Radar-Arpa Operators Manual Controls(1)

5/26/2018 Radar-Arpa Operators Manual Controls(1)

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OPERATIONAL INSTRUCTIONS FOR

NUCLEUS MODEL

2.1 SYSTEM OPERATION2.1.1 Design & OperationThe equipment is designed as either a mounted Console or desk display with separateprocessor cabinet.Using the mouse, the trainee can operate all functions. The Radar/ARPA simulator computerand monitor must be switched on to start the simulator, the simulation program must be startedand a simulation scenario loaded on the Instructor station.

2.2 START UP2.2.1

Simulation Start up Sequence for Radar/ARPA

Once the Radar Application is launched, click Standby box to initialise the Radar. The Text inthe box changes to Ready. (Refer Fig-1)

Fig-1: Ready / Standby

To initialize the RADAR click onStandby in this box until textchange to Ready.


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ARI -RADAR ARPA OPERATOR S MANUAL

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2.3 DISPLAY AND SCREEN CONTROLS

Fig-2: Picture of Radar displaying screen controls

2.3.1 Ready / Standby

To initialise the radar click Standbyas explained in section 2.2.1 to come to Ready mode andto pause the radar click Ready to come to Standby mode.Keep the radar on Standbymode prior to stopping the radar system.


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AR I -RADAR ARPA OPERATOR S MANUAL

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VISIT US: WWW.ARISIMULATION.COM CONTACT US: [email protected]

This document is confidential and the property of ARI Pvt. Ltd

2.3.2 ModeThe radar can be operated in 2 motions (Relative Motion and True Motion)and in 3 modes(North Up, Head Up and Course Up). However in true motion only north-up mode can be used.

Fig-3: Setting the Radar mode

2.3.2.1 RELATIVE MOTION

ExplanationA Relative Motion(RM) display is one in which a stationary spot (called the origin or electronic

center) represents the position of the own vessel, while all targets move relative to the centeracross the radar screen.The relative movement of each target on the radar screen is the resultant of actual course /speed of target and course / speed of own vessel. For example a stationary targets on radarscreen (with Relative Motion) would appear to move with a course (opposite to own vessel)and speed of own vessel.The origin is normally at the center of the radar screen but may be shifted to off-centerposition.Method of OperationRelative Mode is the default mode during start up. Click on the box as shown in Fig tochange to Relative Motionfrom True Motion.

2.3.2.2 NORTH UP

North Up

Course Up

Select type of mode for display

Select type of motionfor display


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Explanation

North Up mode is an azimuth-stabilized presentation, with the ships heading fed fromGyrocompass.Here the zero of the fixed scale of the Radar Plan Position Indicator (PPI) represents the True

North and the heading marker represents the true course of own ship. All bearings of targetsare true.As the own ship alters course the heading marker swings around to the new course on theradar PPI but all targets remain at their true bearings.Targets on a parallel course and at the same speed appear stationary, while fixed targetsproduce trails that represent the reciprocal of own ships ground track.When course fed from gyrocompass fails (if such fault is induced from the instructor station) theradar mode automatically changes to head-up mode. HDGxxx is indicated.Method of OperationNorth Up mode is the default mode at start up. Click on the box as shown to switch betweenNorth Up, Head Upand Course Up.

2.3.2.3

HEAD UP

Explanation

In Head Upmode the 12 oclock position of the Radar PPI always represents the ships courseand hence the heading marker remains at the zero of the fixed, graduated ring around theRadar PPI. All bearings are relative.The right side of the radar screen is the starboard side of the ship and the left side of theradar screen is the port side of the ship. At the instant of measuring the bearing of a target,the ships heading must be noted exactly.The sum of the relative bearing and the true course at that instant gives the true bearing of thetarget, if all are expressed in the three-figure notation. If the sum exceeds 360, then 360 mustbe subtracted from the sum.As the course is changed, the heading marker remains fixed while all the targets swing around

to their new relative bearings.No bearings can be obtained accurately during the alteration, and should be taken when thenew picture gets painted clearly after the Radar PPI is refreshed.Method of OperationClick on the box as shown to change to Head Up mode.

2.3.2.4 COURSE UP

ExplanationCourse Up is an azimuth-stabilized presentation, available in relative mode with the shipsheading aligned to 000 degrees on the bearing scale at the time that the mode is selected.Subsequent alterations in course result in the Heading Line (HL) deviating from 000 degrees,but the picture does not rotate. The ships Heading Line (HL) is course stabilized, such that, ifown ship yaws, targets maintain direction. The ships Heading Line (HL) may be updated atany time by further selecting Course Up, whereby the picture realigns on the new heading.Method of OperationClick on the box as shown to change to Course Upmode.

Course Up


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2.3.2.5 TRUE MOTION2.3.2.6 EXPLANATIONTrue motion is an azimuth and speed stabilized mode. It gets its compass feed from thesimulated gyrocompass and speed feed from the simulated Doppler log and GPS (Global

Positioning System).If speed input is from log, then the mode is True motion - Sea stabilized and when thespeed input is from GPS (Global Positioning System), then the mode is True motion - Groundstabilized.The display is in a True Motion mode with own ship positioned off-center and moving in thedirection of the Heading Line at true speed, normally through the center of the display. Alltargets move on screen with true courses, speed and target trails.

Own ship course changes do not affect targets direction, but the Heading Line reflects thechanges in own ship course. Any targets on a collision course with own ships are on a constantbearing with a decreasing range.Method of Operation

Click on the box as shown to change to True Motion from Relative Motion. For TrueMotion North Up mode is set by default.

2.3.3 Radar / Pulse Length2.3.3.1 X BAND & S BAND

X Band and S Band are the two bands at which radar can operate. X Band radar has awavelength of 3cm and S Band radar has a wavelength of 10cm.Method of OperationTo switch betweenX Bandand S Bandclick in box as shown in the fig

2.3.3.2 PULSE LENGTHExplanationPulse Length (PL): It is the time taken for a pulse to leave the scanner i.e. the interval betweenthe instant the leading edge of the pulse leaves the scanner and the instant the trailing edgeof the pulse does so.

