RADAR FUNDAMENTALS

1. Compiled by 3/O Moises T. Teñosa
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2. COURSE OBJECTIVES CONTENTS SUMMARY

4. • 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.

5. 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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6. RADAR

7. How
does
RADAR
work?

9. Components of a radar system
INDICATOR-
OR PPI
TRANSMITTERMODULATOR
ANTENNA
CREATES HIGH ENERGY
RADIO FREQUENCY
WAVES
TURNS RADIO
FREQUENCIES
ON AND OFF
RECEIVER
TRANSMIT
RECEIVE
ROTATING
ANTENNA

10. CRT

11. LCD

12. Color
Black Box

13. Pulse Length
Receiver Sensitivity
Frequency
Power Output
Horizontal Beam Width

14. THETHE
PPLANLAN
PPOSITIONOSITION
IINDICATORNDICATOR
OROR PPIPPI
wide beam widthwide beam width
RADARRADARBeam width is moreBeam width is more
important than powerimportant than power

15. THETHE
PPLANLAN
PPOSITIONOSITION
IINDICATORNDICATOR
OROR PPIPPI
RADARRADARBeam width is moreBeam width is more
important than powerimportant than power
narrow beam widthnarrow beam width

16. large antenna
narrow beam width

17. small antenna
wide beam width

18. Maximum Radar Range
D = 1.22 H
D = 1.22 X 5.48 = 6.68 nm
where radar is 30 feet above the water

20. It can display the location
of certain fixed and moving
objects in relation to your vessel
Radar --
is not electronic Navigation
Radar cannot tell you where you are
Radar -- is electronic plotting

21. animation

22. but
RADAR generates
a
relative motion
picture

23. Geographic Plot shown on Maneuvering Board

24. Radar Plot
2300
2200Relative Motion
Radar Plot
Geographic Plot shown on Maneuvering Board FormRadar Plot

25. animation

26. animation

27. The
Plan
Position
Indicator
Or PPI
A target whose range
is decreasing and
relative bearing is
not changing is on a
collision course

28. Make a RADICAL
Course Change
in order for it
TO BE OBVIOUS
on Radar

29. CPA
Closest Point of Approach
CPA

30. RADAR PLOTTING AND
RELATIVE MOTION
VESSEL IS STEAMING ON
A COURSE
OF
280 T AT 9 KNOTS
THE PPI SHOWS TARGETS
at 1305 323 R 9.0 nm
at 1313 324 R 6.5 nm
at 1320 327 R 4.4 nm
at 1325 331 R 3.0 nm

31. RADAR PLOTTING AND
RELATIVE MOTION
HOW CLOSE WILL
THIS TARGET COME
TO OUR VESSEL,
AND AT WHAT
TIME WILL IT
APPROACH
CLOSEST TO OUR
VESSEL

32. RADAR PLOTTING AND
RELATIVE MOTION
13051305
13131313
13201320
13251325
CONVERT RELATIVE
BEARINGS TO
TRUE BEARINGS
322 + 280 = 242
324 + 280 = 244
327 + 280 = 247
334 + 280 = 251
PLOT ON
MANEUVERING BOARD
LABEL EACH
WITH TIME OBSERVED

33. RADAR PLOTTING AND
RELATIVE MOTION
1305
1313
1320
1325
DIRECTION
OF RELATIVE
MOTION
=>
DRAW A LINE
THROUGH
ALL 4 POINTS

34. RADAR PLOTTING AND
RELATIVE MOTION
1305
1313
1320
1325
DIRECTION
OF RELATIVE
MOTION
=>
D = 6.1
RELATIVE SPEED
OF TARGET
T = 1325 - 1305
T = 0020
S = 60 X D
T
S = 60 X 6.1
20
S = 18.3 kts
RELATIVE SPEED =18.3 kts

35. RADAR PLOTTING AND
RELATIVE MOTION
1305
1313
1320
1325
DIRECTION
OF RELATIVE
MOTION
=>
RELATIVE COURSE = 058
RELATIVE
COURSE = 058

36. RADAR PLOTTING AND
RELATIVE MOTION
1305
1313
1320
1325
DIRECTION
OF RELATIVE
MOTION
=>
YOUR SHIP IS
AT THE CENTER
CLOSEST POINT
OF APPROACH
IS
FROM THE CENTER
OF
MANEUVERING BOARD
TO
THE LINE
OF
RELATIVE MOTION
(AT RIGHT ANGLES)
058 - 90 = 328

37. RADAR PILOTING AND
RELATIVE MOTION
1305
1313
1320
1325
DIRECTION
OF RELATIVE
MOTION
=>
MEASURE CPA
DISTANCE
CPA
DISTANCE
IS
0.7 nm
at 1328

38. RADAR PLOTTING AND
RELATIVE MOTION
1305
1313
1320
1325
DIRECTION
OF RELATIVE
MOTION
=>
T = 60 D
S
T = 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 POINT
TO CPA IS 9 nm.

