This is the Section 1 Module 2 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 2
1. Extended superframe – 576 channels
2. Delta Modulation – slope overload is common problem
3. T1 – most common carrier line for telephones
4. 100 dB - RF and IF gain in receiver
5. 0.9 – velocity factor for open wire
6. 0.8 – velocity factor for twin lead
7. Critical frequency of F2 – 8 MHz
8. Ephemeris – location of a celestial body in space
9. troposcatter – 350 MHz to 10 GHz
10. End impedance of HW dipole – 2500Ω
11. single hop night time range of F2 – 4130 km
12. 3300 m/s – speed of sound in wood
13. GSM/TDMA – cannot execute soft handoff because cell sites use different sets of frequencies to communicate with each other
14. 20 phons – typical loudness level of ticking watch
15. M88 – 88 mH coil; every 9000 feet
16. Hybrid Transformer – 2 wire to 4 wire converter
17. click – square wave; rounding off something
18. SDMA – Spatial Div. Multi Access; use same frequency in multiple focused beams aim at different areas
19. IS 95 – became CDMA 2000
20. International pitch A – 435 Hz
21. Hash – 128 bits sequence in digital signature
22. Envelope Delay Distortion – caused by frequency dependent attenuation chars of transmission lines
23. POP3 – Post Office Protocol version 3
24. Why use geosynchronous satellites? To simplify tracking requirements
25. BISYNC – not a bit oriented protocol
26. flag filed for SDLC/HDC – 7Eh
27. Bit stuffing – to prevent accidental flag fields?
28. Blank and Burst – interrupt voice feed to send control signals (cellular telephony)
29. fiber optics are preferred to satellites for long distance telephone transmission because of less delay
30. real time of info – found in circuit switching
31. mechanical splicing
32. fusion splicing – the ends are melted together
33. 2 mV – TV video signal level
34. for CATV : (noise free picture)
a. 1 mV for 75Ω
b. 2 mV for 300Ω
35. Synchronous demodulation – process of getting the info from the chroma signal
36. CW Doppler Radar – used by police
37. CTCS – Continuous Tone Control Squelch; low frequency tones only
38. EO 196 – control of PHILCOM SAT to NTC
39. P 5000 – fine for no permit (MPDP)
40. P 5000 – per unit fine of unauthorized cellphone service
41. P 100 K – paid up capital
42. P 1200 – permit for MPD
43. P 300- license for CATV head end
44. Differential Peak Detector – has a peak detector
45. Sun Detector – orientation of sunlight
46. Blooming – trapped gas pockets in fiber cables
47. Service numbers – 3 digit number with specialized service
48. smart card – card with embedded IC
49. armature – part of dc radio gen which is grounded to reduce radio noise
50. MPEG4 - current video compression standard
51. 6 to 10 dB – noticeable change in loudness level
52. noise figure: (with equalizer)
a. 330 MHz – 9.5 dB
b. 54 MHz – 7.5 dB
53. 12 dB – visual signal level for channels that have other than 6 MHz nominal separation
54. 3 dB – visual signal level for channels that have 6MHz nominal separation
55. 13 to 17 dB – sound carrier lower than visual carrier
56. Cross Luminance – diagonal patterns
57. S unit – 6 dB
58. MPDP – apply at NTC regional office of area to service
59. 24.3 kBaud/sec – modulation rate for D-AMPS
60. 150 µV – receiver preamp input (CATV)
61. SSB – 200 Hz shift results in material degradation
62. +- 25V – max voltage to apply (data)
63. GMDSS – Global Maritime Distress and Safety System
64. AMPS – 10 kbps
65. Positive Carrier Shift – insufficient grid mod at grid modulation circuit
66. Negative Carrier Shift – insufficient grid mod at high power modulation
67. 100 milliroentgents/week exposure
68. 0.5 milliroentgents per hour from 5 cm
69. camera pickup tube – yellow green is most sensitive
70. wan topologies:
a. leased line
b. circuit switching
c. packet switching
71. <5% - interference to visual signal level
72. Measuring rad exposure – device should have area max 10cm2 max linear dimension is 5cm
73. 3 channels – separation between geographically adjacent stations to minimize interference
74. downtilt – limit range
75. GPS – uses CDMA for multiple access tech
76. 1800 Hz – reference frequency for envelope delay distortion measurement
77. Two tone test – SSB method in testing AM transmitter
78. Pump laser – to higher energy level
79. MPEG2 – Discrete Cosine Transform
80. IMTS – Improved Mobile Tel System; Bell Labs, 1965 or 68
81. PON – not needing to install expensive equipment at every terminal
82. Ethernet – uses 3 level Manchester code
83. CT 2 – portable payphone booth
84. SSB - assigned frequency is 1.4 kHz above carrier frequency
85. Linear amplifier – frequency instability for J3E because there’s no carrier reference
86. Horn and slot – direct connection to waveguides
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