Key Features

Pitch, Roll and Heading corrections to be entered into the USBL system

Grid sound velocity and the antenna x, y offsets with respect to the transceiver

Easting, Northing and Depth of the reference beacon

Adobe Acrobat PDR report format

Advantages of CASIUS processing:

Estimate of transponder position and sound velocity are unbiased

Processing visibility at each stage

Antenna offset from Transceiver is an output

Weighted matrices account for USBL errors and bad data therefore there is no need for an operator to edit data

Reports are simple and graphic

Roll, Pitch and Heading corrections output exactly as they should be entered into the USBL system

Datasheet

CASIUS

Sonardyne's CASIUS (Calibration of Attitude Sensors In USBL Systems) is a Microsoft Windows based software application that optimises the performance and accuracy of Ultra-Short BaseLine (USBL) acoustic positioning systems by accurately calibrating a vessel's attitude sensors such as Gyros and Vertical Reference Units (VRUs).

The process starts by deploying a reference acoustic transponder on the seabed. Next, the vessel sails in a pre-determined calibration pattern over and around the transponder whilst simultaneously collecting DGPS, USBL, VRU and Gyro Compass data. During this process, the data is logged by the USBL system and CASIUS application for post-processing.

Once the vessel has performed its calibration pattern over the seabed transponder, the DGPS and USBL acoustic range data is processed by CASIUS to compute an unbiased estimate of the reference beacon position, the grid sound velocity and the antenna offsets.

USBL data is then compared with predicted data from the DGPS/ reference transponder to estimate the pitch, roll and heading errors. This process is repeated until the result is optimised.

Technical Bulletins