copy of radionavigation radar

Compiled by 3/O Moises T. Teñosa

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COURSE OBJECTIVES CONTENTS SUMMARY

• On completion of the subject, the students should be able to plot positions by means of radar, making them capable of navigating safely in all parts of the world. They will have specific knowledge the operating principles, limitations, sources of error and methods of correction to radar to obtain accurate position fixing. They will have enough skills in radar plotting for collision avoidance.

CONTENTS

• 1. Fundamental of Radar

• 2. Radar Components and System

• 3. Radar Motion Display

• 4. Radar Controls

• 5. Introduction to Radar Plotting and Tracking Problems

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How

does

RADAR

work?

Components of a radar system

INDICATOR-OR PPI

TRANSMITTERMODULATOR

ANTENNA

CREATES HIGH ENERGYRADIO FREQUENCY

WAVES

TURNS RADIOFREQUENCIES

ON AND OFF

RECEIVER

TRANSMIT

RECEIVE

ROTATINGANTENNA

ColorBlack Box

Pulse Length

Receiver Sensitivity

Frequency

Power Output

Horizontal Beam Width

THETHE

PPLANLAN

PPOSITIONOSITION

IINDICATORNDICATOROROR PPI PPI

wide beam widthwide beam width

RADARRADARBeam width is moreBeam width is more important than powerimportant than power

THETHE

PPLANLAN

PPOSITIONOSITION

IINDICATORNDICATOROROR PPI PPI

RADARRADARBeam width is moreBeam width is more important than powerimportant than power

narrow beam widthnarrow beam width

large antenna

narrow beam width

small antennawide beam width

Maximum Radar Range

D = 1.22 H

D = 1.22 X 5.48 = 6.68 nm

where radar is 30 feet above the water

It can display the locationof certain fixed and moving objects in relation to your vessel

Radar --is not electronic NavigationRadar cannot tell you where you

are

Radar -- is electronic plotting

anim

atio

n

but

RADAR generates

a

relative motion

picture

Geographic Plot shown on Maneuvering Board

Radar Plot

23002200Relative Motion

Radar Plot

Geographic Plot shown on Maneuvering Board FormRadar Plot

anim

atio

n

ThePlan

PositionIndicator

Or PPI

A target whose rangeis decreasing andrelative bearing isnot changing is on acollision course

Make a RADICAL

Course Change

in order for it

TO BE OBVIOUS

on Radar

CPA

Closest Point of Approach

CPA

RADAR PLOTTING ANDRELATIVE MOTION

VESSEL IS STEAMING ONA COURSE

OF280 T AT 9 KNOTS

THE PPI SHOWS TARGETS

at 1305 323 R 9.0 nmat 1313 324 R 6.5 nmat 1320 327 R 4.4 nmat 1325 331 R 3.0 nm


HOW CLOSE WILL THIS TARGET COME

TO OUR VESSEL, AND AT WHATTIME WILL IT APPROACH

CLOSEST TO OUR VESSEL


1305130513131313

1320132013251325

CONVERT RELATIVEBEARINGS TO

TRUE BEARINGS

322 + 280 = 242324 + 280 = 244327 + 280 = 247334 + 280 = 251

PLOT ON MANEUVERING BOARD

LABEL EACH WITH TIME OBSERVED


13051313

13201325

DIRECTION O

F RELATIVE MOTIO

N =>

DRAW A LINE THROUGH

ALL 4 POINTS


13051313

13201325

DIRECTION O

F RELATIVE MOTIO

N =>

D = 6.1

RELATIVE SPEED OF TARGETT = 1325 - 1305

T = 0020

S = 60 X D T

S = 60 X 6.1 20

S = 18.3 kts

RELATIVE SPEED =18.3 kts


13051313

13201325

DIRECTION O

F RELATIVE MOTIO

N =>

RELATIVE COURSE = 058

RELATIVE COURSE = 058


13051313

13201325

DIRECTION O

F RELATIVE MOTIO

N =>

YOUR SHIP ISAT THE CENTER

CLOSEST POINT OF APPROACH

IS FROM THE CENTER

OFMANEUVERING BOARD

TO THE LINE

OF RELATIVE MOTION

(AT RIGHT ANGLES)

