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FAA Radar Concepts > Module 5 > Flashcards

Module 5 Flashcards

1
Q

What are the primary functions of a signal processor? Select all that apply.
A. Accept raw target return video from the receiver
B. Condition data based on the appropriate operating mode
C. Control receiver gain
D. Present video to PPI display
E. Provide radar timing signals
F. System testing

A

Accept raw target return video from the receiver
Condition data based on the appropriate operating mode
Present video to PPI display

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2
Q

As a radar target moves away from the radar, the target echoes will _______, and their frequencies will _______.

A

expand, decrease

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3
Q

The radial velocity is _______ the ground speed velocity if the target is moving directly toward the radar.

A

equal to

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4
Q

________ signal processors place returns in a memory storage device before comparing them.

A

Digital

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5
Q

_______ creates a trend analysis of Doppler shift returns.

A

Doppler filtering

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6
Q

The Doppler shift is ________.
A. determined by the angle between the true range and the line-of-sight to the radar
B. the change in frequency as a target moves towards and away from a radar
C. the ground velocity of a target as it moves towards or away from a radar
D. the process of delaying one sample for comparison to the next sample

A

the ground velocity of a target as it moves towards or away from a radar

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7
Q

________ is the component of an aircraft’s groundspeed that is moving toward or away from the radar.

A

Radial velocity

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8
Q

When calculated the ______ using ground velocity, take the cosine of the angle between the aircraft’s true heading and its line of sight to the radar.

A

radial velocity

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9
Q

______ is the process of comparing two sequential intelligence samples to determine whether or not a Doppler shift has occurred.

A

Cancellation

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10
Q

A secondary function of radar signal processors is to _______.

A

provide radar timing signals

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11
Q

Which radar system component generates range and azimuth gates to control related functions?

A

Signal processor

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12
Q

Which of the following are secondary functions of a radar system’s signal processor? Select all that apply.
A. Accept raw target return video from the receiver
B. Control receiver gain
C. Present video to PPI display
D. Provide radar timing signals

A

Control receiver gain
Provide radar timing signals

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13
Q

If an input signal is greater than the reference signal, it moves to the _______.

A

subtractor

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14
Q

Digital to analog conversion is used for ______.

A

sending signals to display devices

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15
Q

______ is the process used to differentiate targets from noise.

A

Constant false alarm rate

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16
Q

If a target signal does not cross the detection threshold, it is called a _____.

A

miss

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17
Q

________ is the process of adding the number of pulses over several PRTs to improve target detection.

A

Integration

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18
Q

If an input signal is below the threshold for the reference signal, it moves on to the _______.

A. adder
B. canceller
C. next comparator
D. subtractor

A

next comparator

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19
Q

Modern radar converters must have which characteristics? Select all that apply.
A. They must be asynchronous.
B. They must be monotonic.
C. They must have high resolution.
D. They must have low dynamic range.

A

They must be asynchronous.
They must be monotonic.
They must have high resolution.

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20
Q

In a(n) _______, the half of the input signal that flows towards the op amplifier affects the output voltage.

A

R-2R ladder network

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21
Q

What indicates the likelihood that a signal is detected while in presence of noise?

A. Constant false alarm rate
B. Probability of detection
C. Probability of false alarm
D. Pulse repetition time

A

Probability of detection

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22
Q

If the detection threshold increases, the probability of false alarm ____ and the probability of detection ____.
A. decreases, decreases
B. decreases, increases
C. decreases, remains constant
D. increases, increases
E. increases, remains constant

A

decreases, decreases

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23
Q

Adding pulses with similar characteristics is called _____.

A

coherent integration

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24
Q

The purpose of MTI (Moving Target Indicator) processing is to _______.

A

suppress fixed target returns and enhance moving target returns

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25
Q

MTI (Moving Target Indicator) processors compare the _______ of each pulse to distinguish fixed targets from moving ones.

A

amplitudes and polarity

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26
Q

A difference in amplitudes between two compared returns indicates a _______ target

A

moving

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27
Q

An echo entering the delay line travels to the summer in how many PRTs (pulse repetition time)?

A

1 PRT (pulse repetition time)

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28
Q

_______ reduces the blind speed effects on a target.

A

Staggering the PRF Pulse Repetition Frequency)

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29
Q

The ______ is not affected by blind phases because it operates independent of the phase.

A

magnitude detector

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30
Q

An MTI (Moving Target Indicator) system uses ______ filtering to remove returns from fixed targets

A

band-reject

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31
Q

Quadrature phase detection measures a received signal’s phase and _______.