Pulse Length (PL) is usually expressed in microseconds. As the speed of radio waves is 300meters per microsecond, Pulse Length (PL) may also be expressed in meters. Pulse Length (PL) isalso referred to as Pulse Width (PW) and is controlled by the transmitter.When an echo returns from a target, it will be the same length as the pulse. When the leadingedge of the echo enters the receiver, the tracing spot on the radar screen start painting andbecomes fat / bright and remains so until the entire echo comes in. When the trailing edge ofthe echo has come in, the tracing spot reduces back to its original size.The tracing spot becomes a blip (referred to as paint) for a time interval equal to Pulse Length(PL). During this time interval the blip / paint would have covered a distance equal to half thePL in meters, on its steady & radial path (its scale speed is half that of radio waves). The blip/ paint on the PPI would hence appear to have a radial depth equal to half the PL in meters.

Selection of Xor SBand


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To ensure range accuracy, the tracing spot is synchronized with the leading edge of the pulse.The correct range of a target is indicated by the range of the nearest edge of its paint on thescreen.Pulse Length (PL) does not affect range accuracy and range discrimination. However short

pulses are suitable for the shorter-range scales as they give better range discrimination.To cover longer ranges long pulses would have to be sent out, to allow for attenuation (loss ofenergy) in the atmosphere. Long pulses would be unsuitable for short ranges because alltargets painted on the radar screen would appear too large in the radial direction and paint/ blip created by echoes from sea waves and rain drops would be specially troublesome (asthere would be considerable overlapping of such paint / blip on the radar screen).The radar has three values of Pulse Length (PL), which changes automatically when the rangescale selector switch is operated.

The Pulse Length (PL) in micro seconds that is available is given below:

POSITION OF PL SELECTOR

SWITCH

SHORT RANGE

SCALES (3 M & LESS)

MEDIUM RANGESCALES (6 & 12

M)

LONG RANGESCALES (24, 48 & 96

M)

SHORT .05 .25 .75

LONG .25 .75 1.0

2.3.4 Tuning

ExplanationThe Tuningcontrol is provided to manually change the frequency of the Local Oscillator (LO)so as to bring the frequency of the Intermediate Frequency (IF) signals to the desired value

required by Intermediate Frequency (IF) amplifier.Tuning is adjusted while watching the PPI. The tuning indicator shows the level of tuning,maximum tuning lit all the eight LEDs. Correct tuning is attained when maximum & clear targetechoes or clutter echoes are seen or when the length of the performance monitor signal isgreatest. Alternately, center the magic eye box at the center of its width for optimal results.

Method of OperationIn order to increase or decrease Tuning, click right or left hand side respectively of the boxmarked T as shown in Fig- OR -Click > on top bar in menu control window till the menu Tuning/Gainis highlighted.Click Tuningfrom the listed variables and click +/- (in the bottom bar) in order to increaseor decrease the tuning parameter value.

Turing


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The radar is best tuned when magic eye is lit till the indicator line.

2.3.5 Gain

Explanation

Gain controls the amplification of all received echoes. It sets the threshold value of radarsignals displayed on the screen. The gain is to be advanced until an even speckledbackground is just visible on the screen.

a. Too high setting of Gain control results in poor quality radar picture masked byexcessive noise.

b. Too low setting of Gain control results in loss of weak targets and reduction indetection range.

Note: Gain control should not be set too high as excess noise on the radar screen degrades thepicture quality.In order to set optimum Gain control set the slider on the top left most corner to the centerposition.Method of OperationIn order to increase or decrease Gain click right hand side or left hand side respectively ofthe box marked G as shown in Fig.- OR -Click > on top bar in menu control window till the menu Tuning/Gain is highlighted.Click Gainfrom the listed variables and click +/- (in the bottom bar) in order to increase ordecrease the gain parameter value.

2.3.6 Sea Clutter

Explanation

The Sea Clutteror the Sensitivity Time Control (STC) is a manual adjustment that reduces seaclutter returns/echoes. Maximum attenuation takes place at zero range until no reduction ofsignals or clutter occurs at a maximum range of 6 miles.Advancing the sea setting progressively reduces the near range clutter. The sea level may be

set from minimum to maximum with a typical operational level at medium level. Less sea is tobe applied on short pulse and more sea is to be applied on long pulse.The correct setting for sea under any given condition is only obtained by experience. Too highsetting of sea clutter may result in the loss of close range targets. Never set the sea control toclear all clutter, but leave a light speckle of sea returns to indicate optimum sensitivity withinthe clutter field.If the sea clutter control is not in use it should always be set to zero.Method of OperationIn order to increase or decrease Sea Clutter suppression, click right or left hand siderespectively of box marked S as shown in Fig.- OR -Click > on top bar in menu control window till the menu Anti Clutter is highlighted.


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Click Sea Clutter Supp Powerfrom the listed variables and click +/- (in the bottom bar) inorder to increase or decrease the sea clutter suppression parameter value.

2.3.7 Rain Clutter

Explanation

This control is also called Fast Time Constant (FTC) or anti rain clutter. Rainfall areas show upfairly well on the PPI. However, where the rainfall is heavy, the rain echoes saturate that partof the PPI such that the targets tend to get drowned or swamped in the rain echoes.This function uses the received radar signals to produce a threshold reference level. The raincontrol moves the threshold reference level so as to apply more or less attenuation to theradar signal.

When using this function RACON responses are also likely to be suppressed. The rain cluttersuppression level may be set from minimum to maximum with a typical operational level atmiddle level.When not in use the RAIN control is always to be set to minimum.The rain setting is to be adjusted to preserve small targets. It is often beneficial to reduce theGAIN setting slightly to optimize target detection in high precipitation.Method of OperationIn order to increase or decrease Rain Clutter suppression, click right or left hand siderespectively of box marked R as shown in Fig- OR -Click > on top bar in menu control window till the menu Anti Clutter is highlighted.Click Rain Clutter from the listed variables and click +/- (in the bottom bar) in order toincrease or decrease the rain clutter suppression parameter value.

2.3.8 Range / Rings

Fig-4: Range and Range Rings


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2.3.8.1 RANGEExplanationThe displayed range may be changed from 0.25nm to 48nm in fixed range steps of 0.1250.25nm, 0.5nm, 0.75nm, 1.5nm, 3nm, 6nm, 12nm , 24 nm, 48nm and 96nm

Method of OperationIn order to increase or decrease the Range right click or left click respectively on the box asshown in Fig- OR -Click > on top bar in menu control window till the menu Range is highlighted.Click Range from the listed variables and click +/- (in the bottom bar) in order to increaseor decrease the range parameter value.

2.3.8.2 RINGSExplanationRange rings can be displayed for each range selected and scaled according to the range in

use.

