The standard multibeam calibration, run after installation and whenever the system is disturbed. Specific line pairs isolate each error: one line run at two speeds over a slope for latency, reciprocal lines over a slope or feature for pitch, reciprocal lines over flat seabed for roll, and adjacent parallel lines past a feature for heading (yaw). Results go into the vessel configuration and are checked again on the first production lines.
Patch test this morning off the breakwater, roll came out at minus 0.12 and yaw at 0.6.
Solve latency first, then pitch, then roll, then yaw: each step assumes the earlier biases are already removed.
Also heard as
- calibration
- patch
- calibration lines
Related terms
Roll
Rotation of a vessel about its fore-and-aft axis, measured to correct the angle of every sonar beam.
Pitch
Bow-up or bow-down rotation of a vessel, which shifts sonar footprints forward or aft along the track.
Latency
A time delay between when a sensor measures something and when that measurement gets its time stamp.
Pole mount
A sonar transducer fixed on a rigid pole over the side or bow of a boat instead of built into the hull.
Lever arms
The measured distances between sensors on a survey vessel, used to carry positions and motion to each sonar.