# 1812 WOBC -Follow On Classs

The flashcards below were created by user 1812WOBC 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?
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
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 is "the variation of a property of an EM wave or signal, such as amplitude, frequency, or phase"?
Modulation
68. An EM wave that can be modulated as in frequency, amplitude, or phase, to transmit speech, music, images, or other signals.
Carrier wave
69. A type of radio signal in which the amplitude, or strength of a radio wave is varied in order to carry info from a transmitter to a receiver.
Amplitude Modulation
70. Radio signal which freq of the radio wave is varied to carry information from transmitter to the receiver.
Frequency Modulation
71. Electronic modulation in which the phase of a carrier wave is varied in order to transmit the signal.
Phase Modulation
72. Modulation in which the amplitude, duration, position, or mere presence of a discrete pulse maybe so controlled as to represent the message to be communicated.
Pulse Modulation
73. The range of the EM spectrum located either above or below the freq of a carrier signal.
Sidebands
74. _____ is an integer multiple (exact whole #) of a fundamental frequency.
Harmonic
75. Excludes undesired lower-power input signals that maybe present at or near the frequency of desired signal.
Squelch
76. A combination of radio receiver and transmitter. Receives weak or low-level signal and retransmits it at a higher level.
77. Digital data is represented as variations in the amplitude of a carrier wave.
78. Shifts the output frequency between predetermined values to signify data.
FSK Frequency Shift Key
79. Phase is changed to represent data. Two common types are Binary Quadrate.
Phase Shift Key PSK
80. What three factors affect the radiation pattern of a transmitted signal?
• Antenna Configuation
• Application
• Surrounding Terrain
81. What type of antenna is cheap and simple to make. Typically operates within what frequencies?
• Yagi Antenna
• 12-50 MHz
82. What type of antenna provides directional capability and excellent for jamming?
Log-Periodic Antenna
83. This antenna allows for wideband impedance and has a circularly polarized radiation field.
Helix Antenna
84. Provides a high gain  and low side lobe levels, mechanically cumbersome.
Corner Reflect Antenna
85. What type is high gain reflector commonly used in TV, data links and satellite comms?
Parabolic Antenna
86. Most popular omni-directional, half wave antenna.
Dipoles
87. What are the four measurements radar can provide?
• Range
• Bearing
• Height
• Speed
88. Defined as "Time transmitter is sending out RF energy"
Pulse Width (PW) or Pulse Duration (PD)
89. Defined as "Beginning of one pulse to the beginning of the next pulse; measured in milliseconds.
Pulse Repetition Interval (PRI)
90. Number of pulses per second the Radar transmits is called what?
Pulse repetition Frequency (PRF)
91. What is "the horizontal and vertical thickness of the Radar beam?
Beamwidth
92. What is "The ratio of the time the transmitter operates to the time it could operate during a given transmission cycle"?
Duty Cycle
93. This is where Radar has most power and where target direction usually occurs.
Main Lobe
94. Directly opposite of the main lobe, significantly less power than main lobe.
Back Lobe
95. Side of main lobe; 40-50 dB below main lobe.
Side Lobe
96. Round trip time for RF wave to travel to and from target 1 nautical mile away.
97. Maximum range a Radar can detect a target due to the curvature of the Earth.
98. Radar's ability to distinguish two targets at similar elevation? Similar Range? and Minimum Separation?
• Elevation Resolution
• Range Resolution
• Bearing (Azimuth) Resolution
99. What are the primary components of a radar system?
• Transmitter
• Duplexer
• Antenna
• Display
100. Create confusion & deny critical information to negate the effectiveness of EN radar is what?
101. Purpose is to interfere with EN ability to pass information over link.
Communications Jamming
102. What is the basic approach to jamming a digital signal?
Create bit errors 1/3 of the time.
103. In Radar jamming what is the point when the jammer gets so close to the receiver that the jamming to signal ratio is less than one?
Burn-through range
104. In a GSM network the two frequencies utilized for the uplink and downlink are called what and offset by what?
• Absolute Radio Frequency Channel Number
• (ARFCN)
• 45 MHz
105. What are the four primary GSM bands
• GSM 850
• GSM 900
• GSM 1800
• GSM 1900
106. What four databases are used by the Mobile Switching Center (MSC)?
• Home Location Registrar (HLR)
• Visitor Location Registrar (VLR)
• Equipment Identity Registrar (EIR)
• Authentication Center (AuC)
107. This allows base station to communicate with the mobile device and is commonly referred to as the air interface.
Um Interface
108. What are the three types of cellular access schemes used by the GSM network?
• FDMP
• TDMA
• CDMA
109. What two numbers are found on a cellular phone?
• International mobile equipment identity
• (IMEI)
• International Mobile Subscriber Identity
• (IMSI)
110. What is the primary limitation of frequency reuse in the GSM network?
A freq can't be reused if it is shared by that of a neighboring cell.
111. What part of the GSM network controls call handoffs?
Base Station System BSC
112. What are the basic components of a LRCP network?
• Hand Set
• Hand Set Base Station
113. What are the primary satellite communication frequencies?
• L Band (1525-1646.5 MHz) for traffic
• C, Ka, Ku, for control coms and control channels
114. What does a Thuraya need in order to access the GSM network?
A roaming agreement between Thuraya and the provider
115. What are the three primary Satellite communications providers? Which is total global?
• Iridium <--Global
• Inmarsat
• Thuraya
 Author: 1812WOBC ID: 209186 Card Set: 1812 WOBC -Follow On Classs Updated: 2013-03-26 01:49:04 Tags: Follow Class Folders: Description: Follow on Class Show Answers: