Module 18

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bugsbunny2255
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193099
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Module 18
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2013-01-31 02:46:59
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AT2 Adv
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  1. Radar uses what form of energy to detect ships, planes, and land masses?
    Electromagnetic energy
  2. What radar measurement of an object is referenced to true north?
    Surface angle
  3. The elevation angle to the target is the angle between which of the following references?
    Horizontal plane and line of sight
  4. Electromagnetic energy travels through air at approximately what speed?
    • 984 feet per microsecond
    • 186,000 statute miles per second
    • 162,000 nautical miles per second
  5. For an object that is detected 15 miles from a radar set, what is the approximate time required for the rf energy to travel to and return from the object?
    185 microseconds RANGE = EL. TIME / 12.36 mS per NM
  6. Of radar characteristics,which has NO effect on maximum range capability?
    Recovery time
  7. Which characteristic of radar system determines the degree to which the radiated energy is affected by atmospheric conditions?
    Carrier frequency
  8. Pulse-repetition time is described as the
    period of time from the beginning of one transmitter pulse to the beginning of the next
  9. Which term describe radar returns that exceed the prt of the radar?
    Ambiguous
  10. What type of transmitter power is measured over a period of time?
    Average
  11. Which formula can be used to compute the duty cycle of a radar set?
    pw/prt
  12. The relative bearing of a radar echo is measured with respect to which reference points?
    Centerline of your own ship
  13. Altitude- or height-finding radar systems require a beam with which characteristic?
    Narrow in the vertical plane
  14. Target resolution is the ability of a radar to distinguish between targets that are at nearly the same range and/or bearing.Range resolution is dependent on which factor?
    Pulse width and target size
  15. The width of a radar beam and range to a detected object are the determining factors in which radar system characteristic?
    Bearing resolution
  16. Radar uses what form of energy to detect ships, planes, and land masses?
    Electromagnetic energy
  17. What radar measurement of an object is referenced to true north?
    Surface angle
  18. The elevation angle to the target is the angle between which of the following references?
    Horizontal plane and line of sight
  19. Electromagnetic energy travels through air at approximately what speed?
    • 984 feet per microsecond
    • 186,000 statute miles per second
    • 162,000 nautical miles per second
  20. For an object that is detected 15 miles from a radar set, what is the approximate time required for the rf energy to travel to and return from the object?
    185 microseconds
  21. Of the following radar characteristics,which has NO effect on maximum range capability?
    Recovery time
  22. Which of the following characteristics of a radar system determines the degree to which the radiated energy is affected by atmospheric conditions?
    Carrier frequency
  23. Pulse-repetition time is described as the
    period of time from the beginning of one transmitter pulse to the beginning of the next
  24. Which of the following terms describes radar returns that exceed the prt of the radar?
    Ambiguous
  25. What type of transmitter power is measured over a period of time?
    Average
  26. Which of the following formulas can be used to compute the duty cycle of a radar set?
    pw/prt
  27. The relative bearing of a radar echo is measured with respect to which of the following reference points?
    Centerline of your own ship
  28. Target resolution is the ability of a radar to distinguish between targets that are at nearly the same range and/or bearing.Range resolution is dependent on which of the following factors?
    Pulse width and target size
  29. What is the approximate range resolution(in yards) of a radar set with a pulse width of 15 microseconds and a peak power of 2 kilowatts?
    2460 PW X 164 YDS per sec.
  30. The width of a radar beam and range to a detected object are the determining factors in which of the following radar system characteristics?
    Bearing resolution
  31. Which of the following factors has/have the greatest effect on the accuracy of a pulse radar?
    Resolution
  32. Refractions and speed changes are known to occur in electromagnetic wavefronts. These phenomena are caused by which of the following conditions?
