# 18-12 update

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The flashcards below were created by user Rusty on FreezingBlue Flashcards.

1. What is defined as "Most widely used system of units, both in science & everyday commerce"
International System of Units (SI)
2. What is a decibel (dB) used for in relation to EW?
to express the ratio of two power levels.
3. Explain the SI prefix for each whole number.
• 1 trillion (1012) - Tera
• 1 billion (109) - Giga
• 1 Million (106) - Mega
• 1 Thousand (103) - Kilo
• .001 (10-3) - Mila
• .000001 (10-6) micro
• .000000001 (10-9) nano
• .000000000001 (10-12) Peca
4. What is the formula for determining the dB difference between two power ratios?
dB=(P2/P1)logx10
5. To effectively jam a signal what must the power be?
3 dB higher or 2x as strong
6. Name the 3 parts of an atom and their charges?
• Electron- negative charge
• Proton - Positive charge
• Neutron - no charge
7. What are the 6 methods to can create voltage?
• Fricton
• Magnetism
• Heat
• Pressure
• Light
• Chemical
8. What are the two forms of energy?
• Potential
• Kinetic
9. Energy contained in an object due to its motion is _____ energy.
Kinetic
10. Energy contained in an object due to its position is ____ energy.
Potential
11. What is the process by which an atom gains or loses electrons?
Ionization
12. What is a material that is good at allowing electricity to flow through it?
conductor
13. What is defined as "extremely high resistance to the flow of electricity"?
Insulator
14. what is defined as "all matter between the extremes of conductors and insulators"?
Semi-conductor
15. What does P,I,E and R represent on the Ohms law pie chart?
• P - Watts (power)
• I- Amps (current)
• E - Volts
• R - Ohms (Resistance)
16. In the formula dB = (P2/P1)log x 10 what does P1 and P2 represent?
• P1 = Target / Input
• P2 = Effect / Output
17. What is defined as "Determined by the direction of the lines of force making up the electric field"?
Polarization
18. This propagates in all directions
Omni-directional
19. This propagates in a specific direction while minimizing propagation in other directions
Directional
20. Defined as "an antenna built for transmitting a certain signal is equally good at receiving that same signal"?
Reciprocity
21. This is defined as "the number of waves that pass a fixed place in a given amount of time"
Frequency
22. Time it takes for the completion, from any given point of a wave to the same point on the next wave.
Cycle
23. The distance between repeating units of a wave, usually measured in meters?
Wavelength
24. Highest point of a wave
Crest or peak
25. Lowest point of a wave
Trough
26. Defined as "height of a sine wave measured in peak or peak-to-peak"
Amplitude
27. Defined as "movement through a medium"
Propagation
28. What are the three layers of the Earth's atmosphere?
• Troposphere (0-16 miles)
• Stratosphere (16-30)
• Ionosphere (30-300)
29. Defined as "Bouncing off on substance to extend the range of a radio wave"?
Reflection
30. Defined as "Radio wave bending as they move from one medium to another"?
Refraction
31. This is when a radio wave "bends" around an object.
Diffraction
32. What factors affect Ionosphere refraction?
• Density
• Frequency
• Angle
33. Explain the relationship between the wavelength and the frequency of the EM spectrum.
• Inversely Proportional
• High Freq = Short WL
• Low Freq = Long WL
34. SI is composed of what?
Base units and prefix
35. A negative ion has ____ than its normal amount of electrons.
more
36. a positive ion has ___ than its normal amount of electrons.
less
37. Defined as "the process by which an atom gains or loses its electrons".
Ionization
38. To generate voltage through magnetism what three things are needed?
• Conductor
• Magnetic field
• relative motion
39. Electromagnetic Waves is generated by __ power.
AC
40. Radio waves travel at what speed?
Speed of Light - 300,000,000 meters per sec
41. EM waves are what type of wave form?
Transverse Waves
42. Where is the stratosphere located and what effects does it have on radio waves?
Located between the troposhpere and ionosphere and has little to no effect.
43. The troposphere has what effect on radio waves?
Has a great affect on RW because of weather and temperature changes
44. Which layer contains four layers of electrically charged ions?
Ionosphere
45. What are the two principle RF transmitting methods?
Ground and Sky waves
46. What are some of the things that may affect the propagation of a radio wave?
mountains, hills, water towers, fences, other antennas, etc..
47. What type of transmission is used for long range OTH communications?
Sky wave, using refraction from the ionosphere
48. What are the layers of the Ionosphere during the day? Night?
• Day - D, E, F1, F2
• Night - F, E (F combine and D disappears)
49. What is a skip zone?
Zone of silence between ground waves and sky waves
50. What is usually the major loss of energy due to?
Spreading as the signal travels
51. What some examples of natural electromagnetic interference (EMI)?
Thunderstorms, snowstorms, cosmic sources, and the sun
52. What is meant by fading?
Variations in signal strength
53. What is the medium for EM waves?
Nothing, EM waves travel through a vacuum
54. What is ducting?
When a RW gets trapped between a tempature inversion
55. What type of current is typically used when forming a radio wave?
AC - Alternating current
56. When current is applied to a wire what happens?
An EM field builds around it
57. The EM or radiation field is made up of what?
An electric (E) field and a magnetic (H) field
58. Radio waves are expressed in terms of what?
Frequency, number of cycles per sec (hertz)
59. What is wavelength?
Physical length of one complete oscillation
60. What are the two primary types of polarization for radio waves?
Horizontal and vertical
61. What is the basic principle of coulombs law of charges?
The amount of attracting or repelling force between two objects is determined by the distance between them and their charges
62. Electric potential is measured by what?
Voltage
63. What is defined as "A circuit that has current flowing in both directions"?
AC circuit
64. What is true about current in a series circuit?
It remains constant throughout
65. What is wattage?
The measure of power
66. How much of a power difference is required to be effectively jamming?
3 dB
67. What are the three modes of Communication?