S.NO.RANGE

(NM)

NO. OF

RINGS

DISTANCE BETWEEN

RINGS (NM)

1 0.125 6 0.021

2 0.25 6 0.042

3 0.5 6 0.083

4 0.75 6 0.125

5 1.5 6 0.25

6 3 6 0.5

7 6 6 1.08 12 6 2

9 24 6 4

10 48 6 8

11 96 6 16

Method of OperationSwitching range rings on/offIn order to switch the range rings on/off, click on the box as shown in Fig.- OR -

Click > on top bar in menu control window till the menu Range is highlighted.Click Rings On/Off from the listed variables and click toggle state (in the bottom bar) inorder to switch the ring on/off.

2.3.9 Target AcquisitionExplanation

This function allows the user to acquire targets and display information about the targetrelative to the vessel. There are two methods of acquiring targets.


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They are as follows: -

ACQUIRING TARGETS MANUALLYLeft click the target that needs to be acquired. A plus appears over the target symbolizingthat the acquisition is in process. Once the target acquisition process completes, the symbol on

the target changes and the target is allotted a number. Right click on the acquired targetdisplays the target information in a separate window, which appears on the lower right handside corner as shown in Fig-2 . Left click on the acquired target deselects the acquired targetmanually.

ACQUIRING TARGETS AUTOMATICALLY

In order to acquire targets automatically, left click the Auto Acquire box as shown in Fig-2 . Alltargets that appear on the PPI are acquired automatically and given a number. Right click onthe acquired target displays the target information in a separate window, which appears onthe upper right hand side corner. Left click the Auto Acquire box again to switch off the autoacquire mode.

Fig-5: Auto-acquire ON/OFF

2.3.10Auto Sea Clutter

Fig-6: Auto-clutter ON/OFF

ExplanationAuto S Clutter is used to adjust the sea clutter automatically.Method of OperationIn order to use the Auto S Clutter facility click the box as shown in Fig to switch the autoclutter mode ON/OFF.- OR -Click > on top bar in menu control window till the menu Anti Clutter is highlighted.

Click Auto S Clutter On/Off from the listed variables and click toggle state (in the bottombar) in order to switch the Auto clutter mode ON/OFF. When working in auto mode a textAUTO is displayed in the respective box in the left hand top corner

2.3.11AlarmsMethod of OperationAlarms sound automatically based on settings for Closest Point of Approach (CPA), Time ofClosest Point of Approach (TCPA), loss of sensor input such as Log, Global Positioning System(GPS) etc.An alarm sounds on the speakers fitted to the ARI Radar/ARPA simulator and the ALARM boxon the PPI turns red. The cause of alarm is noted in yellow on the top part of the PPI.In order to acknowledge the Alarm, click on the red Alarm box as shown in Fig-2

Click here to useAuto Sea Clutter.

Click here toacquire targetsautomatically.


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The alarm message is displayed in the area marked as shown in Fig-2 .

If there are multiple alarms, clicking on the ALARM box will acknowledge one alarm with thealarms appearing in reverse order of occurring with the latest alarm showing first.

Following is the list of alarms that are triggered in the radar.

S.NO. ALARM MESSAGE OCCURRENCE

1. Object in GuardZone

When any dangerous object enters guard zonemarked around the vessel

2. No Speed Source When speed sources from Doppler and GPS are notavailable.

3. No ground speedsource

When ground speed input from GPS not available

4. No sea speed source When sea speed input from Doppler not available5. No Heading input When heading information from Gyro is not

available.6. Target Proximity When a target is within CPA / TCPA limit that is set7. Gyro Heading input

lost.When Heading information from Gyro is notavailable

8. GPS position inputlost.

When position information from the GPS notavailable

9. GPS SOG input lost When ground speed input from GPS not available10. LOG SOG input lost When speed over ground input from Doppler not is

available.11. LOG SOW input lost When speed over water input from Doppler not is

available.12. No GPS ground

speed input.When ground speed input from GPS not available

13. No GPS positioninput

When position information from the GPS notavailable

14. No LOG groundspeed input.

When speed over ground input from Doppler not isavailable.

15. No LOG sea speedinput.

When speed over water input from Doppler not isavailable.

16. No Gyro Headinginput

When Heading information from Gyro is notavailable

17. Self-Diag. Done. No

error.

When self-diagnostic test is completed successfully.


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2.3.12Own-Ship / Tracking Data

Fig-7: Own ship Tracking Data

2.3.12.1HEADINGExplanationDisplays own ship heading. This is provided by the simulated gyrocompass. When the Instructorenters a gyro error, a positive error fed in increases the visible gyro position by the number ofdegrees entered while a negative error provides the reverse effect.

2.3.12.2SPEEDExplanationThe normal displayed speed is ships speed taken from one of three sources; vessels GlobalPositioning System (GPS), LOG or manually (MAN) input speeds.

Fig-8: Auto/ Manual

Method of Operation - Manual speed settingIn order to change the vessels Speed click on speed in box as shown in Fig.Click > on top bar in menu control window till the menu Set/Drift/Speed ishighlighted.Click Auto/Manual from the listed variables and click toggle state (in the bottom bar) tomake the input Manual.


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Click Up/Down from the listed variables and then click +/- (in the bottom bar) to increase ordecrease own ships speed as desired.- OR -Click > on top bar in menu control window till the menu Set/Drift/Speed ishighlighted.Click Auto/Manual from the listed variables and click toggle state (in the bottom bar) tomake the input Manual.Click Select from the listed variables and click toggle state (in the bottom bar) to selectspeed option as shown in Fig.Click Up/Down from the listed variables and then click +/- (in the bottom bar) to increase ordecrease own ships speed as desired.

2.3.12.3STABILIZATIONSea stabilization:Sea stabilization gives the correct heading and speed through the water. No set and driftinformation is used (no drift or set/rate). It provides an excellent display for Anti - Collision.

The true trails of targets give an indication of their apparent true motion.A single axis log (or manual speed input) and gyro provide sensor data for the stabilization.Ground stabilizationThe radar receives course made good and speed made good inputs from the GPS. This takeseffect when the GPS is in ground-stabilized mode.

Fig-9: Ground Stabilized Mode

Method of Operation - Log and GPS stabilizationThe user can toggle between Radar stabilized to Logor GPS by clicking on column STAB

in the box as shown in Fig to select SEA / GND state. The switch will happen only if therequired equipment is switched on and connected.

2.3.12.4OWN-SHIP POSITIONWhen the Global Positioning System (GPS) is switched on and connected, own ship position isdisplayed as shown in Fig . If the GPS feed is not available, xxxxxx is displayed on thelocation where the position is displayed.

