RADAR Flashcards
What does RADAR stand for?
RAdio Detection And Ranging.
What are the carriage requirements of the Radar?
Under SOLAS Ch.5 Reg.19:
- Cargo Ships 300gt and above, and passenger ships regardless of size must carry an X-Band RADAR.
- Vessels over 3,000gt are required to carry an additional X-Band RADAR or an S-Band RADAR, must work independently.
Which RADAR is able to detect SART?
X-Band
What wavelength and frequency does both the X-Band and S-Band RADARS transmit?
- X-Band: 3cm and 9Ghz
- S-Band: 10cm and 3Ghz
Which Radar is less likely to be affected by Rain and Heavy Weather conditions?
S-Band
Which Radar is less likely to swap targets that pass eachother?
X-Band
What are the performance standards for the RADAR, state the MSC resolution.
- Frequency Bands
- Range & Bearing Accuracy
- Detection Range
- Range Discrimination
- Bearing Discrimination
- Roll & Pitch
- Range Scales
- Should be fully operational within a cold start within? And from Standby mode within?
MSC resolution 192(79)
- As per the International Telecommunications Union (ITU)
- Range 1% of scale used or 30m, whichever is greater. Bearing within 1 degree.
- Detection Laid out depending on object
- In a scale of 1.5nm or less, it should display two objects on the same bearing and 40 meters apart on two objects
- In a scale of 1.5nm or less, it should display two objects on the same range with 2.5 degrees apart as two objects
- Can detect while up to +/- 10 of roll
- Mandatory Range scales 0.25, 0.5, 0.75, 1.5, 3, 6, 12, 24nm.
- Cold start: 4 minutes, standby: 15 seconds
What are some factors to determining to appropriate Radar range to use?
- Traffic Density
- Our Speed
- Weather Conditions
- Navigational Hazards
- Frequency of Observation
What are the different orientations of Radar?
- Head Up: Heading marker vertically displayed, Radar image matches window.
- North Up: North is Top of Screen, matches orientation of chart.
- Course Up: Vessel always pointing towards top of screen
If the gyro-compass input fails, which orientation will the radar automatically switch to?
Head Up
What is the most common radar orientation used by seafarers)
North Up
What two types of motion is used in a Radar?
- Relative Motion
- True Motion
Describe how relative motion looks on a Radar.
Our position is fixed on the screen while objects around us move in relation to us. Stationary object are shown as moving.
Describe how true motion looks on a Radar.
Our vessel moves across the screen and has a vector, stationary objects don’t move.
What two stabilization methods are there on a Radar? And how can you describe them?
- Sea Stabilized: Our motion through the water
- Ground Stabilized: Our motion over the ground
How would a fixed target look in sea/ground stabilization mode?
- Sea: Will have a vector direction reciprocal to the set and drift
- Ground: Will be stationary and have no trail
Speed input for sea/ground stabilization mode on a Radar?
- Sea: Speed Log - STW
- Ground: GNSS - COG & SOG
According to the MCA, which stabilization mode on a Radar should I use for collision-avoidance and which should I use use for coastal navigation? And why?
- Collision avoidance: Sea. Easier to determine other ship’s true aspect
- Coastal Navigation: Ground, land and fixed object will have no trail and appear stationary.
It is easier to determine the true aspect of other vessels on which stabilization mode on a Radar?
Sea Stabilization
How often should the performance test be done on the Radar? What feedback values are we expecting?
On start-up and Once per watch, feedback with reference to manufacturer’s instructions.
What is the order in which you set-up a Radar?
B - G - T - Rain then Sea
B: Brilliance
G: Gain
T: Tune
What is the Brilliance adjusting on the Radar?
The brightness of the screen.
How would you set up the Gain on a Radar?
Adjust it until there is light speckles on the screen.
What is the purpose of the rain/sea clutter on the Radar?
Rain: Thins out the rain enabling us to detect targets that would’ve been hidden under the rain
Sea: Reduces the returning pulses from sea waves around the vicinity of the vessel.
Which Radar orientation is not stabilized?
Head Up
What are the limitations of the Radar?
- Antenna Height
- Blind Sectors
- Clutter
What are the errors of the Radar?
- Side-Lobe Error
Radiation leaks out of the side of the scanner - Multiple Echos
If the wave is reflected multiple times - Second Trace Echo
When the pulse travels and returns after the radar has transmitted another pulse. - Indirect Echo
A pulse is reflected off a part of the ship before returning - Input Errors
The integrated equipment feeding the Radar with information.
How much rain and sea clutter should be applied to the Radar?
The minimum necessary to achieve a usable image. Avoid “Clean” Radar screens.
What is likely to occur on the vessel’s blond sector?
Targets will not be detected and acquired targets are likely to be lost.
A position fix must be comprised of how many lines?
Three lines.
Which is the most accurate manual position fixing method?
Range and Range, it eliminates the many errors of taking compass bearings.
Which MGN gives guidance on the use of electronic navigation aids?
MGN 379
Battery life of SART in standby mode, and how long does it transmit for once interrogated by a Radar?
96 Hours, transmits for 8 hours once interrogated by Radar.
How does a SART appear on a Radar w as t different ranges?
- At 12nm, 12 blips towards the SART
- At 6nm, the blips grow into arcs
- At 1nm, the arcs will become full circles around your vessel
How does a Radio Beacon (RACON) appear on a Radar Screen?
A series of dots and dashes to resemble a Morse code character.
Where is the SART located in relation to the twelve dots?
The first dot.
