ROU Written Exam - OOD 2023 Questions and Answers
with complete solution
What does RADAR stand for?
Radio Detection and Ranging
What are the steps to Situational Awareness?
Appraise, plan, execute, monitor, revise
Name 3 purposes of RADAR
Navigation, collision avoidance, situational awareness
Radar helps reduce uncertainty in the collision avoidance process. What other
information may be used in the collision avoidance process?
VHF radio + visual contact
What control would you use to reduce the clutter created by rain squalls?
FTC (Fast Time Constant)
What control would you use to reduce the clutter created by sea return?
STC (Sensitivity Time Control)
If your RADAR is not picking up known targets, what control should you check?
Assume no mechanical problems.
Suppression
What could be the impact of improperly tuning your RADAR?
Loss of targets, no detection
On what two frequency bands do RADAR waves transmit?
-3cm / X Band / 9500 MHz (activates RACON + SART)
-10 cm / S Band / 3000 MHz
What is the impact of own ship yaw on situation assessment on an unstabilized
radar display?
Target smear
In general, is a radar range more accurate than radar bearing?
Yes - RADAR
Which edge of the radar range ring is used to measure range (inner or outer edge
measured from the center)?
Outer
What are some of the factors that control the maximum distance a target can be
detected?
-Pulse width (power of transmitter)
-Height of Antenna
-Atmospheric conditions
-Characteristics of Target (size, shape, texture, material)
The radar's ability to discriminate between targets positioned one behind the
other is primarily controlled by what factor?
Pulse width - range resolution
The radar's ability to generate an accurate bearing resolution is primarily
controlled by what factor?
Horizontal Beam width - bearing resolution
About how many degrees wide is the typical horizontal beam width on a radar?
, 0.7 - 2.0 degrees / IMO 2 degrees
Name 4 factors which control the size of the target painted (spot size)?
-Horizontal beam width
-Pulse length
-Pulse repetition rate
-Target responsiveness
Which radar band gives the best resolution at close range?
3 cm / X Band / 9500 MHz (activates RACON + SART)
Which pulse length, short or long, will give better resolution at close range?
Short pulse length
Identify the following radar error + their cause: Interference
from other radars on the
same frequency
Identify the following radar error + their cause: Multiple Echoes
occurs when a short range, strong echo is received from a ship, bridge or breakwater
Identify the following radar error + their cause: Spoking
hardware display error
Identify the following radar error + their cause: Side Lobe
every time antenna rotates, some radiation escapes on each side of the beam; usually
shows at short range & from short targets
Identify the following radar error + their cause: Second Trace Echoes
echoes received from a contact at an actual range greater than RADAR range setting
Define Range Resolution
ability of RADAR to distinguish between 2 targets at the same bearing but slightly
different ranges
Define Bearing Resolution
ability of RADAR to distinguish between 2 targets side by side on same range
Ship's Head-Up relative motion radar display was the first mode to be invented.
Name 5 disadvantages of this type of display mode.
-own ship at center
-yawing will smear targets
-heading flasher points to 0 degrees
-relative bearings
-may not align with chart
What type of display mode is recommended?
North-Up, Stabilized, Relative Motion
Name advantages of Ship's Head-Up unstabilized relative motion radar display
mode.
Visual orientation matches radar orientation, can be used without sensor inputs
In order to display "true motion" on a radar display, what information must be fed
into the radar?
Gyro & speed input
How is Course-Up stabilized relative motion display different from the Head-Up
unstabilized RADAR display?
Gyro input, true bearings, stabilized ARPA display
with complete solution
What does RADAR stand for?
Radio Detection and Ranging
What are the steps to Situational Awareness?
Appraise, plan, execute, monitor, revise
Name 3 purposes of RADAR
Navigation, collision avoidance, situational awareness
Radar helps reduce uncertainty in the collision avoidance process. What other
information may be used in the collision avoidance process?
VHF radio + visual contact
What control would you use to reduce the clutter created by rain squalls?
FTC (Fast Time Constant)
What control would you use to reduce the clutter created by sea return?
STC (Sensitivity Time Control)
If your RADAR is not picking up known targets, what control should you check?
Assume no mechanical problems.
Suppression
What could be the impact of improperly tuning your RADAR?
Loss of targets, no detection
On what two frequency bands do RADAR waves transmit?
-3cm / X Band / 9500 MHz (activates RACON + SART)
-10 cm / S Band / 3000 MHz
What is the impact of own ship yaw on situation assessment on an unstabilized
radar display?
Target smear
In general, is a radar range more accurate than radar bearing?
Yes - RADAR
Which edge of the radar range ring is used to measure range (inner or outer edge
measured from the center)?
Outer
What are some of the factors that control the maximum distance a target can be
detected?
-Pulse width (power of transmitter)
-Height of Antenna
-Atmospheric conditions
-Characteristics of Target (size, shape, texture, material)
The radar's ability to discriminate between targets positioned one behind the
other is primarily controlled by what factor?
Pulse width - range resolution
The radar's ability to generate an accurate bearing resolution is primarily
controlled by what factor?
Horizontal Beam width - bearing resolution
About how many degrees wide is the typical horizontal beam width on a radar?
, 0.7 - 2.0 degrees / IMO 2 degrees
Name 4 factors which control the size of the target painted (spot size)?
-Horizontal beam width
-Pulse length
-Pulse repetition rate
-Target responsiveness
Which radar band gives the best resolution at close range?
3 cm / X Band / 9500 MHz (activates RACON + SART)
Which pulse length, short or long, will give better resolution at close range?
Short pulse length
Identify the following radar error + their cause: Interference
from other radars on the
same frequency
Identify the following radar error + their cause: Multiple Echoes
occurs when a short range, strong echo is received from a ship, bridge or breakwater
Identify the following radar error + their cause: Spoking
hardware display error
Identify the following radar error + their cause: Side Lobe
every time antenna rotates, some radiation escapes on each side of the beam; usually
shows at short range & from short targets
Identify the following radar error + their cause: Second Trace Echoes
echoes received from a contact at an actual range greater than RADAR range setting
Define Range Resolution
ability of RADAR to distinguish between 2 targets at the same bearing but slightly
different ranges
Define Bearing Resolution
ability of RADAR to distinguish between 2 targets side by side on same range
Ship's Head-Up relative motion radar display was the first mode to be invented.
Name 5 disadvantages of this type of display mode.
-own ship at center
-yawing will smear targets
-heading flasher points to 0 degrees
-relative bearings
-may not align with chart
What type of display mode is recommended?
North-Up, Stabilized, Relative Motion
Name advantages of Ship's Head-Up unstabilized relative motion radar display
mode.
Visual orientation matches radar orientation, can be used without sensor inputs
In order to display "true motion" on a radar display, what information must be fed
into the radar?
Gyro & speed input
How is Course-Up stabilized relative motion display different from the Head-Up
unstabilized RADAR display?
Gyro input, true bearings, stabilized ARPA display
