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FAA Radar Concepts > Module 3 > Flashcards

Module 3 Flashcards

1
Q

The _______ determines the design of the transmitter.

A

final power amplifier (FPA)

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2
Q

A properly functioning radar system should be able to accurately reproduce a rectangular pulse. T/F

A

True

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3
Q

what is the waveform obtained when the DC pulse amplitude is plotted as a function of time, such as on an oscilloscope.

A

Pulse Shape

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4
Q

What is the energy of the pulse calculated by multiplying the pulse voltage and the pulse current.

A

Pulse Power

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5
Q

What is the power which would equal the power delivered during the pulse if power were delivered at a steady rate throughout one complete pulse interval

A

Average Power Output

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6
Q

What is the number of times per second that the pulse repeats, as controlled by the synchronizer. It is expressed in Hz, and can be calculated by taking the inverse on the pulse repetition time

A

Pulse Repetition Frequency

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7
Q

What is the ratio of the pulse width (tp) to pulse repetition time (PRT), as expressed as a fraction or a percentage.

A

Duty Ratio

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8
Q

What is the process of ensuring that the impedance of the modulator components equals that of the FPA components. If there is an impedance mismatch between the modulator and the FPA, energy will be reflected back to the source.

A

Impedance Matching

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9
Q

The main difference between a solid-state FPA and a tube type FPA is that the solid-state FPA _____.

A

lacks the ability to amplify in the range of megawatts

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10
Q

A stationary target may be perceived as a moving target if the amplitudes of the transmit pulses vary. T/F

A

True

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11
Q

The radar with the longest listening period is the _____

A

ARSR-4

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12
Q

Transmitter design depends upon the construction of the _____.

A

FPA (Final Power Amplifier)

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13
Q

RF signals undergo _____ shaping in the RF section of an ASR-8/9

A

Final

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14
Q

The FPA receives _____ power from the modulator section

A

High Voltage DC Power

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15
Q

The PFN (Pulse Forming Network) is also called _____

A

Energy Storage Device

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16
Q

The DC power supply section in a solid-state transmitter provides _____ voltage, _____ current power to the transmitter’s RF drivers and power amplifier modules.

A

Low High

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17
Q

The _____ is inhibited during transmission to prevent recharging

A

DC Power Suppily

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18
Q

Why must a transmitter’s input remain stable

A

To prevent displaying moving targets as fixed ones

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19
Q

Which input must remain stable to ensure stable FPA outputs

A

Coherent oscillator

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20
Q

A trigger from the _______ controls a charge/discharge switch in the modulator

A

synchronizer

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21
Q

A crowbar circuit is used in a(n) _____ to protect the load

A

active-switch modulator

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22
Q

The PFN (Pulse Forming Network) is also known as the _______.

A

energy storage device

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23
Q

The _____ provides isolation between the energy storage device and the HVPS (High Voltage Power Suppily).

A

charging circuit

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24
Q

The _____ must be biased on to allow energy to flow through it

A

SCR (Silicone Controlled Rectifier)

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25
Q

_____ circuits retain DC pulse power.

A

Diode

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26
Q

The modulator delivers high-powered DC pulses to the _____.

A

FPA (Final Power Amplifier)

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27
Q

The ________ discharges stored up energy

A

Energy Storage Device

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28
Q

A _____ can be used to smooth out irregular voltage and power levels in the modulator.

A

capacitor bank

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29
Q

what is it called when the SCR is unable to properly reset after firing

A

Hangfire

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30
Q

The _____ transforms ac power to continuous DC power in order to enable the FPA

A

HVPS (High Voltage Power Suppily)

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31
Q

The _____ determines the width of the high-powered pulse that is delivered to the FPA

A

PFN (pulse forming network)

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32
Q

The _____ resets every time the energy storage device discharges

A

charging switch

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33
Q

When the trigger voltage exceeds the critical voltage of the _____, it is forced into conduction.

A

RBDT (reverse-blocking diode thyristor)

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34
Q

_____ circuits generate high impedance to oppose the DC pulse during discharge

A

Saturable reactor

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35
Q

A _____ circuit absorbs unwanted ringing by dissipating high amounts of DC power.

A

resistor

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36
Q

The modulator charging path begins with the _____.

A

DC power supply

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37
Q

It is important to understand the _____ requirements of modulator components in order to troubleshoot radar systems.

A

timing

38
Q

Impedance mismatch can be used to assist the charging cycle in the _____.

A

PFN (pulse forming network)

39
Q

The charging choke and the charging diode double the charge that is stored on the _____.

A

PFN (pulse forming network)

40
Q

_______ allows air traffic controllers to communicate with pilots

A

Amplitude modulation

41
Q

_______ occur when the side lobes drop to zero and contain no energy.

A

Crossover frequencies

42
Q

_______ is the circuit’s ability to pass a signal without distortion.

A

Fidelity

43
Q

An adequate pulse reproduction occurs when the bandpass is equal to the _____ crossover frequency.

A

third

44
Q

The FAA uses _____ pulse compression techniques for transistor radars

A

non-linear FM

45
Q

Harmonics are based on the _____ of the transmitted pulse

A

fundamental frequency

46
Q

The number of harmonics that can pass through a network depends on the _____.

