Radar Flashcards
RADAR is an acronym for?
RAdio Detection And Ranging
How is RADAR modulated?
You could have answered with any of the following: 1. Pulse 2. Pulse modulated
What are two chief attributes of RADAR?
Detection at large distances and accurately locating one’s position.
XBand Radar what is the wavelength?
You could have answered with any of the following: 1. 3 cm
XBand Radar what is the frequency band in MHz?
You could have answered with any of the following: 1. 93009500
SBand Radar what is the wavelength?
You could have answered with any of the following: 1. 10 cm
SBand Radar what is the frequency band in MHz?
You could have answered with any of the following: 1. 29003100
Pulse modulated Radar pulses are frequently ____ microsecond or less.
You could have answered with any of the following: 1. one 2. 1
What type of polarization do marine Radars commonly have? 1. Vertical 2. Horizontal
The correct answer is: Number 2 Horizontal
Define frequency.
Number of cycles completed in one second.
The power at points in the beam is _______ proportional to the ______ of the distance 1. directly square 2. inversely square 3. directly cube 4. inversely cube
The correct answer is: Number 2 inversely square
Beam width is measured as the angle between the ______ power points. 1. even 2. squared 3. half 4. quarter
The correct answer is: Number 3 half
Typical horizontal beam width is between ____ and ____ degrees. 1. 1.5 2.0 2. 0.65 2.5 3. 0.65 2.0 4. 1.0 2.5
The correct answer is: Number 3 0.65 2.0
Typical vertical beam width is between ____ and ____ degrees. 1. 10 30 2. 15 30 3. 15 35 4. 20 35
The correct answer is: Number 2 15 30
Narrower beam widths are achieved using ______ wavelengths. 1. Shorter 2. Longer
The correct answer is: Number 1 Shorter
For a given wavelength narrower beam widths are achieved using ______ antennas. 1. Smaller 2. Longer
The correct answer is: Number 2 Longer
At lower frequencies the interference pattern is _____ coarse than at higher frequencies. 1. Less 2. More
The correct answer is: Number 2 More
The pitch and roll of a ship _____ affect the structure of the interference pattern. 1. does 2. does not
The correct answer is: Number 2 does not
The bending of a wave as it passes and obstruction is _______. 1. refraction 2. diffraction
The correct answer is: Number 2 diffraction
The bending of a wave due to atmospheric conditions is _______. 1. refraction 2. diffraction
The correct answer is: Number 1 refraction
Refraction takes place when the ______ of a wave is changed
velocity
Calculation of the radar horizon ignores ______. 1. refraction 2. diffraction
The correct answer is: Number 1 refraction
SUBrefraction occurs in ______ regions and _______ radar range? 1. temperate increases 2. temperate decreases 3. arctic increases 4. arctic decreases
The correct answer is: Number 4 arctic decreases
SUPERrefraction occurs generally in _______ environments and _______ radar range. 1. tropic increases 2. tropic decreases 3. arctic increases 4. arctic decreases
Caused when warm air blows over cool water weather must be calm with little disturbance. The correct answer is: Number 1 tropic increases
Extra Superrefraction occurs when?
When there is atmospheric ducting. Can increase range to 1400 miles but contacts outside of the duct are not likely to have a return.
Ducting occurs in areas with?
Monsoonal climate reoccurring low barometric pressure.
Reduction of the intensity of a wave along its path is known as?
Attenuation
Which radar suffers less from attenuation? 1. 3 cm (XBand) 2. 10 cm (SBand)
The higher the frequency the greater the attenuation. The correct answer is: Number 2 10 cm (SBand)
List in decreasing order of creating attenuation 1. Snow Hail Dust Rain Dense Fog 2. Rain Dense Fog Snow Hail Dust 3. Rain Snow Dense Fog Dust Hail
The correct answer is: Number 2 Rain Dense Fog Snow Hail Dust
Which frequency is better for long range detection 1. Lower 2. Higher
Lower frequency has a longer wavelength therefore longer detection range. The correct answer is: Number 1 Lower
Doubling the peak power of a radar increases its range by 1. 10% 2. 25% 3. 50% 4. 100%
The correct answer is: Number 2 25%
The longer the pulse length the greater the detection range because the greater the amount of ________ transmitted
energy
The more concentrated the beam width the _______ the detection range. 1. less 2. greater
The correct answer is: Number 2 greater
The faster the antenna rotation _______ the detection range. 1. less 2. greater
Particularly for small targets. The correct answer is: Number 1 less
Minimum range is determined primarily by __________.
pulse length
Depending on the height of the transceiver small targets may escape under the lower edge of the vertical beam.