2.3.12.5VECTORSThe vector indicates the predicted direction and speed of the tracked targets (either True orRelative). The vector is shown as a solid line, proportional to the speed of the target (i.e. with

15 minute vector selected, a target speed of 12kts produces a vector line length of threemiles). The vector can be shown in reverse mode i.e. True vector in Relative Motion or Relativevector in True motion.


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2.3.12.5.1TYPES

Method of OperationTo switch between Trueand Relative Vector Mode click on the box as shown in Fig.

2.3.12.5.2TIME

Fig-10: Vectors Menu

Method of OperationClick > on top bar in menu control window till the menu Vectors is highlighted.Click Vector Length from the listed variables and click +/- (in the bottom bar) in order toincrease/decrease vector time.

2.3.12.5.3TRAILSExplanationThe previous True track of targets is displayed as trails. The length of the trails can bechanged (three minutes is the normal default value) or it can be switched OFF. This feature canbe activated when GPS feed is available.

Method of OperationLeft click on the box as shown in Fig to switch on the Trails.Click > on top bar in menu control window till the menu Vectors is highlighted.Click Trail Length from the listed variables and click +/- (in the bottom bar) in order toincrease/decrease trail length.

Relative


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2.3.12.6CPA/TCPAExplanationThe Closest Point of Approach(CPA) is the point where the range of the target would be theminimum, provided both (own ship and target) maintain the courses and speeds that they had

during the plotting interval. The range at Closest Point of Approach (CPA) is also called`Nearest approach.

Fig-11: Display of CPA / TCPA Limit

2.3.12.6.1CPALIMITThis function helps by warning the operator that a target is approaching within the designateddistance and that the evasive action is to be taken. The CPA limit is selected and then adjustedto suit the manoeuvrability of the ship and the prevailing conditions.Method of OperationClick > on top bar in menu control window till the menu CPA/TCPA is highlighted.Click CPA Limit Up/Down from the listed variables and click +/- (in the bottom bar) inorder to increase/decrease CPA limit.Dangerous Target Alarm: If CPA and TCPA of a target are less than CPA and TCPA limits setby user, then dangerous target alarm sets on and a blinking triangle mark red in color isshown near the vector.

2.3.12.6.2TCPALIMITExplanationThis function provides a warning to the operator that a target may cause possible danger ifthe avoiding action is not taken within the set time.Method of OperationClick > on top bar in menu control window till the menu CPA/TCPA is highlighted.Click TCPA Limit Up/Down from the listed variables and click +/- (in the bottom bar) inorder to increase/decrease TCPA limit.

2.3.12.7SET / DRIFT / SPEED

Fig-12: Set / Drift / Speed

2.3.12.7.1SETExplanationSetis provided to counteract the effects of current and wind. Set input is entered manually.Method of OperationIn order to change the Set parameter, click on set in box as shown in FigClick > on top bar in menu control window till the menu Set/Drift/Speed ishighlighted.Click Auto/Manual from the listed variables and click toggle state (in the bottom bar) tomake the input Manual.


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Click Up/Down from the listed variables and then click +/- (in the bottom bar) to increase ordecrease the Set parameter as desired.- OR -Click > on top bar in menu control window till the menu Set/Drift/Speed ishighlighted.Click Auto/Manual from the listed variables and click toggle state (in the bottom bar) tomake the input Manual.Click Select from the listed variables and click toggle state (in the bottom bar) to select setoption.Click Up/Down from the listed variables and then click +/- (in the bottom bar) to increase ordecrease the Set parameter as desired.

2.3.12.7.2 DRIFTExplanationDriftis provided to counteract the effects of current and wind. Drift input is entered manually.Method of OperationIn order to change the Drift parameter, click on drift in box as shown in Fig .

Click > on top bar in menu control window till the menu Set/Drift/Speed ishighlighted.Click Auto/Manual from the listed variables and click toggle state (in the bottom bar) tomake the input Manual.Click Up/Down from the listed variables and then click +/- (in the bottom bar) to increase ordecrease the Drift parameter as desired.- OR -Click > on top bar in menu control window till the menu Set/Drift/Speed ishighlighted.Click Auto/Manual from the listed variables and click toggle state (in the bottom bar) tomake the input Manual.Click Select from the listed variables and click toggle state (in the bottom bar) to select drift

option.Click Up/Down from the listed variables and then click +/- (in the bottom bar) to increase ordecrease the Drift parameter as desired.

2.3.12.7.3SPEEDExplanationThe normal displayed speed is ships speed taken from one of three sources i.e. vessels LOG(sea stabilization), GPS (ground stabilization) or manually (MAN) input speeds. A single axislog or manual speed input will give speed relative to sea. A Doppler log (X-Y axis) will givespeed over the seabed.Method of OperationIn order to change the vessels Speed click on speed in box as shown in Fig .Click > on top bar in menu control window till the menu Set/Drift/Speed ishighlighted.Click Auto/Manual from the listed variables and click toggle state (in the bottom bar) tomake the input Manual.Click Up/Down from the listed variables and then click +/- (in the bottom bar) to increase ordecrease own ships speed as desired.- OR -Click > on top bar in menu control window till the menu Set/Drift/Speed ishighlighted.Click Auto/Manual from the listed variables and click toggle state (in the bottom bar) tomake the input Manual.Click Select from the listed variables and click toggle state (in the bottom bar) to selectspeed option as shown in Fig .


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Click Up/Down from the listed variables and then click +/- (in the bottom bar) to increase ordecrease own ships speed as desired.

2.3.13Menu ControlsThe radar menu control is the window that is at the lower right hand side of the radar screen.There are three parts of the menu control window.

Fig-13: Menu Control

Top bar: The menu field bar with > on either side, which is used to move to theprevious or next group of available variables by left click of the mouse.Middle bar: Menu variables are displayed in the middle bar. The selected item from amongstthe group is highlighted in red.Bottom bar: The lower bar is the control panel where left clicking +/-, toggle orincrease/decrease can change variable parameters.

2.3.13.1TUNING / GAIN

Fig-14: Tuning/Gain

Menu Control


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2.3.13.1.1TUNINGMethod of OperationClick > on top bar in menu control window till the menu Tuning/Gain is highlighted.Click Tuning from the listed variables and click +/- (in the bottom bar) in order to increase

or decrease the tuning parameter value.

2.3.13.1.2GAINMethod of OperationClick > on top bar in menu control window till the menu Tuning/Gain is highlighted.Click Gain from the listed variables and click +/- (in the bottom bar) in order to increase ordecrease the gain parameter value.

