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AT1 > Radar(2018) > Flashcards

Radar(2018) Flashcards

NAVEDTRA 14339

1
Q

What does the acronym radar mean?

A

Radio Detection and Ranging.

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2
Q

What is the speed of electromagnetic energy when it travels through air?

A

Approximately the speed of light or 186,000 statute miles per second.

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3
Q

What is the minimum range for a radar system with a pulsewidth of 10.5 s, which has a recovery time of 0.5 s?

A

1,804 yards.

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4
Q

What is the range of target when the elapsed time for the radar pulse to travel to the target and return is 370.8 microseconds?

A

30 nautical miles.

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5
Q

What factors determine the minimum range of a pulse radar system?

A

Thepulsewidthofthetransmittedpulseandtherecoverytimeoftheduplexerand the receiver.

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6
Q

The maximum range of a pulse radar system depends upon what three factors?

A

Transmitted power, pulse repetition frequency (PRF), and receiver sensitivity.

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7
Q

Define range resolution of a radar system.

A

Range resolution of a radar system is the minimum resolvable separation in range of two targets at the same bearing.

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8
Q

What effect is achieved by increasing the length of a pulsewidth?

A

The longer the pulsewidth, the greater the range capabilities of the radar.

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9
Q

What term is used to describe the situation in which atmospheric temperature first in- creases with altitude and then begins to decrease?

A

Temperature inversion.

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10
Q

The bending of radar waves due to a change in density of the medium through which they are passing is known by what term?

A

Refraction.

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11
Q

A very high radar antenna indicates what type of frequency?

A

A low carrier frequency.

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12
Q

Radar frequency ranges are divided into sections referred to by what term?

A

Bands.

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13
Q

The ideal radar pulse shape should have what characteristics?

A

A square wave with very sharp leading and trailing edges.

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14
Q

What part of a radar pulse affects its range accuracy?

A

The leading edge.

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15
Q

What is the reciprocal of PRF?

A

PRT

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16
Q

What two RF generating devices have low interelectrode capacitance, low transit time, and the ability to handle very high levels of RF power?

A

Magnetron and klystron.

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17
Q

What is the duty cycle of a radar system that has an average power of 2 Megawatts and a peak power of 200 Megawatts?

A

0.01.

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18
Q

What radar transmission method does not depend on target motion or relative frequency of the returned signal?

A

Pulse modulation radar.

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19
Q

What is the purpose of radar synchronizer?

A

Provides proper timing pulses to components of the radar system.

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20
Q

What are the two synchronization classifications for a basic pulse radar system?

A

Self-synchronized or externally synchronized.

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21
Q

What are the two high-powered RF generators used in transmitters of pulse radar systems?

A

Magnetron and klystron.

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22
Q

Adding additional intermediate cavities between the input and output of a klystron has what affect on power output?

A

An increase in the power available at the output.

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23
Q

What is a duplexer and what is its purpose in a radar system?

A

An electronic switch that permits the use of one antenna for both transmit and receive functions.

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24
Q

What type of receiver mixes incoming signals with the receiver’s local oscillator signal to produce an intermediate frequency?

A

Superheterodyne.

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25
Q

What is the purpose of the AFC circuitry within the receiver?

A

To maintain a constant IF frequency out of signal mixer.

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26
Q

What function does the detector perform within the receiver?

A

Converts IF pulses into video pulses, which are applied to radar indicators.

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27
Q

What are the three types of radar indicators?

A

PPI, RHI, and A-scope.

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28
Q

The PPI provides what type of presentation?

A

A map-like presentation of the region scanned.

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29
Q

What are the nine major components that make up a typical pulse radar system?

A

Antenna, antenna servo system, duplexer, transmitter, receiver, modulator, power supplies, synchronizer, and indicator

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30
Q

What are the four positions on the SCAN SPD rotary switch on the C-10535/APS-130 Radar Set Control?

A

OFF, 25, 50, 100.

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31
Q

What are the four functional groups of the T-1396/APS-130 Transmitter?

A

Power supply group, modulator group, transmitter group, and BIT group.

32
Q

What position is the DVRI located in?

A

ECMO 1.

33
Q

The CV-2434 Analog-Digital Converter is a major component of what radar system?

A

The APS-130.

34
Q

During update mode, what slew control has priority for all inputs?

A

ECMO 1.

35
Q

The acronym radar is derived from what words?

A

Radio, detection, and ranging

36
Q

Radar uses what form of energy to detect the presence of objects?

A

Electromagnetic energy

37
Q

RF energy travels through air at approximately what speed?

A

186,000 statute miles per second
162,000 nautical miles per second
300 million meters per second

38
Q

What is the time required for two-way travel of an RF pulse if the target is 15 miles from the radar unit?

A

185.4 μs

39
Q

An increase in recovery time of a radar set will cause which of the following results?

A

Increase in minimum range and decrease in receiver sensitivity

40
Q

A radar set has a pulsewidth of 3 μs. In order for the operator to see two separate blips that are directly on the same line of bearing, what minimum distance must separate the targets?