    Temperature, Vapor content, and Atmospheric pressure
  33. Temperature inversions and/or moisture lapses in the atmosphere may extend or reduce the range of a radar by creating
    ducts
  34. In a pulse radar system, which of the following components should you expect to find?
    • Synchronizer and transmitter
    • Duplexer and antenna system
    • Receiver and indicator
  35. In a pulse radar system, what component controls timing throughout the system?
    Synchronizer
  36. What component of the transmitter supplies the trigger pulse, which acts as a switch to turn the klystron on and off?
    Modulator
  37. Which of the following radar components allows the use of one antenna for both transmitting and receiving radar energy?
    Duplexer
  38. The sweep frequency of a radar indicator is determined by what parameter of the radar system?
    Pulse-repetition frequency
  39. The type and method of scanning used by a radar system depend upon which of the following radar system design considerations?
    • Antenna size
    • Type of radar
    • Purpose of the radar
  40. In a single stationary-lobe scanning system, complete azimuth coverage is achieved by which of the following methods?
    A continuously rotating antenna
  41. Which of the following methods can be used to achieve radar-beam scanning?
    • Mechanical
    • Electronic
    • Combined mechanical and electronic
  42. In a conical-scan antenna, nutation of the radar beam is usually accomplished by which of the following methods?
    By moving the reflector
  43. At any given distance from the antenna,the radar beam axis of a conical-scan antenna follows what pattern?
    A circle around the scan axis
  44. In a monopulse scanning radar, the relative position of a target with respect to the radar-beam axis is determined by comparing which of the following signal components?
    The amplitudes of the returning rf energy in each horn
  45. In a monopulse scanning system, which of the following feedhorn signal combinations makes up the bearing signal?
    (A + C) - (B + D)
  46. In a monopulse scanning system, which of the following combinations make up the range signal?
    A + B + C + D
  47. Monopulse receivers use what signal as a phase reference?
    Range
  48. In the cw radar transmission method, the Doppler effect provides which of the following target information?
    • Speed of the target
    • Presence of the target
  49. The frequency of the returned signal increases when a target is approaching and decreases when a target is moving away in which of the following types of radar systems?
    Doppler
  50. Continuous-wave radar that uses the Doppler effect is best used in detecting which of the following types of targets?
    Past-moving or Fast moving
  51. Range information can be obtained in a Doppler radar by which of the following methods?
    • Sweeping the transmitter frequency
    • Using two separate transmitters
  52. Frequency-modulated radars transmit a wave that continuously changes infrequency about a center frequency.Using frequency modulation, the range to a target is determined by using which of the following methods?
    By comparing the frequency of the transmitted signal with the returned frequency from the target
  53. Which of the following statements describes the advantage of using pulse modulation (pm) rather than continuous wave(cw) in a radar system?
    Pm does not depend on target motion; cw does
  54. In Doppler radar, some definite relationship must exist between the transmitted frequency and the reference frequency. For what purpose is this relationship used?
    To detect the Doppler shift of the received signal
  55. Which of the following JETDS (Joint Service Classification System) classifications identifies a shipboard fire control radar set?
    AN/SPG-55
  56. For most military applications, which of the following radar systems is/are used?
    Both track and search radars are used
  57. Detection of surface and low-altitude air targets is the primary purpose of which of the following types of radar?
    Surface search
  58. Which of the following are typical characteristics of surface-search radars?
    • High pulse-repetition rates
    • Narrow pulse widths
    • High frequencies
  59. Long-range aircraft detection is provided by which of the following types of radar?
    Air search
  60. Which of the following are characteristics of a typical air-search radar?
    Low frequency
  61. Which of the following types of radar provides accurate range, bearing, and altitude of aircraft?
    Height-finding
  62. Which of the following radars would most likely be used to direct CAP aircraft during an intercept?
    Three-coordinate radar
  63. The range capability of a 3D radar is limited by which of the following characteristics?
    High operating frequency
  64. Fire control radars must be directed to the general location of a desired target.This is because of which of the following characteristics?
    Narrow beam pattern
  65. When a fire-control radar antenna approaches the general direction of a target, the radar enters which of the following modes of operation?