2.3.13.1.3 DAY/NIGHTMethod of OperationClick > on top bar in menu control window till the menu Tuning/Gain is highlighted.

Click Day/Night Mode from the listed variables, click toggle state (in the bottom bar) toswitch the RADAR display between Day/Night modes.

2.3.13.1.4PARALLELINDEXLINESExplanationTo enable the operator to use Parallel Index Lines(P.I) as an aid to entering hazardous areas(e.g. estuary), the system provides four independent pairs of parallel linesParallel index technique is the art of manoeuvring a ship to a desired position or along adesired track, in such a manner that the entire manoeuvre is carried out while watching the PPIonly. The chart is consulted before hand and pre-computation is done, but no fixes are plottedon the chart during the transit period because continuous fixing is done on the PPI with the helpof the parallel index. Allowances for current and wind are made, as and when necessary,during the manoeuvre, by inspection of the ships progress on the PPI.

Method of OperationClick > on top bar in menu control window till the menu Tuning/Gain is highlighted.Click P.I. Lines On/Off from the listed variables and click toggle state (in the bottom bar) toswitch parallel Index line on/off.By switching ON the parallel index line, two parallel lines appear. One passes through theorigin of the own ship and the other can be set at an offset distance from the first line.


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2.3.13.1.5PARALLELINDEXADJUSTMENTMethod of OperationIn order to adjust the parallel index line, click > on top bar in menu control window tillthe menu PI Lines is highlighted. Click P.I. Lines On/Off from the listed variables.

A single PI Line at the center of the PPI will be displayed rotate this line to the desired angle.Click on PI line adj and drag the PI line to the required position on the radar PPI and left clickto permanently position the PI line there.In order to reset the PI line angle we need to switch off the PI line and switch it on again.There after follow the above procedure.4 sets of PI line are available and their information can be toggled in the PI line informationwindow by left/right clicking on the PI line number symbol.

Fig-15: Parallel Index Line Adjustment

2.3.13.2EBL / VRMExplanationThe Electronic Bearing Line (EBL) is used to measure the bearing of a target from own shipeither in True or Relative mode. When selected, the Electronic Bearing Line (EBL) is displayedas a line, originating from own ship to the outer edge of the Radar display. The bearing of thetarget is displayed in a box, located in the lower right-hand corner of the screen as shown inFig-2 .The Variable Range Marker (VRM) is used to measure the range of a target from own ship.When selected, the Variable Range Marker (VRM) is displayed as a dashed circle, thediameter of which is altered by use of the mouse. The range of the target is displayed in abox, located in the lower right-hand corner of the screen as shown in Fig


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EBL/VRM ERROR: The instructor can induce faults into the radar from the navigationequipments control panel by providing the inputs for EBL / VRM offset.

Fig-16: Parallel Index Line Adjustment

EBL / VRM 1 ADJUST / PLACEMethod of Operation

In order to adjust the EBL/VRM1 click > on top bar in menu control window till themenu EBL/VRM is highlighted.Click EBL/VRM1Adj from the listed variables; click toggle state (in the bottom bar) to switchon and to activate adjustment of EBL/VRM1. Move the mouse on the PPI to adjust and placethe EBL/VRM1 as desired.

2.3.13.2.1EBL/VRM1OFFMethod of OperationIn order to switch off EBL/VRM1 click > on top bar in menu control window till themenu EBL/VRM is highlighted.Click EBL/VRM1 Off from the listed variables and click toggle state (in the bottom bar) toswitch off EBL/VRM1.Alternate Method of placing and releasing EBL / VRM1:There is another method also available to user to place EBL/VRM1.Left click the box named EBL1/VRM1 located at the lower right hand side corner of the PPI asshown in Fig . The text changes from OFF to values in the respective columns.Move the mouse pointer on PPI to fix the EBL/VRM1 position to the desired spot and left clickto set EBL/VRM1 to that position.To switch off the EBL / VRM1 left click the same box again.

2.3.13.2.2EBL/VRM2PLACE/ADJUSTMobile EBL (offset EBL)

The EBL may be offset and used to measure the bearing of a target from a point on the screenother than own ship.Dual Movement of the VRM / EBLThe VRM and EBL may be selected to move simultaneously to enable the combinedmeasurement of range and bearing of an echo from own ship. If the EBL is offset, the facility isused to measure the distance and bearing of one target with respect to another target.Method of OperationIn order to place EBL/VRM2 click > on top bar in menu control window till the menuEBL/VRM is highlighted.Click EBL/VRM2 Place from the listed variables and click toggle state (in the bottom bar) toswitch on and place EBL/VRM2. Move the mouse on the PPI and click on the selectedspot/target to place EBL/VRM2. Click again to set the EBL/VRM2.


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2.3.13.2.3EBL/VRM2ADJUSTMethod of OperationIn order to adjust EBL/VRM2 click > on top bar in menu control window till the menuEBL/VRM is highlighted.

Click EBL/VRM2 Adj from the listed variables and click toggle state (in the bottom bar) toactivate adjustment of EBL/VRM2. Move the mouse on the PPI and click to set the EBL/VRM2as desired.

2.3.13.2.4EBL/VRM2OFFMethod of OperationIn order to switch off EBL/VRM2 click > on top bar in menu control window till themenu EBL/VRM is highlighted.Click EBL/VRM2 Off from the listed variables and click toggle state (in the bottom bar) toswitch off EBL/VRM2.Alternate Method of placing and releasing EBL / VRM2:There is another method also available to user to place EBL/VRM2.

Left click the box named EBL2/VRM2 located at the lower right hand side corner of the PPI asshown in FigA message Place the Floating EBL center comes in the box above.Move the mouse pointer on PPI and left click to fix the EBL/VRM2 center to the desired spot.Left click again to set EBL/VRM2 to required position.To switch off the EBL / VRM2 left click the same box again.

2.3.13.2.5EBL3ADJUST/OFFMethod of OperationIn order to switch On/Off & adjust EBL3 click > on top bar in menu control window tillthe menu EBL/VRM is highlighted.Click EBL3 Adj/Off from the listed variables and click toggle state (in the bottom bar) toswitch on EBL3. Move the mouse on the PPI to adjust EBL3, click to set the EBL3 as desired.

Click again on EBL3 Adj/Off toggle state (in the bottom bar) to switch off EBL3 when notrequired.