The correct answer is: True
Which is more accurate the use of a fixed range ring or a variable range marker (VRM)? Assuming the target falls on the ring? 1. Range Ring 2. Variable Range Marker
Range rings are accurate to 1.5% of the scale in use. VRMs are accurate to 2.5% of the scale in use The correct answer is: Number 1 Range Ring
Too high of a gain setting will cause can cause a target to bloom and appear closer than it really is.
The correct answer is: True
Accuracy of a marine radar should not be considered better than +/ _____ yards in the best conditions.
You could have answered with any of the following: 1. 50 2. fifty
If the pulse length is too long two separate targets can merge into one target.
The must be separated by a distance greater than one half the pulse length. The correct answer is: True
Radiofrequency energy travels at approximately ____ yards per microsecond 1. 254 2. 316 3. 328 4. 425
The correct answer is: Number 3 328
Smaller horizontal beam widths make for ______ accurate bearing measurements. 1. more 2. less
The correct answer is: Number 1 more
Bearing accuracy can be improved by _______ the gain setting. 1. decreasing 2. increasing
Causes targets to bloom less. The correct answer is: Number 1 decreasing
Bearing measurements are more accurate on _______ targets. 1. larger 2. smaller
The center on a small target can be more accurately identified. The correct answer is: Number 2 smaller
_______displays provide higher bearing accuracy. 1. stabilized 2. unstabilized
Not affected by yawing. The correct answer is: Number 1 stabilized
Generally ________wavelengths radars are more affected by weather. 1. shorter 2. longer
XBand (3cm) is more affected. The correct answer is: Number 1 shorter
The higher the antenna is mounted the longer its detection range.
The correct answer is: True
A target with a 90 degree aspect will reflect the strongest return.
The correct answer is: True
A smooth conical shape will return a strong signal.
A rough conical shape may have a return The correct answer is: False
A rough texture generally reflects better than a smooth texture.
The correct answer is: False
The motion of a target’s movement is shown relative to the observing ship.
Relative motion
The true motion of a target’s movement and the observing ship’s movement.
True motion.
A relative motion display will show a fixed target’s movement as equal and opposite to the observing ship.
The correct answer is: True
When using a stabilized radar for collision avoidance which is preferred? 1. ground stabilized 2. sea stabilized
Assuming that ownship and the target are affected by the same current. The correct answer is: Number 2 sea stabilized
FTC stands for?
Fast Time Constant
FTC has an effect _______. 1. over the entire screen 2. increasing radially from the center
The correct answer is: Number 1 over the entire screen
FTC operates by ________.
Reducing receiver sensitivity. Thereby lessening the strength of targets on the display.
Rain clutter control provides a variable _______.
FTC (Fast time constant)
STC stands for?
Sensitivity Time Control (Also known as Sea Clutter Control AntiClutter Control Swept Gain Suppressor)
STC has an effect _______. 1. over the entire screen 2. increasing radially from the center
The correct answer is: Number 2 increasing radially from the center
When using the performance monitor any reduction of _____% or more of the plume is an indication the radar needs servicing. 1. 10 2. 15 3. 20 4. 25
The correct answer is: Number 3 20
As pulse length increases the pulse repetition rate ________. 1. decreases 2. increases
The correct answer is: Number 1 decreases
A lower pulse repetition rate is needed on longer ranges to insure _____.
That the pulses sent out have time to return prior to the next pulses being sent.
A higher pulse repetition rate on lower range scales will….
create stronger pips because they are painted more frequently.
