Communications Engineering Coaching Materials: Section 1 Module 7

This is the Section 1 Module 7 of the compiled Communications Coaching Materials taken from different sources including but not limited to Communications books, past Board Exams Questions, Journals and the Internet.

Communications Coaching Materials: Section 1 Module 7

This is the Section 1 Module 7 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 7

1. Speech power – typically ¼ to 1/3 of PEP

2. CATV channels – between channels 6 and 7 (wideband); above channel 13 (superband)

3. VCR data – FM modulation

4. Superjumbo group – 10,800 channels

5. GPS – user segment, space segment, control segment; main control – Falcon Air Base, Colorado, USA

6. Magic T – hybrid T

7. Feed horn – horn amplifier that feeds a reflector

8. 100 dB exposure – 20 mins

9. Datawire – term for the communication channel over which data is transmitted

10. Slope detector – vulnerable to noise degradation

11. Ratio detector – more amplitude dependent but lower demodulated signal level (50%)

12. Varactor diode (for direct FM) – 12:1 ratio of capacitance

13. IF amp – most of the receiver’s selectivity/gain

14. SSB signals – more prone to frequency distortion because there’s no carrier to serve as reference

15. Lattice modulator – most commonly used SSB modulator

16. Losses in fiber optic cable – material/absorption losses, scattering losses, dispersion losses

17. Splice is better that connectors because there is no air gap

18. PCS – plastic-clad silica; uses silicon plastic

19. Fiber construction:

Glass – low attenuation; brittle

Plastic – high attenuation

20. Radar – 2 types: continuous wave (CW) and pulsed

21. TACS – 1G system used in England; 8 kbps data rate

22. LIDAR – optical version of radar; light direction and ranging

23. Frequencies directly above 300 GHz – millimetric waves

24. Sunlight radiation – 300 nm - 2000 nm (UV to infrared)

25. Human ear – best response – 1- 4 kHz

26. If the desired area to capture cannot fit into the camera’s field of view, use a lens with shorter focal length

27. Ultor – main accelerating anode

28. Grid-dye meter/detector – for measuring RF current/power in antenna; for measuring resonant frequency of RF circuits

29. Hamming code – corrects 1 bit only

30. TDD – time division duplexing – 2 way communication channels are separated in time via time slots

31. Microwave communication is being used because of wide bandwidth

32. To protect against fading – frequency diversity; space diversity

33. Fresnel reflection – reflection of waves through 2 media; involves materials w/ different index of refraction; also involves angle; reflection of part of incident light

34. Initial payload – main satellite in the satellite launch

35. 8-VSB – standard for digital TV

36. Why digital TV? – possibly less BW, more immunity to noise, more signal processing

37. For UHF frequencies, transmission lines are used in place of LC networks.

38. Interlacing – technique to reduce flicker of TV picture w/o increasing BW

39. No. of scanning lines (conventional TV) – 525

40. Effective no. of scanning lines – (utilization factor) (525) = resolution of picture

41. HDTV – up to 1125 lines; 5 times more video info compared to conventional TV picture

42. Video signal w/o sync pulse – noncomposite video signal

43. Commercial (analog) telephone service – NTT, 1979

44. Problem of 1G – a phone’s code can be stole and copied – clone fraud

45. Why is it hard to transmit music using SSB? – it is difficult to produce 90° phase shift for AF in the 5-10 kHz range

46. Modern pool – alternative to having a dedicated modem + telephone line connection for each workstation

47. Inertial Navigation Systems (INS) – part of most aircraft/ships today

48. Republic and Titanic (1910 and 1912) – sinking led to mandatory 24-hr ship-to-shore communications

49. Anisochronous – no relationship in the time interval (“chronous”) between Tx and Rx data

50. Dolby AC-3 surround sound – sound with compressed data rates

51. Microphones:

Carbon – economical

Dynamic

Condenser – weak response

52. Broadband wireless access for fixed, nomadic, mobile:

In MHz:

