18-12 update

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18-12 update
2013-03-25 23:05:45

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  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?
  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.
  10. Energy contained in an object due to its position is ____ energy.
  11. What is the process by which an atom gains or loses electrons?
  12. What is a material that is good at allowing electricity to flow through it?
  13. What is defined as "extremely high resistance to the flow of electricity"?
  14. what is defined as "all matter between the extremes of conductors and insulators"?
  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"?
  18. This propagates in all directions
  19. This propagates in a specific direction while minimizing propagation in other directions
  20. Defined as "an antenna built for transmitting a certain signal is equally good at receiving that same signal"?
  21. This is defined as "the number of waves that pass a fixed place in a given amount of time"
  22. Time it takes for the completion, from any given point of a wave to the same point on the next wave.
  23. The distance between repeating units of a wave, usually measured in meters?
  24. Highest point of a wave
    Crest or peak
  25. Lowest point of a wave
  26. Defined as "height of a sine wave measured in peak or peak-to-peak"
  27. Defined as "movement through a medium"
  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"?
  30. Defined as "Radio wave bending as they move from one medium to another"?
  31. This is when a radio wave "bends" around an object.
  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.
  36. a positive ion has ___ than its normal amount of electrons.
  37. Defined as "the process by which an atom gains or loses its electrons".
  38. To generate voltage through magnetism what three things are needed?
    • Conductor
    • Magnetic field
    • relative motion
  39. Electromagnetic Waves is generated by __ power.
  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?
  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?
  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?

    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?
  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
  78. What is an undesired lower-power input signals that may be present at or near the frequency of the desired signal. 
  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
    Radio Repeater
  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
  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
    • Receiver
    • 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
    • Thuraya