Explain
Simplex- signals flow in one direction

Half Duplex- flows in both direction but only one at a time

Full Duplex- flows in both direction simultaneously
68. What is the process of putting information on a carrier wave?
Modulation
69. What is a electro magnetic wave that can be modulated as in frequency, amplitude, or phase?
Carrier Wave
70. What is Amplitude Modulation?
radio signal in which the amplitude is varied to carry information from a transmitter to a receiver
71. What is Frequency Modulation?
radio signal in which the frequency is varied to carry information from a transmitter to a receiver
72. What is Phase Modulation?
electronic modulation in which the pahseis varied to transmit information contained in the signal.
73. What are three major classes of digital modulation techniques?
• Phase-shift keying (PSK)
• Amplitude-shift keying (ASK)
• Frequency-shift keying (FSK
74. What is a form of modulation which represents digital data as variations in the amplitude of a carrier wave.
Amplitude Shift key
75. What are the two common examples are Phase-shift keying (PSK)
binary phase-shift keying (BPSK) which uses two phases, and quadrature phase-shift keying (QPSK) which uses four phases
76. What is a form of frequency modulation in which the modulating signal shifts the output frequency between predetermined values?
Frequency-shift keying (FSK)
77. What is a signal or wave whose frequency is an integral (whole-number) multiple of the frequency of some reference signal or wave
Harmonic
78. What is an undesired lower-power input signals that may be present at or near the frequency of the desired signal.
Squelch
79. What is a combination of a radio receiver and a radio transmitter that receives a weak or low-level signal and retransmits it at a higher level or higher power, so that the signal can cover longer distances without degradation
80. What are the four major GSM frequencies that have become standard worldwide. They include GSM-900, GSM-1800, GSM-850, GSM-1900 and GSM-400.
GSM-850, GSM-900, GSM-1800, GSM-1900
81. What are the two network frequencies that are utilized to uplink and downlink the GSM network called?

What are they offset by?
Absloute radio frequency channel number

offset by 45 MHz
82. What are the four database elements of the Mobile Switching Center (MSC) are distributed to key sub-components that aid the MSC?
• Home Location Register (HLR)
• Visitor Location Register (VLR)
• Authentication Center (AuC)
• Equipment Identity Register (EIR)
83. WHat type of antenna is cheap and simple to make and typically operates with freqs of 12-50 MHz?
Yagi antenna
84. This antenna provides directional capabilities and is excellent for communications jamming.
Log-periodic Antenna
85. This antenna provides high gain and low side lobes levels and is mechanically cumbersome.
Corner Reflector Antenna
86. Thsi antenna allows wideband impedance and has a circularly polarized radiation field.
Helix antenna
87. What type of antenna is high gain reflector commonly used in TV, data links, and satellites communications?
Parabloic Antennas
88. This s the most popular omni-directional, half wave antenna
Dipoles
89. What four precise measurements can a radar provide?
• Range
• Bearing
• Height
• Speed
90. In relation to radar, what is the time the transmitter sends out RF energy?
Pulse width or pulse duration
91. In relation to radar, what is the beginning of one pulse to the beginning to another?
Pulse repetition Interval (PRI)
92. In relation to radar, what is the # of pulses per second a radar transmit?
Pulse Prepetition Frequency
93. In relation to radar, what is Beamwidth?
Horizontal or vertical thickness of a radar beam
94. Whats the ratio of the time the  transmitter operates to the time it could operate during a given transmission cycle?
Duty Cycle
95. Where does a radar have the most power and detection usually occurs?
Main Lobe
96. What is located directly opposite of the main lobe and has significant less sensitivity and signal strength.
Back Lobe
97. What is similar to the back lobe and adds another dimension to the radar pattern with sensitivity of 40-50 dBS?
Side lobe
98. What is the ability of a radar to display two targets flying at approximately the same range and azimuth with little altitude separation?
Elevation Resolution
99. What is the ability of a radar to display two targets flying at approximately the same range with little angular separation
Bearing (azimuth) resolution
100. What is the ability of a radar to separate two targets that are close together in  range  and  are  at  approximately  the  same  azimuth and is determined by pulse width.
Range Resolution
101. What are the primary components of a radar system?
• Transmitter
• Duplexer
• Antenna
• Display
102. What is the difference between active and passive jamming?
Active takes advantage of receiver sensitive and transmission to deny info to victim radar

Passive EM energy isn't transmitted
103. Explain Barrage and spot noise jamming.
Barrage sacrifices power for coverage and Spot raises the power to target frequency
104. What is a device that is designed to replicate similiar or better targets with electronic signatures?
A Decoy
105. What is the difference between an active decoy and a passive decoy?
• Active acts like a radar repeater which amplifies the signal and sends it back as a return,
• Passive  optimizes material to ensure EM energy is returned to enemy radars
106. What allows the base station to communicate with the moblie devices and is commonly referred to as the air interface?
UM interface
107. What are the three types of schemes utilized in the GSM network and explain?
• FDMA- one user gets his own ARFCN
• TDMA- user share ARFCN and is assigned a time slot
• CDMA- uses all fequencies and is assign a coding scheme
108. What two numbers can you find on a mobile device and what are they use for?
• IMEI-identify the mobile device
• IMSI-identify a subscriber
109. What is the primary limitation of frequency reuse in the GSM networks?
It cannot be reused if its shared by that of a neighboring cell
110. What part of the GSM network controls call handoff?
Base Station systems
111. What are the 2 basic components of a longe range cordless phone network?
• Handset
• base station
112. What are the primary satellite communications frequencies?
• L Band- 1525 thru1646.5 MHz
• C Band
• Ka Band
• Ku Band
113. What does a Thuraya user need IOT access the GSM networks?
A roaming agreementt between Thuraya and the provider
114. What are the three primary Satellite communications providers and which offers global coverage?
• Iridium----Global coverage
• INMARSAT
• Thuraya

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 Author: Rusty ID: 209478 Filename: 18-12 update Updated: 2013-03-26 03:05:45 Tags: update Folders: Description: 18 Show Answers:

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