450-470                               2400-2483                          5150-5350       

1900-1910                          2500-2700                          5470-5850

1980-1990                          3400-3600                         10150-10650

53. SUF for 3G (per MHz, M-million):

Frequency                           paired                                 unpaired

5 MHz                                  P 5M                                   P 3M

5th-10th                               8M                                        6M

10th-15th                             10M                                      8M

>15th                                   15M                                       12M

54. Ambiophony – adjusting reverberation by providing loudspeaker feedback

55. 2% of main signal – to provide minimum interference

56. Bluetooth – IEEE 802.15; 720 kbps; 1mW

57. Wimax – 802.16

58. Zigbee – 802.15.4; cost-efficient; low power; low data rate

59. Wifi – 802.11b; 11 Mbps; 54 Mbps

60. Vinton Cerf – father of internet

61. ITU-T – telecommunications standards bureau

62. William Gibson – 1984; coined “cyberspace” in “Neuromancer

63. EO 467 – national policy on the operation and use of international satellite.

64. EO 205 – regulation of CATV

65. EO 101 – improvement of LEC service

66. EO 469 – satellite; March 17, 1998

67. 1% harmonic distortion for CATV

68. Range of CDMA – 13 miles; BW = 1.23 MHz

69. Birth of WWW – 1991

70. 1918 – superheterodyne receiver; Edwin Armstrong

71. 820 nm – 2.5 dB Rayleigh loss

72. 0.7 μm – 100 μm –   IR wavelength

73. Radio Act of 1910 – first attempt at radio regulation

74. Hydrazine – fuel for jet thrusters

75. Middle C – 262 Hz

76. Cavity resonator – high Q parallel LC circuit

77. Hoghorn – parabolic cylinder plus horn antenna

78. 15 yrs – max permit length of CATV operator authentication

79. Iridium – 780 km; 66 satellites

80. 1978 – first GPS satellite launched

81. L band – used for navigation

82. 3G – “2 to 4 times” 2G

83. 2G – 3000-20,000 people per cell site

84. 1G – 1000 people, 50 radio channels

85. Cell site – 10-50W

86. П-L network/ inductive coupling – against harmonics/ greatest harmonic suppression

87. Digital microwave – PSK/QAM

88. Cable TV supplying power and signals – 30 Vac or 60 Vac

89. UWB – 20/30 ft.; 500 MHz or 20% of center frequency

90. Randall and Boot – some type of magnetron

91. Beamwidth of horn antenna – 10° - 60°

92. Thick Ethernet – 10 Base 5 (old thick Ethernet)

93. Thin Ethernet – “cheapernet”

94. Button microphone – used in telephones

95. Telemetry – 481.25 - 481.725; 486.25 - 486.725

96. CB – 26.965-27.475 MHz

97. International AM station – min 50 kW

98. P 900 – license fee for head-end licensing

99. F-type connector – commonly used for TV, etc.; cheap

100. Cyan – 90° leading color burst

101. 125 μm – cladding diameter

102. Highest sunlight power – at 500 nm

103. IS-136 – North American digital cellphone standard

104. IS-95 – CDMA

105. Gyrotron – high power; >100GHz; USSR 1971

106. Backward-wave oscillator (BWO) – TWT + slow wave structure (RF + e-beam)

107. CB antenna height – 60 ft. above ground; 20 ft. above building

108. Jabber – random data sent by NIC

109. 9 pm - 7 am -  no push/broadcast messages in paid subscription for such messages

110. For 2 kW transmit power, 2860W power

111. Velocity factor – 0.9 – twin lead; 0.9 – open wire; 0.5-0.9 in general

112. Shift register – used as bit-splitter

113. Phase splitter – push-pull amplifier

114. Input of quadrature phase detector – differential amplifier

Complete List of Communications Engineering Coaching Materials


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