This dialog box contains options for converting horizontal tow fish layback or tow cable length distances in side scan data. There are also options for reading the dynamic depth information for a remote operated vehicle (ROV).
9. To recompute side scan towfish positions in HIPS with the recorded horizontal layback or tow cable length data, select Convert Layback /Cable Out.
10. Select one of the following options:
• from Layback field: The distance from the vessel towpoint to the towfish.
• from Cable Out field: The length of the tow cable to the towfish.
11. If you selected Cable Out, enter a number in the Multiplier box to correct for integer value recording, if necessary.
If you have stored sensor depth data in an auxiliary field, you use it to calculate sensor depth. Sensor depth in this case is equal to the value in the field minus the sensor height.
12. Select the Calculate Sensor Depth check box.
13. Type the number of the auxiliary containing the total measured depth.
GPS Height
The total measured depth and the digitized height of the towfish are used to compute the depth of the towfish below the waterline. The towfish depth can then be combined with the tow cable length data and the vessel's tow point configuration to compute the position of the towfish.
The GPS Height field indicates the source of the GPS ellipsoid height data. The source options will vary depending the option set in the Ship Navigation field selected in Step 7 of the Triton XTF conversion.
• If ship navigation in the Ship Navigation field is being read from the Raw Navigation Records, then the GPS height is set to Raw Navigation Records, and cannot be changed.
• If Ship Navigation is set to Position Data Records, the GPS height control shows only RTK Packets, and cannot be changed.
• If Ship Navigation is set to Header Navigation Records, the GPS Height is set to Header Navigation Records, and cannot be changed.
For all other Ship Navigation selections, the options available for the source of GPS ellipsoid height data are the RTK Packet and the Ocean Tide field.
14. If data is being collected from an ROV (Remote Operated Vehicle), click the check box to enable the source options for measurement of vehicle depth.
The auxiliary and sensor depth fields are enabled.
15. Click the appropriate check box to select a source for reading ROV depth data:
• Auxiliary
• Sensor Depth
16. Type the number of the Auxiliary field (from 1 to 6), if this option is selected.
17. Click Next to go to the final step in the conversion process.