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Radar > Test 2 > Flashcards

Test 2 Flashcards

1
Q

How does inclement weather effect radar?

A

Max range of contacts is reduced and unwanted echoes are produced by sea return

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2
Q

How do you reduce unwanted sea clutter?

A

Reduce receiver gain or switch to a shorter pulse length

Best option is to turn up STC

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3
Q

At what distance does sea return disappear?

A

6-8 miles

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4
Q

STC

A

Sensitivity time control

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5
Q

The higher the vessels radar antenna above the water,

A

The greater the sea clutter effect

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6
Q

Radar can be used to determine the direction of true wind (even at nite) by

A

Observing the area of sea clutter on the radarscope

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7
Q

Rain, hail, and snow may return echoes that appear as

A

Blurred or cluttered areas

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8
Q

Heavy precipitation tends to

A

Absorb pulse strength and decrease maximum detection range

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9
Q

FTC

A

Fast time constant

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10
Q

FTC control reduces the length of

A

Pulse echoes

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11
Q

Does FTC have any effect on actual length of transmitted pulses?

A

No

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12
Q

FTC is sometimes referred to as

A

Differentiator

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13
Q

In inclement weather what radar is best?

A

10cm

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14
Q

If a suspected target is within an area of precipitation,

A

Use the FTC circuit to reveal stronger echoes

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15
Q

If a suspected target lies beyond precipitation,

A

Temporarily increase receiver gain

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16
Q

Land masses are generally recognizable because of the

A

Steady brilliance of the relatively large areas

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17
Q

Weak echoes received at low tide

A

Disappear at high tide

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18
Q

What man made structures make good radar targets?

A 
Breakwaters
Jetties
Piers
Bridges
Building
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19
Q

Small boats can be distinguished from buoys by

A

Plotting

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20
Q

What enhances otherwise poor target response of buoys and small boats?

A

Radar reflectors

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21
Q

Radar reflectors send echoes

A

180* back the direction it came from

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22
Q

Racon

A

Radar beacon

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23
Q

A racon is a

A

Small transceiver

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24
Q

Racons register on the PPI as

A

Morse code signal

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25
Q

Modern racons that respond to both x and s band radars are called

A

Frequency agile

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26
Q

Because of beam width distortion,a straight or nearly straight shoreline often appears

A

Crescent shaped

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27
Q

Pulse length distortion increases as the angle between the

A

Beam axis and shoreline decreases

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28
Q

Indirect or false echoes are caused by

A

Reflection of the main lobe of the radar beam off ships structures such as stacks and kings posts

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29
Q

Multiple echoes may occur when a strong echo was received from another ship at

A

Close range

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30
Q

FTE

A

Falls targets ellimination

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31
Q

How is spoking distinguished from interference effects ?

A

The lines are straight on all range scale settings, and are lines rather than a series of dots

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32
Q

Spoking indicates a need for

A

Maintenance or adjustment

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33
Q

What can also indicate a need for maintenance on the PPI?

A

Serrated range rings

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34
Q

ARPA

A

Automatic radar plotting aid

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35
Q

ARPA applies to radar units that allow

A

Automatic acquiring, tracking, plotting of radar targets

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36
Q

The purpose of ARPA is

A

Collision avoidance

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37
Q

Observing a vessel’s course and speed of referred in

A

Relative motion

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38
Q

ARPA error is based on

A

+/-10° of roll

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39
Q

ARPA accuracy values required after one minute

A

95% probability

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40
Q

EPA

A

Electronic plotting aids

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41
Q

Smaller vessels not required to have ARPA are frequently fitted with

A

EPA

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42
Q

What did the IMO implement in 1990?

A

The two observer requirements for ARPA

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43
Q

What was the beneficial consequence of the two observer requirement?

A

No more hooded radars

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44
Q

What is required for ARPA to track a target?

A

Sufficient signal strength and persistence

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45
Q

What is defined by the pulse length and beam width?

A

Resolution cell

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46
Q

CFAR

A

Constant false alarm rate

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47
Q

If there are more than 20 targets that meet the CFAR criteria, ARPA will select the

A

20 most dangerous targets according to range

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48
Q

What will happen when ARPA selects targets for tracking?

A

a visual and audible alarm will sound

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49
Q

When ARPA is tracking a target it is performing mathematical calculations based on

A

Past target positional data to determine target motion

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50
Q

What are the two purposes in determination of target motion?