39. RADAR PLOTTING AND
RELATIVE MOTION
13051305
13131313
13201320
13251325
DIRECTION
OF RELATIVE
MOTION
=>
DIRECTION
OF RELATIVE
MOTION
=>
THE RADAR TARGET
WILL APPROACH
CLOSEST
TO THE SHIP
AT 1335
THE CLOSEST
IT WILL COME
WILL BE 0.7 nm

40. RADAR PLOTTING AND
RELATIVE MOTION
WHAT IS
THE SPEED
AND
DIRECTION
OF
THE
TARGET?

41. RADAR PLOTTING AND
RELATIVE MOTION
C280
S9
THIS IS NOW
A VELOCITY
PLOT ON
THE MANEUVERING
BOARD
PLOT YOUR
VESSEL’S
VELOCITY VECTOR
OWN CRS
AND SPD

42. RADAR PLOTTING AND
RELATIVE MOTION
C280
S9
PLOT
RELATIVE VELOCITY
VECTOR OF TARGET
058
at 18.3 kts
REL CRS 058
REL VEL 18.3

43. RADAR PLOTTING AND
RELATIVE MOTION
C280
S9
DRAW VECTOR
FROM
CENTER
TO
HEAD OF RELATIVE
VELOCITY VECTOR
OF
TARGET

44. RADAR PILOTING AND
RELATIVE MOTION
C280
S9
THIS IS
THE TARGET’S
TRUE COURSE
030
AND ITS
TRUE SPEED
13 kts

45. WHAT REALLY HAPPENED
IN REAL TIME ON THE WATER

46. WHAT REALLY
HAPPENED
OWN SHIP
POSITION
AT 1305 HOURS
TARGET IS 242 T
AT 9 MILES
Target Position
at 1305
242 T 9 nm
Own SHIP Position
at 1305

47. WHAT REALLY
HAPPENED
OUR SHIP
POSITION
AT 1313
TARGET IS 244 T
AT 6.5 nm
Target Position
at 1313
Advance own SHIP from
the 1305 position to
the 1313 position
1305
1313 - 1305 = 8
60 D = S x T
D = S x T / 60
D = 9 x 8 / 60
D = 1.2 nm
244 T 6.5 nm
242 T 9 nm
1313

48. 1305
WHAT REALLY
HAPPENED
Advance own ship from
the 1305 position to
the 1320 position
1320
OUR SHIP
POSITION
AT 1320
TARGET IS 247 T
AT 4.4 nm
1320 - 1305 = 15
60 D = S x T
D = S x T / 60
D = 9 x 15 / 60
D = 2.25 nm
247 T 4.4 nm
244 T 6 nm
242 T 9 nm

49. WHAT REALLY
HAPPENED
Advance own ship from
the 1305 position to
the 1325 position
1325
OUR SHIP
POSITION
AT 1325
TARGET IS 251 T
AT 3 nm
1325 - 1305 = 20
60 D = S x T
D = S x T / 60
D = 9 x 20 / 60
D = 3 nm
244 T 6 nm
242 T 9 nm
247 T 4.4 nm
251 T 3 nm
1305

50. WHAT REALLY
HAPPENED
TARGET SHIP
DIRECTION IS
030 TRUE
1325
OWN SHIP
WILL THE
TWO SHIPS
COLLIDE?
TARGET
SHIPSHIP
242 T 9 nm
244 T 6 nm
247 T 4.4 nm
251 T 3 nm
1305

51. WHAT REALLY
HAPPENED
CALCULATED
CLOSEST POINT
OF APPROACH
OCCURS AT
1335
TARGET
SHIPSHIP
242 T 9 nm
251 T 3 nm
OWN SHIPT
1325
1305
TARGET SHIP
COURSE
DIRECTION IS
030 TRUE
WILL THE
TWO SHIPS
COLLIDE?

52. WHAT REALLY
HAPPENED
TARGET
SHIPSHIP
1305
1335
OWN SHIP
242 T 9 nm
251 T 3 nm
WILL THE
TWO SHIPS
COLLIDE?
AT 1335
OWN SHIP POSITION
IS:
1335 - 1305 = 30
D = S X T / 60
D = 9 X 30 / 60
D = 4.5

53. WHAT REALLY
HAPPENED
242 T 9 nm
251 T 3 nm
1335
TARGET
SHIPSHIP
OWN
SHIPSHIP
1335
1305
WILL THE
TWO SHIPS
COLLIDE?
AT 1335
TARGET
SHIP POSITION
IS:
1335 - 1305 = 30
D = S X T / 60
D = 13 X 30 / 60
D = 4.5
ADVANCE THE TARGET SHIP
FROM 1305 TO 1335 POSITION

54. .7 MILES.7 MILES
WHAT REALLY
HAPPENED
WILL
THE
TWO
SHIPS
COLLIDE?
OWN
SHIPSHIP
1335
1305
TARGET
SHIPSHIP
MEASURE THE
DISTANCE BETWEEN THE
BLUE AND ORANGE
DOTS
1335
0.7 MILES0.7 MILES
NO!

55. RADAR PLOTTING AND
RELATIVE MOTION
1305
328
OWN
SHIPSHIP
TARGET
SHIPSHIP
0.7 MILES 0.7 MILES
328 DEGREES TRUE
TO
THE
CLOSEST POINT
OF
APPROACH

57. 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

58. Range

59. Bearing

60. Entering Harbor

61. RACON

62. 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.

63. 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.

64. Re-Usable Maneuvering Board

67. RETURN

68. 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.

69. • 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.

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

72. • 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.

74. RETURN
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