Communications Engineering Coaching Materials: Section 5 Module 21

This is the Section 5 Module 21 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 21

QUESTIONS	ANSWER
1. Ratio of incident to transmitted radiation through a grid ratio of patient dose with and without grid	Bucky Factor
2. ECG recording requires a bandwidth of 0.05 to ______	100
3. Period during which the heart contracts	Systole
4. Who completes the development of first computed CT scanner in 1973	Hounsfield
5. Study of the response of an image receptor to x-rays	Sensitometry
6. Ratio of Radiographic contrast with a grid to that without a grid	Contrast Improvement Factor
7. Type of luminescence where the visible light is emitted only during the stimulation of phosphor	Fluorescence
8. A phenomenon caused by any support insulators used at the ends of the wire antenna	End effect
9. Process of converting an infinite number of possibilities to a finite number of conditions	Quantization
10. Which of the following is NOT a reason why most half wave antennas are mounted horizontally at low frequencies	More cost-effective
11. A 4-wire gigabit Ethernet implementation	1000 base T
12. Radiation doses in the range approximately 200 to 1000 rad produce the _____ syndrome	Hematologic
13. Modulation technique in which the frequency of the modulated signal varies with the amplitude of the modulating signal	AM
14. Highest layer in the hierarchy and is analogous to the general manager of the network by providing access to the OSI environment	Application layer
15. Handset is in cradle	On hook
16. Hartley’s law	I=kTB
17. A small variable capacitance in parallel with each section of ganged capacitor is called ____	Trimmer
18. Most commonly used digital modulation scheme	PCM
19. Form of redundancy error checking where each character has a numerical value assigned to it	Checksum
20. An 8 bit fixed length character set developed in 1962 by IBM	EBCDIC code
21. Analysis of persons irradiated therapeutically with superficial x-rays has shown that the skin erythema dose required to affect 50% of persons so irradiated is about ______ rad	600
22. Designed to send characters of the message with the specified bit rate without any fixed timing relationship from one character to the next	Asynchronous
23. Waveguide acts as a/an ____ filter	High pass
24. Data communication refers to the transmission of	All of the above (data, audio, voice)
25. Token Ring standard	802.5
26. Error correction scheme that actually detect and corrects transmission errors when they are received without requiring a retransmission	Forward error correction
27. A/an _______ is a range of frequency in which the upper frequency is double the lower frequency	Octave
28. Often used to compare the performance of one digital modulation technique to another	Bandwidth Efficiency
29. One complete revolution around a Smith Chart represents ___wavelength	½
30. At exactly one wavelength, the short circuited transmission line behaves as a/an _______ circuit	Parallel resonant
31. A mismatched transmission line is also referred to as a ___ line	Resonant
32. A flat conductor separated by an insulating dielectric from a large ground plane that is usually one quarter or one half wavelength long	Microstrip
33. How many wavelengths long are required for a pair of conductors to be considered as a transmission line	1/10 Lambda
34. Most common means of overcoming the problems of quantizing error and noise	Companding
35. The shape of the electromagnetic energy radiated from or received by an antenna is called the	Radiation pattern
36. Ratio of the speed of propagation on a line to that of light in free space	Velocity factor
37. This means that the characteristics and performance of an antenna are the same whether the antenna is radiating or intercepting an electromagnetic signal	Antenna reciprocity
38. Most widely used UTP cable that can carry baseband data at rates up to 100Mbps at a range up to 100m	CAT5
39. Used to lower the resonant frequency of a shortened vertical antenna	Top hat loading
40. Optical electronic device that measures the color concentration of a substance in solution	Colorimeter
41. Why DSB is not widely used	Signal is difficult to demodulate
42. Refers to the emission of electrons from a clean metallic surface when electromagnetic radiation falls onto that surface	Photoelectric effect
43. System wherein the input in a transmitter is a collector modulated	High level modulator
44. Recording of heart sounds	Phonocardiography
45. Unit of radiation exposure that will produce 2.08x10^9 ion pairs per cubic cm of air at STP	Roentgen
46. Recorder for measuring galvanic skin resistance	Electrodermograph
47. A digital process that allows several connections to share the high bandwidth of a link	TDM
48. Apparatus for measuring blood pressure	Sphygmomanometer
49. The government agency that regulates radio communications in the US	FCC
50. Antennas that transmit an equal amount of energy in the horizontal direction are called ___________	Omnidirectional
51. Circuit used to return the frequency response of a signal to its normal “flat” level	De-emphasis
52. The oldest microwave tube design which is commonly used in radar transmitters where they can generate peak power levels in the megawatt range	Magnetron
53. A quarter wavelength of coaxial or balanced transmission line of a specific impedance connected between a load and a source in order to match impedance is	Q section
54. The ability of an antenna to send or receive signals over a narrow horizontal directional range is referred to as ______	Directivity
55. Which antenna usually consist of two or more halfwave dipoles mounted end to end	Collinear
56. When the characteristic impedance of the transmission line matches the output impedance of the transmitter and the impedance of the antenna itself	Maximum power transfer will take place
57. An antenna made up of a driven element and one or more parasitic elements is generally referred to as _______	Yagi
58. Noise that is primarily caused by lightning, sometimes referred to as static noise	Atmospheric noise
59. A modulation process wherein both frequency and phase remains constant while the amplitude changes	ASK
60. Allows a wide variety of computers to share the same network	TCP/IP
