Cd.49 Radar Observation & Plotting

FUNDAMENTAL THEORY

1. What is the radar sweep?

• transmission of one pulse only

2. Which radar condition can be expected when stationary warm air is located on top of cold sea?

• radar black-out

3. What is the main function of the antenna?

• to transmit and receive radar signals

4. What is the effect of Sub-reflection?

• distance to radar horizon is reduced

5. What is the radar scan?

• transmission of pulse during one 360º rotation of the antenna

6. What is the meaning of “radar range resolution”?

• the radar ability to separate targets in range

7. What is the function of the Magnetron?

• generate radar pulses

8. What is the meaning of “radar bearing resolution”?

• the radar ability to separate targets in bearing

9. Does the number of pulses transmitted per second affect the radar maximum range?

• yes

10. We have normal transmission of radar waves when the radar horizon is?

• 10% longer away than the optical horizon

11. How does radar antenna height influence on sea clutter?

• High antenna height, more sea clutter

12. The reflection of radar pulses is similar to that of?

• light

13. What is the relation between scanner width (size) and horizontal beam with?

• large scanner with, narrow horizontal beam width

14. What is the main function of the receiver?

• amplify the incoming signals

15. What are two main purposes of marine radar?

• traffic surveillance and navigation

16. The horizontal extension of the target affects the echo pulse?

• little

17. Does the ships trim affect radar minimum range?

• yes

SETTING UP RADAR DISPLAY

1. What is the purpose of the Drift controls?

• used to ground stabilize True Motion display

2. What is the purpose of the VRM control?

• to measure distance accurately

3. Marine radar bearing accuracy is generally?

• not so good

4. Which course should be fed in to a stabilized radar picture?

• true course

5. How to reduce beam width distortion?

• reduce Gain

6. What is the purpose of the HL-suppress button?

• to switch off the HL temporarily

7. What is the purpose of the Brilliance control?

• Adjust signal intensity on the display

8. Marine radar range accuracy is generally?

- High

MARINE RADAR PERFORMANCE SPECIFICATION

1. The radar must be able to operate in relative wind speeds up to?

- 100 knots

2. What is the required accuracy of the heading marker?

- +/- 1 deg

3. IMO resolution 477 applies to all ships built after?

- 1984

4. What is the minimum radar display diameter for ships of 10000 tons and upwards?

- 16 inch

5. What is the minimum number if range scales required?

- 5

6. What is the minimum display diameter required on ships bigger than 1600 tons but less than 10000 tons?

- 250mm

7. What is the maximum radar “warm-up” time?

- 4 min

8. It is a requirement to have the HM-suppress button spring loaded?

- Yes, it is a IMO requirement.

PLOTTING

1. When plotting north up, you plot?

- Bearings

2. What is the effect of gyro error?

- All bearings will be wrong.

3. What is the main advantage of true plotting?

- Easy to understand

4. What is the main purpose of plotting?

- Obtain information about weather danger of collision exists, CPA, TCPA, targets course and speed

5. What is the main purpose of Seaspeak?

- Reduce maritime communication problems.

6. What is the effect of error in time between two plots?

- Error in CPA, TCPA and target course.

7. What is the effect of using incorrect bearings in plotting?

- CPA, TCPA, Course and Speed are effected.

8. What is the usual method of deciding whether collision danger exist or not?

- By taking several bearings of the target.

THE USE OF RADAR IN NAVIGATION

1. Use of radar to assist in navigation can be divided in?

- 3 groups

2. How is an uncoded racon displayed on the PPI?

- As a line

3. What is the main purpose of the parallel index line?

- Assist the navigator in obtaining a decided CPA to a selected point.

4. What is the purpose of the radar reflector?

- Making small objects better visible

5. What is a coded racon?

- A racon which display a morse code on the radar screen.

6. Radar navigation have X important motion components?

- 3

7. What type of radar can active a racon?

- X-band radar

8. Does the racon show up on a C-band radar?

- No

RADAR AND COLREG

1. Does the COLREG give any preference to ships equipped with radar?

- No

2. COLREG no 35 specify?

- Sound signals during reduced visibility.

3. What is the main content of COLREG no 5?

- Proper look out.

4. COLREG no 10 apply to?

- Vessels sailing in separation schemes

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