A

492 yards

41
Q

Apulse radar’s range resolution is a function of the transmitted pulsewidth, while azimuth resolution is a function of what?

A

Antenna beamwidth

42
Q

In order for two targets at the same range to appear as two targets instead of one target on the radar’s indicator, what minimum distance must separate the two targets?

A

One beamwidth

43
Q

The maximum power of a RF transmitted pulse is referred to by what term?

A

Peak power

44
Q

Radar performance is affected by which of the following factors?

A
  • Prevailing atmospheric conditions
  • The quality of maintenance performed on the equipment
  • The operator’s knowledge of the equipment’s capability
45
Q

Although high-frequency energy from a transmitter travels essentially in a straight line and a constant speed, refraction and speed change are known to occur. Which of the following atmospheric conditions cause this to happen?

A

Temperature, pressure, and vapor content

46
Q

Which of the following conditions is formed by a temperature inversion and/or by a moisture lapse that may extend or reduce the range of radar?

A

Ducting

47
Q

The elapsed time between the start of one transmitted pulse and the start of the next is known as which of the following terms?

A

PRT

48
Q

In addition to certain power considerations, the output pulse of a radar transmitter should possess which of the following characteristic shapes in order to present nearby targets on an indicator?

A

Narrow with a sloping trailing edge

49
Q

Generally, the maximum range of pulse type radar is determined by what element

A

Pulse repetition frequency

50
Q

The PRF of a radar must be low enough to eliminate ambiguous targets, but high enough that the antenna’s speed of rotation does not interfere with what factor?

A

The transmitted frequency

51
Q

A radar set with a PRF of 2,000 PPS and an antenna rotation of 20 rpm produces what maximum number of pulses per degree?

A

16.6

52
Q

Which of the following statements is correct concerning peak power and average power of a pulsed radar system?

A

Peak power is expended during the transmission of a pulse, and average power is the power expended over the pulse repetition time

53
Q

Which of the following formulas expresses the duty cycle of a radar set?

A

PW x PRF

54
Q

Which of the following methods of transmitting RF energy uses the Doppler principle for radar detection?

A

Continuous-wave

55
Q

Frequency-modulated radars transmit a wave that is continuously varying from a fixed reference frequency. When frequency modulation is used, how is the target detected?

A

Comparing the frequency of the signal that
is presently being transmitted with the
received frequency that has been reflected
from the target

56
Q

Continuous-wave radar, which employs the Doppler effect, is best suited in detecting which of the following targets?

A

Targets with a high degree of bearing resolution

57
Q

Which of the following components of a radar system determines the timing for all components of the radar?

A

Synchronizer

58
Q

What is the purpose of the modulator in a typical pulse radar system?

A

To supply high voltage, rectangular pulses

to drive the transmitter

59
Q

What modulator circuitry determines the voltage level and width of the pulse generated?

A

The pulse forming network

60
Q

Which of the following tubes should be used as the power amplifier in a radar transmitter?

A

Klystron

61
Q

The process whereby some electrons are accelerated, some are decelerated, and others are unaffected in the movement of the electron beam towards the collector end of a klystron is referred to by what term?

A

Bunching

62
Q

What is the primary function of radar duplexing system?

A

To permit the use of one antenna for

transmission and reception

63
Q

A defective duplexer will likely cause damage to which of the following radar components?

A

The receiver

64
Q

Because of the difficulty in amplifying high-frequency signals received in most radar receivers, it is necessary to generate an intermediate-frequency signal by a process referred to by which of the following terms?

A

Heterodyning

65
Q

The Azimuth Elevation Range Indicator IP-1060A/APQ-148 is located at what station?

A

ECMO 1

66
Q

How many slew controls are there with the APS-130 radar system?

A

2

67
Q

What are the four ranges on the PPI RNG rotary switch on the RCP?

A

15, 30, 75, 150

68
Q

The Radar Set Control C-10535/APS-130 (RCP) is located at which of the following stations?

A

ECMO 1

69
Q

The intermediate frequency is produced in what stage of a microwave receiver?

A

Signal mixer

70
Q

What section of a radar receiver usually determines the overall bandwidth?

A

IF amplifier/detector

71
Q

The IF amplifier stages of a radar receiver determines which of the following receiver characteristics?

A
  • The gain
  • Signal-to-noise ratio
  • Converts IF pulses to video pulses
72
Q

Which of the following radar displays provides a map-like presentation that is practically an exact replica of the region scanned by the radar antenna?

A

PPI

73
Q

On a RHI display, what is represented by the vertical axis?

A

Elevation

74
Q

On an A-scope presentation, what is displayed on the horizontal axis?

A

Range only

75
Q

Which component provides a crystalcontrolled clock and digital timing loop to generate PRF trigger, sweep triggers, range markers, and precision range line signal?

A

RSG

AT1 (31 decks)

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