058 - 90 = 328

RADAR PILOTING ANDRELATIVE MOTION

13051313

13201325

DIRECTION O

F RELATIVE MOTIO

N =>MEASURE CPA

DISTANCE

CPA DISTANCE

IS

0.7 nm

at 1328


13051313

13201325

DIRECTION O

F RELATIVE MOTIO

N =>

T = 60 D ST = 60 X 9 = 30 MIN 18.3

MEASURE DISTANCE FROM

1305 POINT TO CPA POINT

COMPUTE TIME

TO TRAVERSE

FROM

1305 PT TO CPA

ADD TIME TO 1305

1305 + 0030 = 1335

CPA OCCURS AT 1335

COMPUTE TIME TO CPA

DISTANCE FROM 1305 POINTTO CPA IS 9 nm.


1305130513131313

1320132013251325

DIRECTION O

F RELATIVE MOTIO

N =>

DIRECTION O

F RELATIVE MOTIO

N =>

THE RADAR TARGET

WILL APPROACH

CLOSEST

TO THE SHIP AT 1335

THE CLOSEST IT WILL COME

WILL BE 0.7 nm


WHAT IS THE SPEED

AND DIRECTION

OF THE

TARGET?


C280S9

THIS IS NOW A VELOCITY

PLOT ON THE MANEUVERING

BOARD

PLOT YOUR VESSEL’S

VELOCITY VECTOR

OWN CRSAND SPD


C280S9

PLOT

RELATIVE VELOCITY

VECTOR OF TARGET

058

at 18.3 kts

REL CRS 058REL VEL 18.3


C280S9

DRAW VECTOR

FROM

CENTER

TO

HEAD OF RELATIVE

VELOCITY VECTOR

OF

TARGET

RADAR PILOTING ANDRELATIVE MOTION

C280S9

THIS IS

THE TARGET’S

TRUE COURSE

030

AND ITS

TRUE SPEED

13 kts

WHAT REALLY HAPPENED IN REAL TIME ON THE WATER

WHAT REALLYHAPPENED

OWN SHIP

POSITION

AT 1305 HOURS

TARGET IS 242 T

AT 9 MILES

Target Positionat 1305

242 T 9 nm

Own SHIP Positionat 1305

WHAT REALLYHAPPENED

OUR SHIP

POSITION

AT 1313

TARGET IS 244 T

AT 6.5 nm

Target Positionat 1313

Advance own SHIP fromthe 1305 position to

the 1313 position

1305

1313 - 1305 = 860 D = S x T

D = S x T / 60D = 9 x 8 / 60D = 1.2 nm

244 T 6.5 nm

242 T 9 nm

1313

1305

WHAT REALLYHAPPENED

Advance own ship fromthe 1305 position to

the 1320 position

1320

OUR SHIP

POSITION

AT 1320

TARGET IS 247 T

AT 4.4 nm

1320 - 1305 = 1560 D = S x T

D = S x T / 60D = 9 x 15 / 60D = 2.25 nm

247 T 4.4 nm

244 T 6 nm

242 T 9 nm

WHAT REALLYHAPPENED

Advance own ship fromthe 1305 position to

the 1325 position

1325

OUR SHIP

POSITION

AT 1325

TARGET IS 251 T

AT 3 nm

1325 - 1305 = 2060 D = S x T

D = S x T / 60D = 9 x 20 / 60

D = 3 nm

244 T 6 nm

242 T 9 nm

247 T 4.4 nm251 T 3 nm

1305

WHAT REALLYHAPPENED

TARGET SHIPDIRECTION IS

030 TRUE

1325OWN SHIP

WILL THE TWO SHIPSCOLLIDE?