61. A basic antenna connected to a transmission line plus one or more additional conductors that are not connected to the transmission line form a	Parasitic array
62. An antenna consisting of halfwave dipoles spaced from one another by one-half wavelength is the	Broadside array
63. Error correcting code used for correcting transmission errors in synchronous data streams	Hamming code
64. Horizontal frequencies for DTMF	1209 Hz, 1336 Hz, 1477Hz,1633Hz
65. Using DTMF, #8	852Hz and 1336 Hz
66. In DTMF, horizontal frequencies are also known as ______ frequencies	High group
67. In DTMF, vertical frequencies are also known as ______ frequencies	Low group
68. In PCM, it translates the quantized samples into digital code words	Encoder
69. An error detection technique in which a redundant bit is appended to every data unit so that the total number of 1’s in the unit (even the parity bit) becomes even	Vertical redundancy check
70. Reception of portions of a signal from one channel in another channel	Crosstalk
71. Type of digital modulation that uses two or more different output frequencies	FSK
73. Primary purpose is to serve as structural guideline for exchanging information between computers, workstations and network	OSI
74. A LAN topology in which the individual terminal, microcomputers or workstations are connected directly to a central computer	Star
75. Loss of data that occurs when two stations transmit on a network at the same time	Collision
76. A network topology in which data circulates from one computer to the next in sequence	Ring
77. Combination of amplitude and phase modulation	QAM
78. Means of transmitting data by shifting the phase angle of the transmitted signal	PSK
79. A microwave device that allows RF energy to pass through in one direction with very little loss, but absorbs RF power in the opposite direction	Isolator
80. Telephone switch that connects only to other switches and not to individual customers	Tandem office
81. A metal wrapped around the parabolic antenna aperture to eliminate sidelobes interfering nearby stations is called ______	Shroud
82. The wavelength of a wave in a waveguide	Is greater than in free space
83. The most common circuit used for demodulating binary FSK signal	PLL
84. Geostationary satellites are located at ______ with respect to the equator	0 degrees latitude
85. The quality of a space-link is measured in terms of _____ ratio	G/T
86. The nominal uplink frequency for the Ku-band	14 Ghz
87. The downlink frequency appear to vary by several kHz during a LEO satellite pass due to the change in the distance between the satellite and ground station, which is referred to as	Doppler effect
88. A satellite dish owner has a 3m dish designed for C band (4 Ghz) operation. The owner wants to use the same dish with a new feedhorn for Ku-band (12 Ghz) satellites. What effect will the change in frequency have on the gain and beamwidth of the antenna	Gain increases by9.54 dB, beamwidth decreases to 1/3 of its value
89. The most ambitious LEO constellation to date is	Teledesic
90. Antenna 1 has a gain of 5.3 dBi while antenna 2 has a gain of 4.5 dBd. Which of the following is true?	Antenna2 has a higher gain
91. Beamwidth is measured	Between half power points
92. A half-wave dipole is sometimes referred to as	Hertz antenna
93. An antenna can be matched to the feedline using	All of the above (shorted stub, LC network, loading coil)
94. “Ground Effect” refers to the effects on an antenna’s radiation pattern caused by	Radio signals reflecting off the ground
95. LPDA stands for	Log Periodic Dipole Array
96. As the length of a “long-wire” antenna increases	The number of lobes increases
97. A receiving antenna with a built-in preamplifier	Active antenna
98. Field strength at a distance from an antenna is measured with	Field strength meter
100. Cable used for local loops in telephone system is mainly	Twisted pair copper wires
101. Transmission from mobile unit to base station	Reverse link
102. The bandwidth of voice grade signals on a telephone system is restricted to	Allow signals to be multiplexed
103. The highest-ranking office in the DDD network in telephony in terms of the size of the geographical area served and the trunking options available	Regional center
104. AMPS	Advanced Mobile Phone Service
105. MSC	Mobile Switching Center
106. IMSI	International Mobile Subscriber Identification
107. BSC	Base Station Controller
108. In GSM, voice channels are called	Traffic
109. In Mobile Communications, GSM uses	Frequency hopping
110. An acoustical phenomenon wherein the sound continues to persist even after the cause of the sound has stopped resulting in repeated reflections is called _____	Reverberation
111. A type of microphone that uses the principle of a capacitor as a means of transduction. It uses a polarizing voltage of between 9 to 48V DC supply applied to its diaphragm by an external power supply	Condenser
112. A number from 0 to 1 representing the ability of a surface material to absorb sound energy	Absorption Coefficient
113. The difference in dB between the loudest level of sound and the softest passage of sound is known as	Dynamic range
114. Refers to the direction in space of electric vector of the electromagnetic wave radiated from an antenna and is parallel to the antenna itself	Polarization
115. Placing a metallic array on the antenna effects to increase the current at base of the antenna, and also to make the current distribution more uniform is called ________	Top Loading
116. What principle states that the properties of an antenna are independent of whether it is used for transmission or reception	Principle of reciprocity
117. Often used to cure the problem of great thickness required of lenses used at lower microwave frequencies	Zoning
118. A structure generally metallic and sometimes very complex, designed to provide an efficient coupling between space and the output of a transmitter or input to a receiver	Antenna
119. Any array that is directional at right angles to the plane of the array is said to have _____	Broadside action
120. The ratio of the focal length to the mouth diameter is called ________ of the parabola, just as in camera lense	Aperture

Complete List of Communications Engineering Coaching Materials

Communications Engineering Coaching Materials

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