RADAR Flashcards
Pulse Length
Determined by the design of the modulator circuit.
Short/Medium/Long depending on range scale in use.
Carrier Frequency
Transmission radio frequency
X band
+ state preferred adv.
3cm 9-10 GHz
Better Resolution, preferred for navigation
S Band
+ state preferred adv.
10 cm 3 GHz
Better in rain, longer range
Sea Clutter (or STC; Sensitivity Time Constant)
+Correct setting?
Reduces reflections from waves near ship by reducing sensitivity of receiver from centre out.
Proper Setting: Clutter reduced, echoes distinguishable.
Precipitation Clutter
Reduces reflected echoes from rain, hail or snow to clear display.
Via video processing it doesn’t display leading edge returns.
Detection Characteristics of Radar Targets
MASTS
Material
Aspect
Size
Texture
Shape
RADAR meaning
RAdio Detection And Ranging
Setting up a Radar
(3 points)
- Check scanner is clear
- Turn ON
- BIG RANDY GIRLS TAKE COCK
Brilliance
Range
Gain - light background speckle (70%)
Tuning - need to be receiving something
Clutter
Pre departure radar checks
(+ every 4 hrs WATCH min)
(list 4 steps)
then done < 4 hrs of radar watch.
(MGN 379)
- On + Running
- Performance Monitor
- VRM against range rings
- EBL using charted object with heading marker against compass
Good Radar Practice
(5 points)
- Quality of radar performance checked regularly
- Misalignment of heading marker can lead to misinterpreting collision situations.
- Small vessels, ice and other floating objects may not be detected by radar
- Echoes may be obscured by sea or rain clutter
- Masts or other structural features may cause shadow or blind sectors on display.
other:
- Video processing techniques used with care
Performance Monitor
Provides a check of the performance of transmitter.
Plume length - Strength of echo received
Radar Displays
H-Up : Un-stabilised- does not utilise heading input. Reverted to after heading input failure.
C-Up : Stabilised - heading input from a Gyro or transmitting heading device (THD)
N-Up : Stabilised - heading input from a Gyro or transmitting heading device (THD)
Ground stabilisation
(6)
- Coastal Navigation
- COG + SOG input
- Speed and Heading from GNSS
- Set and Drift visually shown
- difficulty determining true aspect
- fixed target will appear stationary
Sea Stabilisation
(6)
- Collision Avoidance
- CTW + STW input
- Speed and heading from Gyro and Log
- Doesn’t account for set and drift
- true aspect easily determined
- fixed target will have a vector direction rec. to set and speed indicates rate of drift
