Sonardyne - Model Ranger 2 - Ultra-Short BaseLine Acoustic
From Acoustic Positioning
Ranger 2 is a high performance acoustic position reference system designed for tracking underwater targets and positioning dynamically positioned (DP) vessels. The system (commonly referred to as a HPR system) uses the Ultra-Short BaseLine (USBL) positioning method to calculate the position of a subsea target, for example an ROV, by measuring the range and bearing from a vessel-mounted transceiver to an acoustic transponder fitted to the target. Multiple subsea targets over a wide area and range of water depths can be simultaneously and precisely positioned.
Ranger 2 builds on the simplicity and reliability of Sonardyne’s original Ranger system but adds support for the latest 6G (Sixth Generation) acoustic instruments and Wideband 2 signal architecture. 6G systems offer precise acoustic ranging, fast data telemetry and hardware that is easier to set up and operate even in the most challenging subsea operating environments. These features improve the efficiency of survey operations, reduce vessel delays and generate cost savings for owners.
Ranger Product Family
Ranger 2 is available in two versions. In standard configuration, Ranger 2 allows up to 10 subsea targets to be simultaneously tracked from a surface vessel. Operating ranges of greater than 6,000 metres are achievable and the system supports all industry standard survey and DP output telegrams. One second position updates are achievable in any water depth.
Ranger 2 Pro is designed for complex operations where any number of subsea targets can be tracked. Multiple transceivers and attitude compensation sensors can be simultaneously interfaced into Ranger 2 Pro allowing for highly redundant, bespoke installations. Ranger 2 Pro also supports integration with subsea inertial navigation technologies (e.g. Sonardyne SPRINT), external triggers for acoustic synchronisation and user configurable displays.
Optimised Ranger 2
The positioning accuracy obtainable from Ranger 2 can be improved by interfacing the system directly into Lodestar, Sonardyne’s premium quality Attitude and Heading Reference System (AHRS). This configuration is referred to as Optimised Ranger 2.
In an Optimised Ranger 2 system, the Lodestar is co-located with the vessel’s 6G acoustic transceiver. The main advantage is that they are directly connected, enabling raw USBL range and bearing data to be simultaneously processed with the Lodestar’s attitude data. This integration achieves a tightly compensated solution that enables a system accuracy of 0.1% of slant range to be achieved. An Optimised Ranger 2 is therefore able to meet the positioning specifications of subsea projects that previously may have required the use of alternative acoustic positioning techniques.
Ranger 2 supports Inverted USBL (iUSBL) tracking of towfish over long laybacks. Rather than mounting the USBL transceiver on the vessel in the traditional manner, with iUSBL the transceiver is installed on the towed body itself. This method eliminates the need for repeated system calibration, whilst the accuracy and repeatability of the acoustics is improved as the transceiver is located in a low noise, dynamically stable environment.
Bridge / Instrument Room Hardware
Onboard, the Navigation Sensor Hub (NSH) is the interface between the in-water acoustic instruments, sensors and the Navigation Computer which runs the Ranger 2 software application. In addition to accurately time-stamping incoming data from external devices such as gyro, VRU and GPS, the NSH also provides power and communications for vessel’s acoustic transceiver.
The Ranger 2 software application is easy and intuitive to use, requiring only basic operator training to become familiar with it. It includes an extensive array of tools to allow the user to assess the performance of the system, including real-time acoustic quality indicators, noise analysis and signal travel time displays.
Acoustic positioning operations can be remotely monitored on a vessel network using a serial connection from Ranger 2 to Sonardyne’s Viewpoint software application. Viewpoint supports .dwg format backgrounds, on-screen guidance, measurement tools, configurable vehicle outline shapes and offsets, waypoints and geodesy.
HPT is a high performance, vessel-mounted acoustic transceiver that enables transponders being tracked with Ranger 2 to be precisely positioned. A number of different array designs are available from full hemispherical coverage to directional designs for ultra deep water and high noise operating environments. To allow tracking of long layback targets at shallow angles, a tilt adaptor enables the transceiver to keep the target being tracked within the ideal operating envelope of its array.
HPT transceivers can also be used as modems for autonomous monitoring transponder setup and data retrieval as well as supporting Long BaseLine operations when using a Sonardyne Fusion system.
The deployment method of the HPT transceiver is critical to Ranger 2’s positioningperformance. It should ideally be rigidly mounted to the vessel well below the keelaway from any weather or vessel induced aeration.
Sonardyne’s hydraulic through-hull deployment systems are extremely rigid and ideal for permanent vessel installation, whether new-build or retro-fit. For short-term projects on vessels-of-opportunity, a high quality over-the-side deployment system is available that is practical to transport and install on a vessel whilst it is alongside.
Vessel Reference Sensors
All USBL systems need to remove the effects of vessel motion upon the transceiver. To do this they are interfaced to heading, pitch and roll motion sensors of a quality appropriate to the accuracy required for the operation and water depth. Ranger 2 supports a wide range of these sensor types including Sonardyne’s own Lodestar AHRS unit which, for optimum system performance, should be mounted close to the vessel’s HPT transceiver.
Sonardyne’s GyroUSBL instrument combines a HPT transceiver and Lodestar AHRS in the same housing. With the AHRS in fixed mechanical alignment to the HPT’s acoustic array, the requirement for a total system calibration to determine the alignment of the ship’s motion sensors to the transceiver is, in many situations, eliminated. This saves operational time and vessel costs.
6G Subsea Transponders
Ranger 2 supports previous generation Sonardyne transponders, for example WSM, and many transponders from other manufacturers. However the maximum benefits of the system can only be realised when using exclusively 6G® transponders.
WMT is a small, lightweight unit generally used for tracking mobile targets such as ROVs. It features a responder trigger for fast position updates and is depth rated up to 3,000 metres.
DPT 6 is designed for DP reference and large target tracking. The unit is fitted with a highly reliable acoustic release mechanism to enable it to be deployed on the seabed in a floatation collar and later recovered to the surface without ROV intervention.
Compatt 6 is Sonardyne’s most advanced USBL and LBL transponder. Its integrated communications and navigation technology allows it to be used as a position reference transponder for DP, a multi-purpose modem and autonomous data logger.
Operating Range : >6,000 metres
System Accuracy Typical Optimised : 0.2% of Slant Range Optimised 0.1% of Slant Range Depending on the installation quality, system accuracy can vary greatly. Where every effort is made to ensure the rigidity of the deployment pole, an appropriate transceiver has been selected and the vessel’s AHRS is high quality, standard Sonardyne USBL systems have been proven to achieve 0.1% of slant range error. In 1,000 metres, this is equal to 1 metre.
Number of Targets Tracked : 1 surface, unlimited subsea
Position Update Rate : 1 second, independent of water depth
Output Telegrams : Supports all industry standard survey and DP telegrams