A

Provides the radar observer with target information necessary for collision avoidance, and move the tracking gate to allow tracking to continue

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51
Q

ARPA calculates target motion based on past positions through a process known as

A

Least squares regression or smoothing

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52
Q

Tracker cells usually measure less than

A

Half degree in angular measure, and no more than .025nm in range

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53
Q

As tracking continues and more positions are recorded, the measure of confidence in the predicted track of the target increases and a

A

More accurate presentation of actual target motion is provided

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54
Q

A smaller tracking gate has the advantage of less likelihood of target last through

A

Rain clutter, sea clutter, proximity to other targets

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55
Q

What is a disadvantage of a small tracking gate?

A

Possible loss of the target

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56
Q

When a target is not found during any successive antenna sweep,

A

The size of the tracking gate will increase to find it

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57
Q

The computer algorithms that controls movement and size of the tracking gate is known as

A

Rate aiding, or Kalman filtering

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58
Q

When will ARPA calculate accurate relative data?

A

Within one minute from the start of tracking

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59
Q

When will ARPA provide true data?

A

After about two minutes of tracking

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60
Q

What happens after three minutes of tracking?

A

The oldest data is erased

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61
Q

If automatic tracking, the number of targets to track must be at least

A

20

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62
Q

What is the minimum number of target to track if manually tracking?

A

10

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63
Q

Where do vectors begin?

A

At the contacts present position

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64
Q

The length of a vector depends on the

A

Time that the operator enters

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65
Q

The primary function of marine radar is_________, not__________

A

Collision avoidance; navigation

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66
Q

Relative vectors do not give an indication of

A

Target aspect

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67
Q

In confined waters, relative vectors are less useful. In other words use

A

True vectors

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68
Q

VRM

A

Variable range marker

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69
Q

EBL

A

Electronic bearing line

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70
Q

Do faulty gyrocompass or speed log inputs have any affect on the accuracy of the relative vector presentation?

A

No

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71
Q

ARPA should normally be set on

A

True vectors

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72
Q

Is accuracy of true vectors seriously degraded by any input error from the speed log or Gyro?

A

Yes

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73
Q

A 1° Gyro error is for practical purposes

A

Insignificant

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74
Q

A 1 knot error of speed input can lead to

A

Disaster

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75
Q

Acura target tracking depends on a

A

Steady state condition

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76
Q

What are main causes of vector instability?

A

A target with too little time in track; the contact maneuvers; own ship maneuvers; contact with poor radar target response; fluctuating Doppler speed login put; unstable or hunting gyrocompass

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77
Q

Any large course or speed change requires

A

A minute or so to settle before any further collision avoidance assessments are made

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78
Q

What allows a navigator to see predicted changes in all tracked relative plots resulting from a proposed maneuver by their own ship?

A

Trial maneuver

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79
Q

What are the steps in trial maneuver?

A

Determine any constraints; select a new CPA; select relative vectors; extend vector time to determine collision of desired CPA; turn on trail maneuver and set MX point; Adjust controls for ship or speed to move the new relative motion line; read the new course and/or speed after the vectors of settled; Exit trial maneuver and give command to alter course and or speed

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80
Q

Target past positions can be displayed by a series of at most

A

Four dots equally spaced in time

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81
Q

When will ARPA emit an alarm to denote that a target is lost?

A

When no evidence of the target is found after five successive sweeps of the antenna

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82
Q

What does ground stabilize use as a frame of reference?

A

Land features

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83
Q

What is also used to ground stabilize the ARPA?

A

GPS

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84
Q

Integrated ECDIS and ARPA use

A

GPS ground stabilization

85
Q

True vectors represent targets and own ship courses and speeds through the water

A

See stabilized

86
Q

Relative vectors in both ground and sea stabilized are

A

Identical

87
Q

a polygonal shape placed around a contact that indicates a range of coarse for your ship not to steer if it is desire to maintain a minimum desirable CPA is called

A

(PAD) predicted area of danger

88
Q

When is PAD best used?

A

In open ocean with a few targets

89
Q

What is the only commercial vessel exempted from AIS?

A

Fishing vessel

90
Q

In what band does AIS broadcast

A

VHF

91
Q

What is the range of VHF?

A

20–30 miles

92
Q

AIS can be invaluable for warning of contacts

A

Well beyond normal radar range

93
Q

AIS may continue display a targets location even if it becomes

A

Shadowed by intervening land or obscured by rain clutter

94
Q

The greatest asset that AIS provides is the ability to make

A

Positive identification of target vessels on the radar screen

95
Q

When a target vessel is rolling in pitching and moderate to heavy seas, the point of greatest target response may shift location over the targets surface due to the constantly shifting target aspect.

A

Glint

96
Q

Glint standard deviation =

A

1/6 the length of ship

97
Q

Bearing error due to

A

Rolling of own ship

98
Q

Range error due to

A

Own ship rolling

99
Q

What is the most common source of all ARPA errors not due to miss interpretation by the radar observer?

