The values entered here will be used in the calculation of Total Propagated Uncertainty (TPU). TPU is derived from a combination of estimates of the accuracy of each individual sensor, estimates such as.
• nav/gyro/heave/pitch/roll/tide errors
• latency error estimate
• sensor offset error estimates
These uncertainty estimates are combined with individual sonar model characteristics in DeviceModels.xml to calculate horizontal and vertical uncertainty values for every sounding along a track line when TPU is applied
Sensor accuracy values for various sonar types can be viewed on the TPU Computation Resource page of the CARIS web site www.caris.com/tpu.
Sensor accuracy values for TPU must be entered as 1-sigma.
1. Expand the TPU section of the HVF by clicking the + icon.
2. Type data as needed in the Offsets section:
• MRU to Transducer: The physical offset in three dimensions from the motion recording unit to transducer 1 on the vessel.
• MRU to Transducer2: The physical offset in three dimensions from the motion recording unit to transducer 2 on the vessel.
• Navigation To Transducer: The physical offset in three dimensions from the navigation antenna to transducer 1 on the vessel.
• Navigation To Transducer2: The physical offset in three dimensions from the navigation antenna to transducer 2 on the vessel.
• Transducer Roll: The mounting roll offset for transducer 1. The offset is positive when rotating the transducer away from starboard (starboard down).
• Transducer Roll 2: The mounting roll offset for transducer 2. The offset is positive when rotating the transducer away from starboard (starboard down).
3. Uncertainty values used Type data as needed in the Standard Deviation section:
• Motion Gyro: The measurement standard deviation of the heading data in degrees.
• Heave % Amplitude: An additional heave standard deviation component that is the percentage of the instantaneous heave.
• Heave (m): The measurement for standard deviation of the heave data. Most heave manufacturers quote heave error as being determined from StaticHeave or PercentageOfHeave depending on which value is larger.
• Roll: The measurement standard deviation of the roll data in degrees.
• Pitch: The measurement standard deviation of the pitch data in degrees.
• Position Nav: The standard deviation associated with the measurement of positions for the vessel. This is usually the error of the GPS sensor being used.
• Timing Trans: Standard deviation in transducer time stamp measurement.
• Nav Timing: Standard deviation in navigation time stamp measurement.
• Gyro Timing: Standard deviation in gyro time stamp measurement.
• Heave Timing: Standard deviation in heave time stamp measurement.
• Pitch Timing: Standard deviation in pitch time stamp measurement.
• Roll Timing: Standard deviation in roll time stamp measurement.
• Offset X: Standard deviation for the X measured offset on the vessel.
• Offset Y: Standard deviation for the Y measured offset on the vessel.
• Offset Z: Standard deviation for the Z measured offset on the vessel.
• Vessel Speed: The standard deviation for the vessel speed measurements.
• Loading: Vertical changes during the survey because of fuel consumption, etc.
• Draft: The standard deviation in the vessel draft measurements.
• Delta Draft: The standard deviation in the dynamic vessel draft measurements.
• MRU Align StdDev Gyro: This value is the uncertainty of the motion recording unit placement within the vessel fixed coordinate frame.
• MRU Align StdDev Roll/Pitch: This value is the uncertainty of the motion recording unit placement within the vessel fixed coordinate frame.
• Comments: Any additional information.