TARGETSHIPSHIP

242 T 9 nm

244 T 6 nm

247 T 4.4 nm

251 T 3 nm1305

WHAT REALLYHAPPENED

CALCULATEDCLOSEST POINTOF APPROACH

OCCURS AT1335

TARGETSHIPSHIP

242 T 9 nm

251 T 3 nm

OWN SHIPT1325

1305TARGET SHIP

COURSEDIRECTION IS

030 TRUE


WHAT REALLYHAPPENED

TARGETSHIPSHIP

1305

1335OWN SHIP

242 T 9 nm

251 T 3 nm


AT 1335

OWN SHIP POSITIONIS:

1335 - 1305 = 30

D = S X T / 60

D = 9 X 30 / 60

D = 4.5

WHAT REALLYHAPPENED

242 T 9 nm

251 T 3 nm

1335

TARGETSHIPSHIP

OWN SHIPSHIP

1335

1305


AT 1335

TARGETSHIP POSITION

IS:

1335 - 1305 = 30

D = S X T / 60

D = 13 X 30 / 60

D = 4.5

ADVANCE THE TARGET SHIPFROM 1305 TO 1335 POSITION

.7 MILES.7 MILES

WHAT REALLYHAPPENED

WILL THE TWO

SHIPSCOLLIDE?

OWNSHIPSHIP

1335

1305

TARGETSHIPSHIP

MEASURE THEDISTANCE BETWEEN THE

BLUE AND ORANGEDOTS

1335

0.7 MILES0.7 MILES

NO!


1305

328

OWN SHIPSHIP

TARGETSHIPSHIP

0.7 MILES 0.7 MILES

328 DEGREES TRUE TO

THE CLOSEST POINT

OFAPPROACH

Order of preference for accuracy

To determine position•Visual observation of object’s relative bearing and distance Determined by radar•Radar range to two objects•Radar range and radar relative bearing on same object•Radar relative bearings to two Different objects

Bearing

Entering Harbor

Steering and Sailing Rules

Rule 7

Risk of Collision(a) Every vessel shall use all available means appropriate to the prevailing circumstances and conditions to determine if risk of collision exists. If there is any doubt such risk shall be deemed to exist.

(b) Proper use shall be made of radar equipment if fitted and operational, including long-range scanning to obtain early warning of risk of collision and radar plotting or equivalent systematic observation of detected signals.

(c) Assumptions shall not be made on the basis of scanty information, especially scanty radar information.

Steering and Sailing Rules

Rule 7

Risk of Collision (continued)(d) In determining if risk of collision exists the following considerations shall be among those taken into account.

(I) such risk shall be deemed to exist if the compass bearing of an approaching vessel does not appreciably change;

(ii) such risk may sometimes exist even when an appreciable bearing change is evident, particularly when approaching a very large vessel or a tow or when approaching a vessel at close range.

Re-Usable Maneuvering Board

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The following paragraphs summarize the

important points of this chapter.• RADAR is an electronic system that uses

reflected electromagnetic energy to detect the presence and position of objects invisible to the eye.

• TARGET POSITION is defined in reference to true north, the horizontal plane, and the vertical plane.

• TRUE BEARING is the angle between true north and the line of sight to the target, measured in a clockwise direction in the horizontal plane.

• ELEVATION ANGLE is the angle between the horizontal plane and the line of sight, measured in the vertical plane.

• RANGE is the distance from the radar site to the target measured along the line of sight. The concepts are illustrated in the figure.

• BEARING RESOLUTION is the ability of a radar to separate targets at the same range but different bearings. The degree of bearing resolution is dependent on beam width and range. The accuracy of radar is largely dependent on resolution.

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copy of radionavigation radar

Business

radar plotting

direction of relative

radar target

relative motion vessel

radar motion display

line of relative motion

relative motion picture

relative course