In order to use direction of relative motion (DRM) collision avoidance the radar used must be ________.
Stabilized It also helps to have a persistent image
When maneuvering for a vessel with a high speed of relative motion (SRM) the observed change is _______ than for a vessel with lower SRM. 1. more 2. less
The correct answer is: Number 2 less
The effectiveness of a turn to avoid collision is ________ by turning away from the contact. 1. enhanced 2. minimized
The correct answer is: Number 1 enhanced
A contact is always ______ in up the scope cases 1. Slower 2. Faster
The correct answer is: Number 2 Faster
A contact is always ______ in across the scope cases 1. Slower 2. Faster
The correct answer is: Number 2 Faster
A contact is always ______ in down the scope cases 1. Slower 2. Faster
The correct answer is: Number 1 Slower
DRM RULE #1 A target who is up the scope
when own ship turns right
DRM RULE #2 A target who is down the scope
when own ship turns right
DRM RULE #3 A target who is across the scope
when own ship turns right or left
DRM RULE #4 When ownship speed reduces the DRM of all other targets will swing ________. 1. Up Scope 2. Down Scope 3. Stay Steady
RADAR p. 145 The correct answer is: Number 1 Up Scope
DRM RULE #5 When ownship speed increases the DRM of all other targets will swing ________. 1. Up Scope 2. Down Scope 3. Stay Steady
RADAR p. 145 The correct answer is: Number 2 Down Scope
DRM RULE #6 When a target’s relative speed is high the effect of ownship’s action is ______. 1. low 2. high
RADAR p. 145 The correct answer is: Number 1 low
DRM RULE #7 When a target’s relative speed is low the effect of ownship’s action is ______. 1. low 2. high
RADAR p. 145 The correct answer is: Number 2 high
Multiple reflection echos can often be removed by? 1. decreasing the gain 2. adjusting the STC 3. adjusting the FTC
The correct answer is: Number 1 decreasing the gain and Number 2 adjusting the STC
Side lobes usually only show on ______ ranges and _____ targets. 1. Short Weak 2. Short Strong 3. Long Weak 4. Long Strong
The correct answer is: Number 2 Short Strong
The approximate range of a SART is _____ nautical miles.
You could have answered with any of the following: 1. eight 2. 8
SARTs are triggered by ___ cm radars. 1. 3 2. 10
Some are triggered by 10cm also. The correct answer is: Number 1 3
An ____ band radar has better detection in precipitation. 1. S 2. X
The correct answer is: Number 1 S
For the greatest bearing accuracy a target should be placed _______ by selecting the proper range. 1. in close 2. extreme edge of the screen
The correct answer is: Number 2 extreme edge of the screen
ARPA data is only as accurate as the speed and heading input.
The correct answer is: True
The IMO standards dictate a screen diameter of depending on the size of the vessel. 1. 180mm 2. 250mm 3. 340mm
The correct answer is: All Of The Above
IMO dictates that the bearing resolution shall be ______ degrees or better. 1. 1.0 2. 1.5 3. 2.0 4. 2.5
The correct answer is: Number 4 2.5
Per IMO standards a Radar should have bearing accuracy of +/ ____ degree or better.
You could have answered with any of the following: 1. 1 2. one
Per IMO standards a Radar should sweep at least ______ times per minute.
You could have answered with any of the following: 1. 12 2. twelve
Per IMO standards a Radar should continue to perform with rolling and pitching up to _____ degrees.
You could have answered with any of the following: 1. 10 2. ten
Per IMO standards a Radar range rings or VRM should not be in error exceeding _____ % of the scale in use or ______ meters whichever is greater. 1. 1.5 70 2. 2.0 70 3. 1.5 50 4. 2.0 50
The correct answer is: Number 1 1.5 70
Per IMO standards in true motion the trace origin should not exceed ______ % of the radius of the display (except in manual override).
You could have answered with any of the following: 1. 75
Per IMO standards two radars should be installed so that they can be operated independently with out being dependant on the other.
The correct answer is: True
The term circle spacing is always ______ yards unless otherwise designated.