A

amplitude

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32
Q

What are the components of a delay line canceller? Select all that apply.
A. Comparator
B. Delay line
C. Magnitude combiner
D. Summer

A

Delay line
Summer

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33
Q

A moving target that produces a Doppler frequency that is an odd multiple of ½ the PRF (Pulse Repetition Frequency)has reached _______.

A

optimum velocity

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34
Q

At optimum speed, a moving target travels _______ wavelength between transmit bursts

A

1/4

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35
Q

Vector processing MTI (Moving Target Indicator) _______ delay line to process phase detector output.

A

uses several

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36
Q

What might increase in weather returns looks like in a pulsed radar system?

A

Extra noise in the system’s average noise

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37
Q

What prevents video saturation from the large amplitude of weather returns?

A

Logarithmic amplifier

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38
Q

What provides sampled range-cell signals that are applied to video input?

A

Digital cell averaging system

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39
Q

If a signal level of interest is greater than the average noise threshold, _______.

A

an output is generated

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40
Q

The _______ was designed to eliminate clutter.

A

MTI (Moving Target Indicator) system

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41
Q

SCV (Sub-Clutter Visibility) is the ratio of _______ that will just cause the canceller voltage from the signal to equal twice the clutter residue.

A. clutter phase to moving target echo initial phase
B. clutter signal strength to moving target signal strength
C. moving target echo initial phase to clutter phase
D. moving target signal strength to clutter signal strength

A

moving target signal strength to clutter signal strength

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42
Q

What is required for maximum canceller performance?

A. The STALO (stable local oscillator) and COHO (coherent oscillator) must vary.
B. The STALO (stable local oscillator) must not vary while the COHO (coherent oscillator) varies.
C. The transmitted signal cannot be stable.
D. The transmitted signal must be stable.

A

The transmitted signal must be stable.

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43
Q

What factors limit MTI (Moving Target Indicator) performance? Select all that apply.
A. Decreased clutter residue
B. Phase change caused by the Doppler Effect
C. Radar system instabilities
D. Small movements in the clutter itself

A

Radar system instabilities
Small movements in the clutter itself

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44
Q

What indicates how well a canceller is removing fixed target returns? Select all that apply.
A. Cancellation ratio
B. Clutter rejection
C. MTI (Moving Target Indicator) improvement factor
D. The transmitted signal

A

Cancellation ratio
Clutter rejection

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45
Q

________ instabilities could prevent fixed targets from being canceled, resulting in a cancellation ratio of one.

A

COHO (coherent oscillator)

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46
Q

Which of the following is a simple CFAR circuit preventing weather from interfering with target detection?
A. Log FTC Fast time Constant)
B. Phase detector
C. Pulsed
D. Microprocessor-based

A

Log FTC (Fast time Constant)

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47
Q

In a pulsed radar system, returns for weather will look like ______ in phase detector output over a ________ range than actual aircraft returns.
A. a decrease, larger
B. a decrease, smaller
C. an increase, larger
D. an increase, smaller

A

an increase, larger

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48
Q

In a ________, a cell-averaging or low pass filter determines a signal’s local average

A

logarithmic amplifier

49
Q

In a logarithmic amplifier, what determines the time and range used to evaluate the signal’s average?

A

Filter cutoff frequency

50
Q

Where is the test cell output applied?

A

Threshold detector

51
Q

A return target will only appear in _______. Therefore, its output _______ increase the average enough to prevent detection.
A. one cell, will not
B. two cells, will
C. three cells, will
D. four cells, will not

A

one cell, will not

52
Q

All ________ are assumed to be equally likely when referring to sub-clutter visibility.
A. false alarms
B. signal strengths
C. target radial velocities
D. target sizes

A

target radial velocities

53
Q

As the clutter ________, it gets harder to see the moving target inside of it.
A. size gets larger
B. size gets smaller
C. strength gets stronger
D. strength gets weaker

A

strength gets stronger

54
Q

SCV (Sub-Clutter Visibility) _______ to compare the performance of two radars operating in the same environment.

A

cannot be used

55
Q

Which characteristic measures MTI (moving target indicator) system performance?