2.3.13.3MISCELLANEOUS2.3.13.3.1EBL/VRMBRILLIANCEThis control adjusts the brilliance of EBL / VRM.Method of OperationIn order to adjust the EBL/VRM brilliance click > on top bar in menu control window tillthe menu Misc is highlighted. Click EBL/VRM Brilliance from the listed variables and click+/- (in the bottom bar) to increase/decrease the EBL/VRM Brilliance.

Fig-17: Figure showing the miscellaneous Menu


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2.3.13.3.2PERFORMANCEMONITORExplanationPerformance Monitor is available at 1.5 NM Range and it checks the overall performance ofthe Transmitter/Receiver System by displaying the Radar transmission and receiver response

(SUN) at the center of the display. During installation the Radar Performance is measured toestablish a performance reference level.The instructor can inject a fault by reducing the percentage of the Performance monitor plume.Method of OperationClick > on top bar in menu control window till the menu Misc is highlighted.Click Perf Monitor from the listed variables and click toggle state (in the bottom bar) to startperformance monitor. Click toggle state (in the bottom bar) again to stop it.

2.3.13.3.3HEADINGMARKERMethod of OperationClick > on top bar in menu control window till the menu Misc is highlighted.Click Heading Marker from the listed variables and click toggle state (in the bottom bar) to

activate and switch off Heading Marker.It remains off for a period till the user keeps toggle state pressed. Heading Marker becomesvisible the moment toggle state (in the bottom bar) is released.

2.3.13.3.4DATABRILLIANCEMethod of OperationClick > on top bar in menu control window till the menu Misc is highlighted.Click Data Brilliance from the listed variables and click +/- (in the bottom bar) toincrease/decrease the data brilliance.

2.3.13.4VECTORS

Fig-18: Vectors

Explanation

The vector indicates the predicted direction and speed of the tracked targets (either True orRelative). The vector is shown as a solid line, proportional to the speed of the target (i.e. with15 minute vector selected, a target speed of 12kts produces a vector line length of threemiles). The vector can be shown in reverse mode i.e. True Vector in Relative Motion or RelativeVector in True Motion.


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2.3.13.4.1VECTORLENGTHMethod of OperationClick > on top bar in menu control window till the menu Vectors is highlighted.Click Vector Length from the listed variables and click +/- (in the bottom bar) in order to

increase/decrease vector time.2.3.13.4.2TRAILLENGTHExplanationThe previous track of targets (True) is displayed as trails on the radar screen. The length of thetrails can be changed (three minutes is the normal default value) or trails can be switched off ifnot required.Method of OperationLeft click on the box as shown in Fig to switch on the Trails.Click > on top bar in menu control window till the menu Vectors is highlighted.Click Trail Length from the listed variables and click +/- (in the bottom bar) in order toincrease/decrease trail length.

2.3.13.5GUARD ZONE

Fig-19: Guard Zone and Suppression Zone

Method of operation

To activate and operate the guard zonesand suppression zones, click on the box as shownin Fig. Highlight GZ1, GZ2, SZ in order to operate the same.

Fig-20: Guard Zones

Following functions can be used only if guard zone is kept switched on.


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2.3.13.5.1THETAExplanationUsing the zone theta menu user can alter guard zone and suppression zone sectors. The guardzone inner and outer radius menus are used to vary the limits of the guard zones using the +/-

controls.Method of OperationClick > on top bar in menu control window till the menu Guard Zone is highlighted.Click Zone Theta from the listed variables and click +/- (in the bottom bar) in order toincrease/decrease Zone Theta.

2.3.13.5.2 INNERRADIUSMethod of OperationClick > on top bar in menu control window till the menu Guard Zone is highlighted.Click Inner Radius from the listed variables and click +/- (in the bottom bar) in order toincrease/decrease Inner Radius.

2.3.13.5.3OUTERRADIUSMethod of OperationClick > on top bar in menu control window till the menu Guard Zone is highlighted.Click Outer Radius from the listed variables and click +/- (in the bottom bar) in order toincrease/decrease Outer Radius.

2.3.13.5.4THETAOFFSETMethod of OperationClick > on top bar in menu control window till the menu Guard Zone is highlighted.Click Theta Offset from the listed variables and click +/- (in the bottom bar) in order to re-orient the guard zone clockwise or anticlockwise.

2.3.13.6ARPA

Fig-21: ARPA

2.3.13.6.1CANCELALLACQUISITIONThis control allows cancellation of all acquired targets.Method of OperationIn order to cancel all acquired targets click > on top bar in menu control window tillthe menu ARPAis highlighted.Click Cancel All Aq from the listed variables and click toggle state (in the bottom bar) tocancel all acquired targets.


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2.3.13.6.2TARGETPASTPOSITIONSThis control allows the radar to plot past positions of all targets at interval of every oneminute for the history time period selected.Method of Operation

In order to switch on/off history for , click > on top bar in menu control window till themenu ARPA is highlighted. Click Past Position from the listed variables and click togglestate (in the bottom bar) to switch between Past Position On and Past Position Off.Adjust (+/-) the total time of past positions required and increment time step using the submenu as per the fig above.

2.3.13.7ANTI CLUTTERAnti clutter is used for clutter suppression sea and rain clutters.

Fig-22: Anti Clutter

2.3.13.7.1AUTOON/OFFAuto S clutter is used to suppress sea clutter automatically.Method of OperationIn order to use the Auto Clutter Control facility, left click the box as shown in Fig to switchbetween the auto clutter modes ON/OFF.- OR -Click > on top bar in menu control window till the menu Anti S Clutter is highlighted.Click Auto On/Off from the listed variables and click toggle state (in the bottom bar) inorder to switch the Auto clutter mode ON/OFF.

2.3.13.7.2SEACLUTTERSUPPRESSIONMethod of OperationIn order to increase or decrease Sea Clutter suppression, click right or left hand side

respectively of box marked S on left hand top corner on radar screen. .- OR -Click > on top bar in menu control window till the menu Anti Clutter is highlighted.Click Sea Clutter Sup from the listed variables and click +/- (in the bottom bar) in order toincrease or decrease the sea clutter suppression parameter value.

2.3.13.7.3RAINCLUTTERSUPPRESSIONMethod of OperationIn order to increase or decrease Rain Clutter suppression, click right or left hand siderespectively of box marked R as shown in Fig .- OR -Click > on top bar in menu control window till the menu Anti Clutter is highlighted.


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Click Rain Clutter from the listed variables and click +/- (in the bottom bar) in order toincrease or decrease the rain clutter suppression parameter value.

