advantage of redundancies in bit stream
116. GFSK – modulation used in Digital European Cordless Telephone (DECT)
117. GSM – 13 kbps speech coding rate
118. CATV and head-end operation – requires licensed commercial telephone operator
119. Critical frequency of E layer – 4 MHz
120. Gimmick – wire that acts as a capacitor; capacitance can be changes by bending wire to one side or another
121. Public key – for encrypting signal
122. Private key – for decryption
123. Why analog transmission rather than digital transmission of CATV in fiber optic medium? – easier to just modulate whole RF spectrum that having to demodulate, demux, encode, etc.
124. On-hook loop voltage (telephone) – -48 Vdc
125. Side tone – echo from Tx side to Rx side
126. Ringback – sent to the calling station to inform that call is in progress
127. Erlang C – blocked calls delayed until served/satisfied
128. Cell site D/R ratio – distance required before reuse; R – cellsite radius; “Cochannel Interference Reduction Factor”
129. Satellites – “spatial isolation” – frequency reuse by aiming beams at different locations (spaced-enough)
130. Base station – $500,000 - $750,000 to put up
131. 1 dB, 2 dB – visual signal level throughout video channel BW
132. Why is it easier to analyze transmission lines at low frequency? – low L and C, leaving only resistive component
133. Multi-mode fiber – easier to work with than single mode; wider acceptance angle
134. Why is height still important for mobile telephone transmitter antenna? – for more direct path; less reflections
135. Soliton – any optical field that does not change during propagation because of a balance between nonlinear and linear effects in a medium
136. SONET – brings together the North American and European digital mux hierarchies
137. Passive optical network – all-fiber access systems intended for residential applications
138. Single-mode fiber – width = 3 (wavelength of the light carrier)
139. Cryogenic cooling – lowers the operating temperature of receivers to reduce noise levels
140. SSB – envelope delay distortion test – 1800 Hz
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