Key Features

Incorporates Sonardyne's latest Wideband Technology

Allows survey accuracy tracking of targets to operating ranges of greater than 6,000 metres

Interfaces to most makes of DP system

Builds on world-wide success of existing USBL and LBL systems from Sonardyne

A platform for the future with upgrades easily installed by the user

Efficient equipment utilisation; allows for USBL and LBL using common vessel hardware

Compatible with existing MF frequency transponder inventories

Fusion USBL allows multiple subsea targets to be accurately positioned relative to a surface vessel.The system is particularly suited to tracking ROVs, AUVs and towfish or as a position reference input for vessels equipped with a Dynamic Positioning (DP) system.

USBL systems calculate position by combining acoustic range and bearing data from a vessel transceiver with attitude, heading and GPS sensor information. One of the main advantages of the technique is that it does not require a seabed transponder array to be deployed before positioning can commence. Only the target to be tracked needs to be equipped with a transponder or responder.

The core component of Fusion USBL is the ship-borne transceiver. This uses Sonardyne's unique plane transducer array to transmit, receive and process acoustic signals coming from transponders below. This design offers significant performance advantages over spherical transducer arrays which generally require large diameter gate valves, are mechanically complex to install and are more easily affected by vessel noise.

So that the performance of the system can be optimised to suit the vessel, water depth and operating environment, Sonardyne offers a range of ship-borne USBL transceiver options. These have an operating range of greater than,6,000 metres (proven performance) and allow tracking right up to the surface. Fusion USBL is compatible with the vast majority of Medium Frequency beacons world-wide.  This is in addition to a range of new transponders that offer faster set-up, dramatically more channels and easier servicing.

With the deployment of additional transponders and installation of the appropriate software module, a basic Fusion USBL system can be upgraded to merge any combination of acoustic positioning techniques.

A Typical USBL System

Illustrated above is a Fusion system configured for simple USBL operations such as DP reference or ROV tracking. The equipment comprises a Data Fusion Engine, USBL software, a through-hull USBL transceiver and seabed or vehicle-mounted transponders.

DP Reference
In this application, a single reference transponder is deployed on the seabed and its position, relative to the vessel, is reported to the DP computer. The vessel is then automatically maneuvered so that it remains on a constant heading and in a constant position whatever the disturbing forces of wind, current and wave action.

Fusion USBL can be interfaced to most current makes of DP system and can be supplied as a cost-effective upgrade for an existing acoustic reference system or completely new vessel installation. Despite the hostile acoustic environment beneath large DP vessels, with thruster activity generating high levels of noise, the system can maintain stable and reliable positioning with fast update rates.

ROV Tracking
Here, a transponder or responder is fitted to an ROV, towfish or other mobile target and its position and depth is tracked relative to the surface vessel. The software supports tracking of multiple, mobile or stationary targets and can provide an output telegram to allow ‘follow-ROV’ operating mode when interfaced to a DP system.

Overall, the system has a proven accuracy of 0.27% 1 Drms slant range with 63% of fixes within a 2.7 metre radius in 1,000 metres of water. Fusion USBL transceivers can provide a range accuracy of better than 0.2 metres and positioning repeatability of better than 0.1% of slant range.