A

The Doppler speed log

100
Q

The accuracy of the Doppler speed log output should be

A

Frequently monitored by the observer

101
Q

Information transferred from a week target to a stronger target or land feature if they appear in the same tracking gate is known as

A

Targets swap

102
Q

A big shift in the point of target response, as when a target turns in the aspect changes, causes the track vessel to appear as if it sped away is known as

A

Centroid shift

103
Q

A complacent observer is open to making

A

Careless mistakes

104
Q

SAR

A

Search and rescue

105
Q

What are the four search and rescue patterns?

A

Expanding square; sector; parallel; ship/aircraft coordinated

106
Q

The US Coast Guard operates how many racons?

A

About 80

107
Q

Who other than the US Coast Guard within the United States operates racons?

A

Owners of oil platforms

108
Q

RACONS Are used to

A

Mark like houses in navigation buoys; navigate spans under bridges; identify centerlines and turning points; offshore oil platforms and other structures including approximately 35 in the gulf of Mexico

109
Q

To avoid masking important radar targets beyond the beacon, racons
only operate

A

Part of the time

110
Q

Racons Usually operate in what band?

A

3 cm x band

111
Q

A microsecond is

A

One millionth of a second

112
Q

A nanosecond is

A

One billionth of a second

113
Q

How far can light travel in one nanosecond?

A

11.8 inches

114
Q

What is the range of a RACON?

A

Line of sight, normally over 15 nautical miles

115
Q

RACONS transmit and approximately___microsecond Morse encoded response less than_____nanoseconds later back to the radar on that frequency.

A

25; 700

116
Q

What on a radar could mask a RACON return?

A

Anti-clutter rain control

117
Q

A wideband Beacon which transmit continuously on the radar bands without having to be triggered by an incoming radar signal.

A

Ramark

118
Q

Are RAMARKS used in the US?

A

No

119
Q

SART

A

Search and rescue transponder

120
Q

A SART will only respond to a

A

9 GHz X band (3 cm wavelength) radar

121
Q

What range well an x band radar Trigger a SART?

A

Eight nautical miles

122
Q

When a SART detects a signal it will immediately transmit

A

12 pulses on the same frequency

123
Q

You would expect to find two radar’s installed on vessels of what description?

A

Greater than 10,000 GRT

124
Q

SOLAS compliant radar’s must be capable of operating in the

A

Stabilized mode

125
Q

Is it a requirement of SOLAS that, when in or near restricted visibility, a continuous watch of the radar be maintained?

A

No, it is only a recommendation

126
Q

What type of beam width does an antenna wide in the horizontal dimension produce?

A

Narrow

127
Q

Describe what would happen to a target on your radar when it enters an acquisition zone

A

The target would be automatically acquired triggering a visual and audible alarm

128
Q

Radar observer endorsements are required on licenses for US deck officers on vessels of

A

300 gross tons more more equipped with radar

129
Q

What must be violated before an alarm is activated on a danger target?

A

CPA and TCPA

130
Q

What are the effects of electromagnetic radiation?

A

Refraction, reflection, attenuation, defraction

131
Q

When making landfall the 00W may increase the range scale to

A

Assist in determining the distance of landfall

132
Q

When increasing the range the 00W may need to

A

Adjust gain and clutter controls

133
Q

When a target has been found be sure to

A

Crosscheck the information with all available means

134
Q

Landmasses may have descriptive layout of the land according to the chart, but may become masked (or distorted) due to the

A

Width of the beam Width

135
Q

Targets located on the other side of a target may be lost due to the loss of pulse detection, which is called

A

Shadowing

136
Q

Radar conspicuous target is one which produces a

A

Good response that can be positively identified

137
Q

What are the two techniques to aid in determining position?

A

Line of position (bearing); circle of position (range)

138
Q

A line indicating a series of possible positions of a craft, determined by observation or measurement.

A

Line of position

139
Q

True bearing is the bearing relative to

A

True North

140
Q

Relative bearing is a bearing relative to

A

Heading or to the craft

141
Q

What are the two factors that should be taken into account when determining the exact location of another target?

A

Gyro error and beam width error

142
Q

What is more accurate for obtaining fixes, radar bearings or radar ranges?

A

Radar ranges

143
Q

Which is more accurate, a Gyro bearing or a radar bearing?

A

Gyro bearing

144
Q

What is vital to avoid navigation errors?

A

Crosschecking one method against the other

145
Q

What is a method that allows for constant monitoring of the vessels position?

A

Parallel indexing

146
Q

Are reflection plotters common?