2.3.13.8RANGE2.3.13.8.1RANGEExplanationThe displayed radar range may be changed from 0.25nm to 48nm in fixed range steps of0.125, 0.25nm, 0.5nm, 0.75nm and then doubling up to 96nm.

Fig-23: Range

Method of OperationIn order to increase or decrease the Range, right click or left click respectively on the box asshown in Fig- OR -Click > on top bar in menu control window till the menu Range is highlighted.Click Range from the listed variables and click +/- (in the bottom bar) in order to increase

or decrease the range parameter value.2.3.13.8.2RINGSON/OFFMethod of OperationIn order to switch the Range rings on / off left click on the box as shown in Fig- OR -Click > on top bar in menu control window till the menu Range is highlighted.Click Rings On/Off from the listed variables and click toggle state (in the bottom bar) inorder to show / hide the range rings.

2.3.13.8.3RINGBRILLIANCEMethod of OperationClick > on top bar in menu control window till the menu Range is highlighted.

Click Ring Brilliance from the listed variables and click (+) in order to increase range ringbrilliance or (-) to decrease the range ring brilliance till it diminishes.


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2.3.13.9DISPLAY CENTERThis control allows display of own ship at center of RADAR PPI (Plan Position Indicator).

Fig-24: Display Centering

2.3.13.9.1OFFCENTREThis function allows offset display of own ship position towards left/right/top/bottom fromcenter of RADAR PPI (Plan Position Indicator).Method of OperationClick > on top bar in menu control window till the menu Disp Centering ishighlighted.Click Off Centre from the listed variables and click toggle state (in the bottom bar). Themouse pointer will be displayed as + mark on Radar PPI.Click at the desired position to display own ship in Offset mode.

2.3.13.9.2CENTERDISPLAYThis function allows center display of own ship position on RADAR PPI (Plan Position Indicator).Method of OperationClick > on top bar in menu control window till the menu Disp Centering ishighlighted.Click Centre Display from the listed variables and click toggle state (in the bottom bar) todisplay own ship at center of radar PPI.

2.3.13.9.3RESETAZCIRCLEINCOURSEUPDISPLAYMODEMethod of OperationClick > on top bar in menu control window till the menu Disp Centering ishighlighted.Click C UpReset Az Circle from the listed variables and click toggle state (in the bottombar) to reset Az circles.

2.3.13.9.4TMCENTERRESETExplanationWhile changing the center display, the center of PPI also gets offset. This control is used tobring back the center display exactly at the center of radar PPI.Method of OperationClick > on top bar in menu control window till the menu Disp Centering ishighlighted.Click TMCentre Reset from the listed variables and click toggle state (in the bottom bar) toexactly reset the center.


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2.3.13.10 SET / DRIFT / SPEED

Fig-25: Set/Drift/Speed

Explanation

This control is provided to counteract the effects of tide and wind; it is entered manually byinputting SET & DRIFT values.The ships speed displayed on radar PPI is taken from one of two sources, vessels LOG ormanually (MAN) input ships speed. The single axis log or manual speed input will give shipsspeed relative to sea. The Doppler log (X-Y axis) will give speed over the seabed.Method of OperationIn order to change the vessels Speed click on speed in box as shown .Click > on top bar in menu control window till the menu Set/Drift/Speedishighlighted.Click Auto/Manual from the listed variables and click toggle state (in the bottom bar) tomake the input Manual.Click Up/Down from the listed variables and then click +/- (in the bottom bar) to increase or

decrease own ships speed as desired.- OR -Click > on top bar in menu control window till the menu Set/Drift/Speedishighlighted.Click Auto/Manual from the listed variables and click toggle state (in the bottom bar) tomake the input Manual.Click Select from the listed variables and click toggle state (in the bottom bar) to selectspeed option as shown.Click Up/Down from the listed variables and then click +/- (in the bottom bar) to increase ordecrease own ships speed as desired.

2.3.13.10.1 AUTO/MANUALThis control allows the user to either select speed manually or automatically from log sensor.2.3.13.10.2 SELECTIt is used to toggle between SET, DRIFT and SPEED.

2.3.13.10.3 UP/DOWNIt is used to change the values of the selected option by clicking on the + or the -sign.


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2.3.13.11 CPA / TCPA

Fig-26: CPA/TCPA

ExplanationThe Closest Point of Approach (CPA) is that point where the range of the target from own shipwould be minimum, provided own ship and target maintain their courses and speeds during theplotting interval. The range at CPA is also called `Nearest approach.

2.3.13.11.1 CPALIMITUP/DOWNExplanationThis function warns the operator about the targets approach within the designated range limitand that an evasive action is to be taken by own ship. The CPA limit is adjusted to suit themanoeuvrability of the ship and the prevailing circumstances and conditions.Method of OperationClick > on top bar in menu control window till the menu CPA/TCPA is highlighted.

Click CPA Limit Up/Down from the listed variables and click +/- (in the bottom bar) inorder to increase/decrease CPA limit.

2.3.13.11.2 TCPALIMITUP/DOWNExplanationThis function provides a warning to the operator that a target (within a certain time) may causepossible danger if an avoiding action is not taken. The TCPA may be selected and thenadjusted as for the CPA.

Method of OperationClick > on top bar in menu control window till the menu CPA/TCPA is highlighted.Click TCPA Limit Up/Down from the listed variables and click +/- (in the bottom bar) in

order to increase/decrease TCPA limit.

2.3.13.11.3 TRIALMANOEUVRE


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Fig-27: Trial Manoeuvre

Explanation

This control allows the user to assess in advance, the consequences of the intended change ofcourse or speed by own ship in form of graphic display. It also allows planning of avoiding

action to be taken by own ship when a potential risk of collision exists with other target.When the trial manoeuvre feature is switched on, a red color T appears at the lower half ofthe radar PPI. All visual representation of actual processing is suspended. However the actualprocessing continue to take place in background and it is re-activated when trial manoeuvrefunction is switched off.Method of OperationClick > on top bar in menu control window till the menu Trial Manv is highlighted.Click Trial Manv from the listed variables and click toggle state (in the bottom bar) to starttrial manoeuvring, a red color T appears at the lower half of the radar PPI indicating startof trial manoeuvring. Computer takes the data mentioned in bar for computing during trialmanoeuvring. User can alter this data as described in later sections.Click toggle state (in the bottom bar) again to stop trial manoeuvring.

