This is the Section 2 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 2 Module 2
61. A wide area blackout of HF radio communication as well as loss of radio contact for about an hour on the sunlit side of Earth.
62. Moderate limited blackout of HF radio communications on sunlit side occur , loss of radio contact for tens of minutes
63. Limited blackout of HF radio communications on sunlit side occur, loss of radio contact in an occasion.
64. What is the orbital time of MEO satellite?
ANSWER: 5 to 12 hrs
65. Is the process by which a permanent, low-loss, high strength, welded joint is formed between two optical fibers?
ANSWER: fusion splicing
66. Involves many different approaches for bringing the two ends of the fibers into alignment and then clamping them within a jointing structure or gluing them together__________
ANSWER: mechanical splicing
67. With this method, the signal modulates a carrier that is linearly swept over the band being used
68. One bit time for the pseudorandom code is called a
69. What is the last amplifier stage of ______________ amplifier?
ANSWER: power amplifier
70. A submarine at greater depth can deploy a ______________ about 2.000 feet long, but 200 feet of it must float on the surface for proper reception
ANSWER: trailing wire antenna
Here is a listing of typical excess noise for various resistor types, given as RMS microvolts per volt applied across the resistor, measured over one decade of frequency:
71. The typical excess noise (flicker noise) for carbon resistor?
ANSWER: 0.1μV to 3.0 μV
72. The typical excess noise (flicker noise) for carbon film resistor?
ANSWER: 0.05 μV to 0.3 μV
73. The typical excess noise (flicker noise) for metal film resistor?
ANSWER: 0.02 μV to 0.2 μV
74. The typical excess noise (flicker noise) for wire-wound resistor?
ANSWER: 0.01 μV to 0.2μV
75. EDGE produces a 3-bit word for every change in carrier phase
76. Bit stuffing in the HDLC protocol works by transmitting on the sending side five consecutive 1’s from the body of the message and by inserting 0 before transmitting the next bit.
77. Magic T is also known as
ANSWER: hybrid T
78. It is the satellite component that senses the time or the incidence angle of solar radiation and provides electrical signal that may be used to compute the satellite orientation?
ANSWER: sun sensor
79. A few centimeters long solid insulated hook up wire that provides small capacitance to the ground that is adjusted during circuit alignment by bending slightly in one direction or another.
80. The maximum radiation for electronic equipment must not exceed ____________ mr/week
81. Radiation exposure rates produced by a TV receiver shall exceed ______________ milli roentgens per hour at a distance of 5 cm from any point on external surface of the receiver
82. What expresses the steepness of the skirts or the skirts selectivity of a radio receiver?
ANSWER: shape factor
83. Standard signal format of a numeric paging receiver
ANSWER: NEC D3 standard
84. The critical capacitance variation of most varactors used in frequency modulators
ANSWER: 12 to 1
85. If the satellite is launched at the speed of exceeding 25000 mph the satellite will not go in orbit and will break away from the gravitational pull of the earth and go out in deep space
ANSWER: space probe
86. What is the voltage of the local loop on hook?
ANSWER: -48 Vdc
87. In a propagation medium such in the glass of an optical fiber __________ is the scattering of the electromagnetic wave by particles with the size about equal or greater than the wavelength
ANSWER: MIE scattering
88. What LED is usual signal source for plastic fiber?
ANSWER: red LED
89. In color CRT, what refers to adjustment of the three electron beam so that each lens can phosphor dots on the appropriate color?
90. What is considered as the simplest transmitter keyed on and off to produce CW Morse code?
91. How many orbital planes which are equally spaced around the equator in GPS operational constellation?
92. What may cause ionic disturbance characterized by rapid cluttering sound hence voice communication is poor?
ANSWER: Aurora borealis
93. The mandatory 24 ship-to-shore communications from 1910 to 1912 was the establishment by the US Great Britain and other maritime nation as the direct result of the sinking of the 2 famous ships
ANSWER: The Republic and Titanic
94. When the called telephone is ringing , the Central Office sends a pulse AC voltage to the calling telephone. What is the signal called?
ANSWER: Ringback signal
95. What is the main accelerating element in CRT?
96. IN analog cellular system, the interfering signal strength remains approximately less than __ of desired signal strength to assure negligible interference
97. What is the approximate critical frequency of E layer?
ANSWER: 4 MHz
98. What is the approximate critical frequency of F 2layer?
ANSWER: 8 Mhz
99. The 10 base T Ethernet system is restricted only to __________.
100. What is the code used in 100 Mbps Tx Ethernet standard?
ANSWER: 3 level Manchester code
101. Principal musical intervals is considered dissonant
102. Cell site center that is mounted on a flat bed tractor used for emergency purposes
103. Geographic distance that is required between cells used in identical frequencies in order to avoid interference between the radio transmission of these cells
ANSWER: Distance to reuse ration D/R
104. Random data sent continuously by the NIC that disrupts the whole area network
105. Shifting of antenna pattern so that the major lobe is at angle below the horizontal
ANSWER: down tilt
106. Term used to describe ordinary voice telephony
ANSWER: Plain Old Telephone Service (POTS)
107. Time period for a single time slot in the GSM TDMA structure
108. The first note of the musical scale
ANSWER: Root note
109. In CATV system, what is the output RF terminal match?
ANSWER: 16 dB
110. Dielectric constant of polyethylene insulator
111. How much more feedpoint Z does a folded dipole have than a normal dipole?
ANSWER: 4 times
112. In TV system, if the 3.58 Mhz C amplifier in the receiver does not operate, the result will be __________.
ANSWER: No color
113. Allows users to access documents from widely separated sources of the internet using a common source
ANSWER: World Wide Web
114. What is the typical value of line turn around?
ANSWER: 1.5 ms
115. Which pulse in the V blanking corresponds to 3H lines wide?
ANSWER: V sync
116. F3 emission means carrier is frequency modulated by ____________.
117. How many horizontal lines are blanked out in the frame of TV receivers by V blanking
118. Which one is a non-continuous noise?
ANSWER: Impulse noise
119. What is the refresh rate in PAL
ANSWER: 50 Hz
120. BISYNC is found on what layer?
ANSWER: Data link layer