A

No

147
Q

ECDIS

A

Electronic chart display information systems

148
Q

An ENC is an

A

Electronic chart issued by a national hydrographic authority

149
Q

Up to date chart requirements are regulated by

A

V/19, and V/27 or the 1974 SOLAS convention

150
Q

ENC’s produced by a government hydrographic office

A

Official

151
Q

Charts produced by private companies

A

Unofficial

152
Q

A commercial electronic chart system not designed to satisfy requirements of the IMO

A

ECS

153
Q

An ECS HAS TO be used in conjunction with

A

Paper charts

154
Q

What else can be considered an ECS?

A

A cell phone

155
Q

The digital database which electronic charts are produced

A

Electronic Chart Data Base

156
Q

The hydrographic data base from which the ENC is produced

A

Electronic Navigation Chart Database

157
Q

What is considered to be equivalent to a paper chart

A

SENC

158
Q

If just one of the official requirements for an ECDIS are not met,

A

The system has the status of an ECS

159
Q

Benefits of an ECDIS

A

Reduced workload for the navigator; navigation in real time; automatic route monitoring; automatic track control; prediction for special maneuvers; availability of chart at night without night vision loss; access to additional information resources

160
Q

Disadvantagesof ECDIS

A

Too much info on screen; submenus complex; chart size reduced; symbols may be misinterpreted; complacency

161
Q

What is becoming the essential tool for the watch keeping officer?

A

ECDIS

162
Q

What is the most complex system on the bridge?

A

ECDIS

163
Q

ECDIS equipment consists of

A

Hardware
Operating software
Digital hydrographic data in the form of ENC
ALPHA numeric info

164
Q

When did the IMO define performance standards for ECDIS?

A

1995

165
Q

IHO

A

International Hydrographic Organization

166
Q

IEC

A

International Electrotechnical Commission

167
Q

S-57/S-100

A

Transfer protocol

168
Q

S-61

A

Raster nav charts

169
Q

S-52

A

Specs for content and display

170
Q

S-63

A

Encryption

171
Q

S-64

A

Testing standards

172
Q

ECDIS MUST BE WIRED TO

A

GPS, gyrocompass, speed and distance measuring device

173
Q

What are the two ways to back up an ECDIS

A

Second ECDIS

Paper charts

174
Q

How long can power be interrupted without reinitializing the ECDIS?

A

45 seconds

175
Q

ENC charts are also called

A

Vector charts

176
Q

What charts are required by ECDIS?

A

ENC

177
Q

A single vector chart is called a

A

Cell

178
Q

Raster data files tend to be

A

Large

179
Q

Raster charts cannot take the place of

A

Paper charts

180
Q

If an ECDIS uses raster charts it operates in the

A

ECS mode, And you must have a paper chart back up for that area

181
Q

MRA

A

Mutual recognition agreement

182
Q

What are the 2 ECDIS training types?

A

Generic and equipment specific

183
Q

Compliance with regulatory ECDIS requirements will be checked by

A

Port state control

184
Q

The level of proficiency necessary for proper performance of the ECDIS functions on board a ship

A

Standard of competence

185
Q

Raster

A

Scanned and passive image of a paper chart

186
Q

Vector

A

Interactive chart reacting to digital analysis by object

187
Q

Where is RNC permitted?

A

Only were no official vector chart exists

188
Q

WGS 84

A

World Geodetic System

Standard for use in cartography geodesy and navigation

189
Q

IMO requires

A

North up presentation

190
Q

Ship and targets motions are based on sensors that deliver course through the water and speed through water

A

Water stabilized

191
Q

Route monitoring is used in

A

Ground stabilized mode

192
Q

Collision avoidance must be used in

A

Water stabilized mode

193
Q

What occurs when ENC is displayed at a larger scale than intended by the compilations scale

A

Over scaling

194
Q

Minimum level of chart info that has to be displayed

A

Base display

195
Q

Base display is not designed for

A

Navigation

196
Q

Common mode for route planning and route monitoring and contains minimum required information for navigation

A

Standard display

197
Q

Shows all info relating to chart

A

All display

198
Q

What are the three levels of display for system information

A

Base, standard, full

199
Q

SCAMIN

A

Scale minimum

Sets the scale below that an object no longer be displayed on the screen automatically

200
Q

ECDIS Can be viewed as

A

Primary or secondary display

201
Q

What are the 2 available color schemes?

A

Two depth shades

Four depth shades

202
Q

Line between navigable and unnavigable sea areas

A

Safety contour

203
Q

Dark blue

A

Shallow waters

204
Q

Medium blue

A

Risk of grounding

205
Q

Light blue or grey

A

No danger of grounding, but other restrictions can limit speed

206
Q

White

A

Very deep waters no sailing restrictions

207
Q

What is selected by the murdered provide a more clear indication of unsafe spot soundings

A

Safety depth

208
Q

Bathymetric inlays

A

Present a more accurate presentation of under water features

Radar (1 decks)

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