A. Cancellation ratio
B. Clutter rejection
C. MTI improvement factor
D. The transmitted signal

A

MTI (moving target indicator) improvement factor

56
Q

Instabilities in the _______ will increase the amount of clutter residue in a different cancellation ratio.
A. radar frequencyv
B. signal-to-noise ratio
C. system’s signal
D. transmitted signal

A

radar frequency

57
Q

What are some of the factors influencing an MTI receiver’s response to a moving target over clutter? Select all that apply.
A. A moving target’s radial velocity
B. Signal strength of a moving target echo
C. The clutter phase
D. The target’s size

A

A moving target’s radial velocity
B. Signal strength of a moving target echo
The clutter phase

58
Q

What are the characteristics of a digital filter?

A

Frequency and Phase sensitive

59
Q

Setting _______ tunes the multiply and accumulate algorithm. (Digital Filters)

A

coefficients

60
Q

Pulse compression techniques let a system transmit a pulse of _______ and low peak power.

A

long duration

61
Q

________ in the PCF represent modulation values applied in the transmitter.

A

Phasors

62
Q

The final sampling output is obtained at a rate _____ with the desired range resolution ______ the pulse compression filter is used as a phase detector.

A

frequency, phase relationship

63
Q

A digital filter is a(n) ________.

A

algorithm

64
Q

The final sampling output is obtained at a rate _____ with the desired range resolution ______ the pulse compression filter is used as a phase detector.

A. consistent, if
B. consistent, regardless of whether
C. inconsistent, if
D. inconsistent, regardless of whether

A

consistent, regardless of whether

65
Q

What tasks does the MTD processor use digital filter for? Select all that apply.
A. Batch processing
B. Filtering the Doppler shift of targets
C. Pulse compression
D. Understanding what happens once a report is generated

A

Batch processing
Filtering the Doppler shift of targets
Pulse compressioN

66
Q

The purpose of PCF(pulse compression filter) is to remove __________ introduced in the transmitter

A

fm chirp

67
Q

How often is I&Q data generated for the radar’s range cells?

A

Each PRT (pulse repetition time)

68
Q

The first piece of data to enter into memory storage is the ________.

A

first azimuth cell of the first PRT (pulse repetition time)

69
Q

The Doppler filter input is in _____ format for batch processing.

A

BRC (Batch Range Cells)

70
Q

Doppler filters process in _____ order.
A. ascending
B. descending
C. azimuth
D. range

A

azimuth

71
Q

Which of the following is true about the mean level threshold?
A. Each threshold must have a different amplitude
B. It eliminates magnitude data for false targets
C. It generates a new filter threshold after each comparison
D. The filter value is combined with the threshold data for comparison

A

The filter value is combined with the threshold data for comparison

72
Q
  1. What is the possibility a signal will be detected when in noise?
    A. Constant false alarm rate
    B. Probability of detection
    C. Probability of false alarm
    D. Thresholding
A

Probability of detection

73
Q

What is a disadvantage of raising the CFAR (constant false alarm rate) threshold?

A

It could eliminate valid targets

74
Q

A clutter map allows _____ targets to be detected by storing the nominal zero-velocity returns as thresholds.

A

zero velocity

75
Q

What is another name for clutter mapping?

A

Time average CFAR(constant false alarm rate)

76
Q

It is possible for a single target to produce several primitive target reports extending over several BRCs that encompass multiple Doppler filters.
A. True
B. False

A

True

77
Q

What does the primitive target report contain? Select all that apply.
A. Amplitude of origin
B. Doppler filter of origin
C. Range of origin
D. Velocity of origin

A

Amplitude of origin
Doppler filter of origin
Range of origin

78
Q

The representation created by a Geo-Map cannot include _____.

A

airport grounds

79
Q

What does an MTD Geo-Map do? Select all that apply.
A. Allows zero velocity targets be detected
B. Detects moving targets
C. Identifies problem areas in known geographic locations
D. Prevents road traffic from being displayed as moving targets

A

Prevents road traffic from being displayed as moving targets
Identifies problem areas in known geographic locations

80
Q

What converts range data to batch ordered data?

A

Memory storage

81
Q

Radar transmits and receives echoes in a range-ordered format _____, for the entire range system.

A

one cell at a time

82
Q

What is the format used to output from memory storage?

A

Batch-ordered data

83
Q

Coefficients in _____ compromise data that allows targets to be sorted by their radial velocity.

A

Doppler filters

84
Q

Doppler filters operate in groups called _____, in which each filter is tuned to a progressively higher frequency.

A

banks

85
Q

The specific _____ of each Doppler filter is determined by the selection of coefficients.

A

optimum frequency

86
Q

When a filter produces its _____ the involvement of adjacent filters is minimized.

A

optimum response

87
Q

What changes continuously to eliminate magnitude data that is not a valid target?

