RADAR

Question 1

What is RADAR

Answer 1

Radio Detection And Ranging

Question 2

Principle of operation of radar?

Answer 2

Echo ranging principle ( SPEED x TIME) / 2

Question 3

X band characteristics

Answer 3

3cm 9-10 GH/z
High resolution picture for precise Navigation
(Better definition of land)

More accurate bearings

Question 4

S Band characteristics

Answer 4

10cm 3GH/z
Sacrifices High resolution for relative freedom from Sea and Rain clutter

Improved range

Question 5

What determines the Pulse length

Answer 5

Determined by range scale in use

Question 6

What determines the Pulse Repetition frequency?

Answer 6

Determined by range scale in use.

Short ranges have a high PFR
Long ranges have a low PFR

Can be fine tuned once at desired range, for need of function.

Question 7

What is the Sea clutter function?

Answer 7

Suppresses the gain, applies this to the area near to the ship. Never extends the whole range

Only to be used if sea conditions require it

Question 8

Equations for range of targets on radar

Answer 8

Range = speed x Time/ 2
Range = speed x Time / ( 2 x 1852 )

Question 9

What two inputs should you check when setting up a stabalised radar?

Answer 9

Heading input (Gyro)
Speed input (STW/SOG)

Question 10

How do we set up Brilliance, Gain, Tuning

Answer 10

Brilliance: Increase to a level which allows the OOW to see the display clearly

Gain: adjust so that a lightly speckled background of clutter can be seen

Tuning: adjust for best response from a small target on the edge of the display

Question 11

What is Rain Clutter on a radar and how dows it work

Answer 11

Cuts through range clutter and interference.

Does this by trying to cut off the trailing edge so that just the leading edge is seen.

Question 12

5 features in determining a good radar conspicuous object

Answer 12

1.Material
2. Aspect
3. Size (height and breadth above horizon)
4. Texture of surface
5. Shape

Question 13

Radar echo errors:

Answer 13

False Echo
Indirect Echo
Side Lobe Error
Multiple Echoes
RADAR interference
Target Loss and Target Swap

Question 14

SART

Answer 14

X band 3 cm radar, Used for detection of casualties in SAR situations

Question 15

Factors to consider when setting CPA/ TCPA alarm on radar

Answer 15

Sate of visibility
Traffic Density
Manoeuvrability of vessel
Proximity of navigational hazards
Masters standing orders

Question 16

In order, 6 pieces of information ARPA gives about a target

Answer 16

1. present range
2. present bearing
3. Predicted CPA
4. predicted TCPA
5. Calculated True course
6. Calculated True speed

Question 17

How many targets can an OOW expect to have selected for ARPA?

Answer 17

20-40

Question 18

How to setup a RADAR

Answer 18

1. Check for Obstructions
2. Turn on Radar (allow magnetron to warm up)
3. Press transmit (turn controls to 0)
4. Brilliance
   Range
   Gain
   Tune
   Clutter ( rain and sea )

Question 19

How often should we run the performance monitor function

Answer 19

Once per watch, or when unsure as to the reliability of the RADAR
Record in log

Question 20

What are blind and shadow sectors?

Answer 20

Blind and shadow sectors are fixed areas that the radar’s view is partially (shadow) or totally obstructed (blind).

Card for sectors should be in Bridge

Question 21

How can we find our Shadow/Blind Sectors?

Answer 21

In the instillation Manual, in the Yellow booklet provided

By turning up the gain and looking for these sectors when operating the radar.

Question 22

How do we Tune our radar?

Answer 22

Adjust until we have the best visual picture
NOT AUTO for the sake of the exam

Question 23

How do you know if it is correctly tuned?
In coastal nav?
At sea?
At sea with no swell?

Answer 23

Tune to a conspicuous object/point of contact

At sea, tune to the sea clutter

If no swell, turn vessel to create wake and tune to the vessels own wake

Question 24

RADAR pre departure checks:

Answer 24

Obstruction of RADAR

BRGTC

Heading marker aligned to fore and aft centreline of the vessel

EBL against gyro bearing of an object
PM function to check range rings

Question 25

Setting up X band Radar for SART detection:

Answer 25

Range: 6-12nm
Tuning: De-tune
Gain: Normal gain for long range detection
Video processing, Rain: Used as normal
Video processing, Sea: Reduced to Minimum

Question 26

ARPA alarms

Answer 26

Target has breached user-set CPA and TCPA

Tracked target is lost

An input failure (gyro, speed etc)

A target enters a guard zone (one that is not already tracked)

Picture freeze