A

bandwidth

47
Q

Most radar systems use a microwave _____ diode that is Foward biased to achieve the desired pulse width

A

PIN (positive-intrinsic barrier-negative)

48
Q

What does pulse width affect

A. Aircraft range resolution
B. Average transmitted RF energy
C. Fundamental frequency
D. Intelligence riding on the carrier frequency
E. Number of harmonics passed through a network

A

Aircraft range resolution
Average transmitted RF energy

49
Q

Spectral analysis allows us to examine a transmitted pulse by plotting _____ versus _____.

A

Frequency Amplitude

50
Q

Achieving bandwidth fidelity varies by the number of _____ components that an amplifier must pass within a given pulse.

A

harmonic

51
Q

The FAA uses pulse compression techniques with _____ FPAs to achieve adequate average power. (ASR-11)

A

solid-state

52
Q

The _____ uses a dual sub-pulse transmission technique to send out a 150 μs transmit pulse. (Radar system)

A

ARSR-4

53
Q

The _______ and ______ are vacuum tube amplifiers.

A

klystron, TWT (traveling wave tube)

54
Q

Pulse klystron amplifiers have a low _______ due to their cavities.

A

bandwidth

55
Q

FAA radars use a ______ to focus the electron beam

A

solenoid

56
Q

The RF input and output are connected by a helical delay line, which reduces the _______ to match the _________

A

RF signal velocity , electron beam

57
Q

_______ occurs as the bunched electrons interact with the electric field of the RF signal

A

Amplification

58
Q

The divider/combiner is the dominant method used in _______ radars(s). (3 answers)

A

ARSR-4
ASR-11
CARSR

59
Q

Microwave transistors require a _______ and _______ pulse for proper functioning

A

low peak power, longer time duration

60
Q

Transistor amplifiers are advantageous over vacuum tube amplifiers because they ______. (3 answers)

A

have a longer life expectancy
have a more reliable power supply
have a simpler construction

61
Q

The FAA uses _____ (modulation) on the transmit pulse frequency

A

NLFM(non-linear frequency modulation)

62
Q

Vacuum tube amplifiers must produce _____ peak, _____ RF pulses.

A

high, short

63
Q

The RF output device must produce a pulse width at the _____ possible within average power limitations.

A

highest PRF

64
Q

Which part of the klystron is nicknamed the “buncher?”

A

first cavity

65
Q

Electrons in the electric field will slow down when the RF signal varies from_____ to ____.

A

181° to 359°

66
Q

The TWT uses a _____ to focus the electron beam

A

permeant magnet

67
Q

The first sub-pulse in an ARSR-4 is transmitted at _____ μs and the second is transmitted at _____ μs

A

90, 60

68
Q

The _____ in a TWT slows down the RF pulse to correspond to the velocity of the electron beam

A

Helix Coil

69
Q

What prevents oscillations by isolating the RF input and output in a TWT?

A

Attenuator

70
Q

The high voltage demands of the _____ often lead to component degradation

A

transmitter

71
Q

Pulse power requirements are listed in the _____ section of the maintenance handbook

A

Standards and Tolerances

72
Q

The voltage standing wave ratio can be calculated from the _______.

A

forward and reverse power readings

73
Q

Transmitted pulse characteristics determine the aircraft’s _____.

A

range resolution

74
Q

RF pulse width is measured from the _____ of the directional coupler

A

forward port

75
Q

Unless otherwise specified, pulse width is measured at the _____ point of the RF pulse.

A

70%

76
Q

Bandwidth is typically measured at the _____ down position on the transmitted pulse. (2 answers).

A

40 dB
50 dB

77
Q

Which devices can be used to measure carrier frequency and transmitter stability? (2 answers)

A

frequency counter
Spectrum analyzer

78
Q

Which pulse-shape characteristics could cause the FPA to not work properly if they are out of tolerance? (3 answers)

A

Fall time
Pulse width
Rise time

79
Q

FAA equipment standards and tolerances can be found in Chapter _____ of the maintenance handbooks

A

3

80
Q

Radar parameters preceded by which symbol must fall within the stated tolerances to meet key performance parameters?

A

Arrow

81
Q

Which parameters are used to measure peak power? 3 answers

A

Peak power
Pulse width
Pulse repetition time

82
Q

Digital average power readings are measured from the_____ on the directional coupler

A

forward port

83
Q

Range resolution is calculated with the speed of light and _____.

A

RF pulse Width

84
Q

Variations in the ____ effect the range resolution

A

pulse width

85
Q

Rise time is measured from the ___ - ___ points on the pulse’s leading edge

A

10%-90%

86
Q

Radar technicians must verify the spectrum by calculating the _____.

A

bandwidth

87
Q

The _____ function sets the power level to 0 dB.

A

Mkr –> CF

88
Q

What are some actions that can be taken to troubleshoot the FPA?

A

Fine tune its cavities
Make sure the output device is within tolerance
Replace it

89
Q

The measured carrier frequency should fall within tolerance of the _____.

A

transmitting frequency

90
Q

Deviations in the ____ from pulse-to-pulse transmission can cause interference to adjacent radar sites.

A

carrier frequency

FAA Radar Concepts (8 decks)

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