A

The dynamic mean threshold

88
Q

The process of suppressing false alarms caused by noise, interference, or weather is _____.

A

CFAR (Constant False Alarm Rate)

89
Q

What is the ability to maintain the false alarm rate at a predetermined level even as external conditions change?

A

Adaptive CFAR (constant false alarm rate)

90
Q

What is the likelihood of noise being mistaken for a target?

A

Probability of false alarm

91
Q

The probability of false alarm must be _____ to ensure the number of false alarms is as small as possible?

A

low

92
Q

The primitives can be from _____ different PRFs and are combined in an m or n decision

A

2

93
Q

What is meant by a tangent target?

A

It is a moving target that does not produce a radial velocity

94
Q

What causes a zero-velocity filter to become an alarm?
A. The time-average CFAR must average the radar inputs from the zero Doppler filter
B. The magnitude of the zero-velocity target must be less than the stored threshold
C. The magnitude of the zero-velocity target must be greater than the stored threshold
D. The clutter map must average the zero velocity echoes and compare it to the stored threshold

A

The magnitude of the zero-velocity target must be greater than the stored threshold

95
Q

A _____ target may take up several consecutive range cells.

A

Large

96
Q

Which of the following presents an issue for MTD target processing?
A. Inclement weather
B. Moving vehicles
C. Slow moving aircraft
D. Trees

A

Moving vehicles

97
Q

What determines the range center’s location?

A

Range-straddle test

98
Q

Azimuth centroiding uses ________ to determine a target’s center.

A

algorithms

99
Q

What are the four universal steps in track-while-scan processing?
A. Association
B. Correlation
C. Track initiation
D. Track updating
E. Track uploading

A

A. Association
B. Correlation
C. Track initiation
D. Track updating

100
Q

Which step of the track-while-scan process uses the track-to-report association probability?

A

Conflict resolution

101
Q

Which process associates completed target reports with target reports generated in a secondary radar system?

A

Merge function

102
Q

Which process involves receiving target plot and track data as well as other data?

A

Formatting

103
Q

Which equipment provides interface and protocol conversion for communication between radars, end users, and networking requirements for modern radar’s computer or microprocessor controlled functions?

A

Communications interface

104
Q

What is the final functional process in sending radar data to the end-user?

A

Remoting

105
Q

What is the process of establishing range and azimuth centers?

A

plot extraction

106
Q

What is the purpose of the range resolution test?

A

To determine if other targets exist in adjacent range cells

107
Q

What is the best resolution for azimuth centroiding?

A

CPI (coherent processing interval)

108
Q

What is the process of eliminating plot characteristics for valid primitive clusters associated in azimuth and range?

A

Plot extraction

109
Q

During which step in the track-while-scan process is an imaginary azimuth window placed around each existing track?

A

Association

110
Q

If more than one report is in the associated window _______ associates each report with existing track in the window.

A

conflict resolution

111
Q

Which process occurs after a new report is received and a check is performed to determine if a target is located in the window of an existing track?

A

Track initiation

112
Q

What happens when a track initiation report finds an unassociated track that is located in the window of an existing track?
A. The unassociated track is not filed
B. The unassociated track is added to a new file
C. The unassociated track is added into a file selected at random
D. All of the tracks are combined into one file

A

The unassociated track is added to a new file

113
Q

What is declared if a track has new reports associated with it for several antenna scans?

A

Correlation

114
Q

During ________, a target-tracking file is made current and a check is performed to verify a target is moving.

A

track updating

115
Q

Which of the following is true of the Legacy format?
A. The Legacy format is determined by the formatter protocol
B. The Legacy format is IP-based
C. The Legacy format keeps a complete history of targets in the target-tracking file
D. The Legacy format transfers data through a modem

A

The Legacy format transfers data through a modem

116
Q

In which step is it decided whether a return from the primary radar and reply from the secondary radar are from the same target?

A

Merge function

117
Q

Other remote-related functions like CARSR _________ will communicate status and control with the end-user.
A. APU (Azimuth Processing Unit)
B. RMC (Remote and Monitor Control)
C. RSC (Radar Set Control)
D. TMCT (test maintenance and control terminal)

A

RMC (Remote and Monitor Control)

118
Q

Which CARSR component converts Ethernet data for the receiver channels?
A. CD-2 data switch
B. MPS (multi-protocol server)
C. RSC (Radar Set Control)
D. TMCT(test maintenance and control termina)

A

MPS

FAA Radar Concepts (8 decks)

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