You could have answered with any of the following: 1. 1000
A crossband RACON will show on the screen with the normal radar image.
A crossband RACON does not operate on the same frequency a marine radar and must have a receiver specially able to tune to its frequency. If so the normal image does not display
A inband RACON will show on the screen with the normal radar image.
A inband RACON does operate on the same frequency as marine radar. So the normal image does display with the RACON. The correct answer is: True
With the ______ circuit in operation only the nearer edge of an echo having a long time duration is displayed. 1. STC 2. Sea Clutter 3. FTC 4. Gain
The correct answer is: Number 3 FTC
Microwaves are generally considered to be the region in which radar operates.
The correct answer is: True
_______ polarization is used for reducing rain clutter. 1. Vertical 2. Horizontal 3. Circular
The correct answer is: Number 3 Circular
A corner reflector is made of _____ plates mutually perpendicular. 1. two 2. three 3. four 4. five
The correct answer is: Number 2 three
Which is a radar beacon which continuously transmits a signal appearing as a radial line? 1. RAMARK 2. RACON
The correct answer is: Number 1 RAMARK
The image painted by the sweep is always an accurate representation of the shoreline.
The correct answer is: False
On relative motion displays landmasses move in directions and rates equal and opposite to the actual motion of the observer.
The correct answer is: True
A chain of islets or small targets in a line may appear as a solid line when viewed ______ to the radar beam. 1. perpendicular 2. lengthwise
The correct answer is: Number 1 perpendicular
Why may landmasses show ‘apparent speed’ when being approached from long distance?
The beam will begin by hitting high land farther off then move down slope to land closer to.
Returns from hilly ground tends to be ______.
Blotchy
Low bare islands produce _______ echos. 1. weaker 2. stronger
The correct answer is: Number 1 weaker
Low treed islands produce _______ echos. 1. weaker 2. stronger
The correct answer is: Number 2 stronger
Target images are distorted _________ by an amount equal to the effective ________ beam width. 1. radially vertical 2. radially horizontal 3. angularly vertical 4. angularly horizontal
The correct answer is: Number 4 angularly horizontal
Target images are distorted ________ by an amount equal to onehalf the ________. 1. radially pulse repetition rate 2. radially pulse length 3. horizontally pulse repetition rate 4. horizontally pulse length
The correct answer is: Number 2 radially pulse length
Due to beam width distortion a strait or nearly strait shoreline will appear ________. 1. angled 2. straight 3. crescent shaped
The distortion increases as the angle between the beam axis and the shoreline decreases. The correct answer is: Number 3 crescent shaped
Distortion due to ___________ is responsible for more confusion than any other cause.
radar shadows
Electronic interference effects are greater at short range.
The correct answer is: False
The appearance of spoking is indicative of the need for equipment maintenance.
The correct answer is: True
The echo from a overhead power cable appears as a single echo always ________ to the line of the cable. 1. parallel 2. perpendicular
The correct answer is: Number 2 perpendicular
A ______ provides bearing and range information. 1. RACON 2. RAMARK
The correct answer is: Number 1 RACON
RACONs are limited to line of sight.
The correct answer is: True
Radar bearings are more accurate than visual gyro bearings.
The correct answer is: False
Fixes from radar bearings or ranges are more accurate? 1. bearings 2. ranges
The correct answer is: Number 2 ranges
Fixing by tangent bearings is one of the ______ accurate methods 1. least 2. most
The correct answer is: Number 1 least
Right tangent bearings should be _______ by half the horizontal beam width. 1. increased 2. decreased
The correct answer is: Number 2 decreased
Parallel indexing is best suited for use with a(n) ________ radar. 1. stabilized 2. unstabilized
The correct answer is: Number 1 stabilized
The distance of an object when it passes abeam if the vessel was to pass the target.
Cross Index Range
The distance at which an object tracking on a parallel line would be on a new track.
Dead Range
The point at which the actual maneuver is made to insure that the object being indexed is on the new track line taking into account the advance and transfer.
Wheel Over Point