    Acquisition
  66. Which of the following characteristics is/are typical of a fire-control radar?
    • Very high prf
    • Very narrow pw
    • Very narrow beam
  67. Complete control of a beam-rider missile requires what minimum number of radar beams?
    3
  68. Which of the following circuits converts square waves to positive and negative triggers?
    A short-time-constant RC differentiator
  69. Which of the following circuits is used to remove either the negative or positive triggers from the output of a sine-wave oscillator?
    A limiter
  70. When the master oscillator in a multivibrator timer is asymmetrical, the output of the master oscillator is in the form of
    rectangular waves
  71. The positive and negative output pulses of the a stable multivibrator are sent to the indicator for which of the following purposes?
    • To intensify the crt beam
    • To gate the range-marker generator
  72. Which of the following oscillators generates sharp trigger pulses without additional circuitry?
    Single-swing blocking oscillator
  73. A radar transmitter is triggered directly by high voltage pulses from what unit?
    The modulator
  74. The peak power of a transmitted rf pulse depends on which of the following factors?
    Amplitude of the modulator pulse
  75. The transmitter range timing circuit must be triggered at the instant the transmitted pulse leaves the transmitter. For which of the following reasons is this timing so important?
    To ensure accurate range
  76. For proper operation of the magnetron,the modulator pulse must have which of the following characteristics?
    • A flat top
    • A steep leading edge
    • A steep trailing edge
  77. In order that nearby targets may be detected, which of the following characteristics must the transmitted pulse have?
    A steep trailing edge
  78. Compared to the hard-tube modulator,the line-pulsing modulator has which of the following advantages?
    It is more efficient
  79. The modulator of a radar basically consists of a power supply, a switch, a storage element, and a/an
    charging impedance
  80. Which of the following devices can be used as the storage element in a radar modulator?
    A capacitor
  81. A signal introduced at the input end of an artificial transmission line moves through the circuit to the output end and is reflected back to the input. The output end of an artificial transmission line appears to the input signal as what type of circuit?
    Open
  82. The discharge pulse from the artificial transmission line causes a voltage of what magnitude to appear across the primary of the pulse transformer?
    One-half the original charge voltage
  83. What parameter, if any, of the output pulse from an artificial transmission line is affected by the inductance and capacitance of each section of the line?
    Width
  84. A pulse-forming network exhibits electrical behavior similar to which of the following devices?
    An artificial transmission line
  85. The requirements of a modulator switch are to (1) reach full conduction quickly,(2) consume low power, (3) start and stop conduction suddenly, and (4)conduct high currents and handle high voltages. Which of the following tubes meets these requirements?
    A thyratron
  86. What modulator circuit characteristic determines the charging rate of the storage element?
    Charging impedance
  87. Which of the following types of instability are common to magnetron oscillators?
    • Mode skipping
    • Mode shifting
  88. Which of the following magnetron characteristics can be caused by low magnetic field strength?
    • Low power output
    • Excessive plate current
    • Incorrect operating frequency
  89. Which of the following maximum tuning ranges is typical for a tunable magnetron?
    ±5 percent around the center frequency
  90. Compared to the keyed-oscillator transmitter, power-amplifier transmitters are used more often with mti radar systems because power-amplifier transmitters provide
    better stability
  91. Which of the following tubes should be used as the power amplifier in a radar transmitter?
    The magnetron
  92. Which of the following components determines the pulse width of a power amplifier transmitter?
    The modulator
  93. The intermediate stages of a power amplifier transmitter have operating power only during which of the following times?
    During the time the modulator pulse is applied
  94.  Using a frequency synthesizer instead of a heterodyning mixer as the frequency generating source for a power-amplifier transmitter is an advantage because the frequency synthesizer
    produces discrete frequencies over a wide band
  95. Unwanted oscillations in an rf amplifier transmitter are prevented because of which of the following pulse relationships?
    The rf pulse is wider than the modulator pulse
  96. A power-amplifier transmitter that transmits a broad band of frequencies typically uses which of the following tubes as the final stage?