2.3.13.11.4 TRIALTIMESTEPMethod of OperationClick > on top bar in menu control window till the menu Trial Manv is highlighted.Click Trial TimeStep from the listed variables and click +/- (in the bottom bar) to increaseor decrease the trial time step as shown in Fig

2.3.13.11.5 TRIALCOURSESTEPMethod of OperationClick > on top bar in menu control window till the menu Trial Manv is highlighted.Click Trial Course Step from the listed variables and click +/- (in the bottom bar) to increaseor decrease the trial course step as shown in Fig .

2.3.13.11.6

TRIALSPEEDSTEPMethod of OperationClick > on top bar in menu control window till the menu Trial Manv is highlighted.Click Trial Speed Step from the listed variables and click +/- (in the bottom bar) to increaseor decrease the trial speed step as shown in Fig .


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2.3.14Guard Zone / Suppression Zone

Fig-28: Guard Zones

Explanation

The users can mark guard zones and suppression zones around their ownship such that whentargets such as other vessels, landmasses and buoys enter the zone; an alarm is raised and thetargets are highlighted. It allows navigators to maintain a safe distance from other objects.Suppression zones can be set around ownship to de-acquire targets. This is generally set asternof the ship, so that target behind own ship gets de-acquired providing free memory for othertargets. Targets in suppression zones cant be acquired manually or automatically.Note:Two guard zones are available. When a target, which has not been previously acquired,enters a guard zone, an alarm is raised and ARPA automatically acquires this target.Targets acquired within the guard zone cannot have their acquisition cancelled, until the guardzone is removed.Method of operationTo activate and operate under guard zones and suppression zones, click on the box asshown in Fig-2 .Highlight GZ1, GZ2, and SZ in order to operate on the same.

2.3.14.1GUARD ZONEOperating procedures already discussed earlier in section 2.3.13.5 in detail.

2.3.14.2SUPPRESSION ZONEOperating procedures already discussed earlier in section 2.3.13.5 in detail.

2.3.15EBL / VRM

Fig-29: EBL/VRM


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Explanation

EBL: The Electronic Bearing Line (EBL) is used to measure the bearing of a target from own shipeither in True or Relative mode. The EBL is displayed as a line, originating from own ship to theouter edge of the Radar display. The bearing of the target is displayed in a box, located in

the lower right-hand corner of the screen as shown in Fig .VRM: The Variable Range Marker (VRM) is used to measure the range of a target from ownship. The VRM is displayed as a dashed circle, the diameter of which is altered by use of themouse. The range of the target is displayed in a box, located in the lower right-hand corner ofthe screen as shown in Fig

2.3.15.1EBL 2 / VRM 2ExplanationMobile EBL (offset EBL): The EBL can be used in offset mode to measure the bearing of atarget from a point on the screen other than own ship. The EBL in offset mode is used tomeasure the bearing and distance of one target with respect to another.

2.3.16Spurious Echoes

There are various types of spurious echoes which are listed as follows: -

2.3.16.1MULTIPLE ECHOESWhen own ship is abeam of another moving object and within range of one mile, multipleechoes occur. These echoes are visible on the radar PPI and are plotted behind the target.

2.3.16.2INDIRECT ECHOESEchoes that occur by reflection of radar beam due to restricting objects are called indirectechoes. It occurs only in the blind sector.

2.3.16.3SIDE LOBE EFFECTWhen an object is within range of one mile of own ship, echoes that occur along the side of thetarget are termed as side lobe effect.

2.3.17RaconWhen radar beam intercepts a radar beacon, then a Morse code signal is painted on the PPI.

2.3.18SARTThe instructor can assign a SART (Search And Rescue Transponder) to own ships radar. It isreflected on the radar screen in the form of 12 dots from the center of ownship towards thedirection of the distress vessel / SART signal.

2.3.19Cursor

As shown in Fig-2, the cursor box shows the cursor position with respect to the owship on theradar PPI.


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GLOSSARY OF THE TERMS

ABBREVIATION EXPANSION DEFINITION

ARPA Automatic RadarPlotting Aids.

It is a computer based radar data processor,which automatically and continuously providesthe user with target data.

CPA Closest Point ofApproach

The point nearest to the own ship throughwhich the target ship will cross, if it continueson the same course.

EBL Electronic BearingLine

It is used to measure the bearing of a targetfrom own ship either in True or Relative mode.When selected, the Electronic Bearing Line isdisplayed as a line, originating from ownshipto the outer edge of the Radar display.

GPS Global PositioningSystem

A satellite navigation system intended toprovide highly accurate position and velocityinformation in three dimensions and precisetime and time interval on a global basis,continuously

HL Heading Line The line of course being followed by the ship

RM Motion Mode(Relative)

A relative motion mode (display) shows thechart information, and radar targets, movingrelative to the vessel position fixed on thescreen.

TM Motion Mode (True) A true motion mode (display) shows own-ships position, and other movable data suchas radar targets, moving on the earth-fixedchart background.

OAW Triangle The triangle formed with O being the initialposition of the target ship, A the finalposition and W being the own ships positionin Relative Vector Mode. This gives the CPAand TCPA of the target ship (Course andSpeed) and is helpful in collision avoidance.

PADs Predicted Area of

Danger

It is an area demarcated around the

potential point of collision using the CPA. Ithelps in the calculation of safe courses to beused to avoid the collision

PI Parallel Index Parallel index technique is the art ofmanoeuvring a ship to a desired position oralong a desired track, in such a manner thatthe entire manoeuvre is carried out whilewatching the PPI only

PPI Plan PositionIndicator

It is the display of the Radar/ARPA thatindicates the position and course of thetarget/own ship.


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ABBREVIATION EXPANSION DEFINITION

ROR Rules of the Road A set of rules governing the safe navigationof vessels with an aim to avoid collision. It

includes the usage of light, shape and soundsignals for communication.

SOG Speed Over Ground It is the actual speed made good at anyinstant in time with respect to the groundalong the course being steered

STW Speed ThroughWater

It is the apparent speed indicated by log-type instruments or determined by use oftachometer and speed curve or table, at aparticular point in time, along the course line.

STC Sensitivity TimeControl

Has been explained under section 2.3.6

TCPA Time to CPA The time it will take the target ship to arriveat the Closest Point of Approach with itspresent speed and direction.

VRM Variable RangeMarker

It is used to measure the range of a targetfrom ownship.

Radar-Arpa Operators Manual Controls(1)

Documents

radar screen

radar system

radar application

picture of radar

radar mode2

modethe radar

true course

ready mode andto