    A crossed-field amplifier
  97. What is the primary function of the radar duplexing system?
    To permit the use of one antenna for transmission and reception
  98. The direct-coupled waveguide duplexer is connected to the waveguide at the location of
    maximum magnetic field intensity
  99. In a hybrid-ring duplexer, the fields at the entrance of an arm must have what phase relationship to propagate energy down the arm?
    180 degrees
  100. The maximum range at which a radar receiver can detect an object is limited by which of the following factors?
    Noise
  101. An effective radar receiver should have again factor that is in which of the following ranges?
    106 to 108
  102. An over driven amplifier stage in a receiver may cause which of the following conditions?
    Blocking
  103. The intermediate frequency is produced in what stage of a microwave receiver?
    The mixer
  104. What section of a radar receiver usually determines the overall bandwidth?
    The IF amplifier
  105. What component in a receiver afc circuit produces an output voltage proportional in amplitude and polarity to any change in the intermediate frequency?
    The discriminator
  106. An efficient local oscillator must have which of the following characteristics?
    • Tunable frequency
    • Stable output frequency
    • Operation in the 4,000 megahertz range
  107. Which of the following devices would be used as a local oscillator in a radar receiver?
    A reflex klystron
  108. Which of the following advantages is gained by using a crystal mixer in a microwave receiver?
    Less noise
  109. The resonant circuit at the output of an unbalanced crystal mixer serves which of the following purposes?
    It eliminates unwanted signals
  110. The balanced transformer connected to the crystals of a balanced mixer has a secondary that is tuned to what frequency?
    The desired IF
  111. The IF amplifier stage of a radar receiver determines which of the following receiver characteristics?
    • The gain
    • The effective bandwidth
    • The signal-to-noise ratio
  112. The detector in a radar receiver converts the IF pulses into what form?
    Video pulses
  113. Agc automatically adjusts the gain of the receiver by controlling which of the following quantities?
    IF amplifier bias
  114. A radar receiver uses iagc for which of the following purposes?
    • To reduce the amplitude of echoes from distant targets
    • To prevent full amplification of strong signals
  115. The primary function of the mti system is to display which of the following types of targets?
    Moving targets only
  116. Delaying the received signals in the mti system permits them to be combined with the next set of received signals so that only desired signals are displayed.The signals displayed are formed by which of the following methods?
    Subtraction
  117. In the mti system, what is the purpose of the coho lock pulse?
    To synchronize the coho and transmitted frequency phase relationship
  118. The amplitude of coherent video is determined by the phase difference between which of the following signals?
    Coho reference and IF echo
  119. The lin-log amplifier provides (a) a linear output voltage for what amplitude of input signal and (b) a logarithmic output voltage for what amplitude of input signal?
    Low and high
  120. What channel in a monopulse receiver is used as the reference channel?
    Range
  121. Which of the following units of a radar system determines timing for all units of the radar?
    Synchronizer
  122. Which of the following classifications describes a radar system that uses a master oscillator to produce timing pulses?
    Externally synchronized
  123. Which of the following oscillators maybe used as the master oscillator in a radar system?
    • A stable multivibrator
    • Sine-wave oscillator
    • Blocking oscillator
  124. Which of the following oscillators, used in a synchronizer to provide timing trigger pulses, does NOT require a pulse shaping circuit in its output?
    Blocking oscillator
  125. A radar system in which timing triggers are determined by the pulse-repetition rate of the modulator uses what type of synchronization?
    Self-Synchronized
  126. Which of the following radar indicator functions is/are controlled by gate pulses from the synchronizer?
    • Sweep duration
    • Sweep initiation
    • Range-mark generator gating
  127. Indicator sweep voltage in a radar is normally initiated at which of the following times?
    At the same time as the transmitter trigger
  128. The fly back retrace of a radar system indicator is prevented from appearing on the cathode-ray tube by removing the
    positive-intensity gate pulse applied to the control grid
  129. Which of the following characteristics is NOT a requirement of a basic radar system timing circuit?
    It must develop random frequencies

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