
Applied Acoustics has been producing survey-grade USBL systems since 2010. The Easytrak USBL family ranges from the entry-level Alpha system to the most advanced model, Pyxis.
Both Nexus 2 and Pyxis are survey-grade solutions designed for positioning and navigation in essential marine sectors such as oil and gas, renewables, defense, ocean science, aquaculture, port and harbor surveys, and UXO surveys and clearance.
An Ultra Short Base Line (USBL) system is a method for positioning underwater, whether for an ROV, towfish, diver, or the vessel itself. A USBL system includes a transceiver mounted on a pole beneath the vessel, a beacon attached to the item being tracked, and a topside computer system that calculates the range and bearing measured by the transceiver.
The Easytrak USBL Lineup
The Easytrak USBL family consists of several systems, each designed for a specific purpose. The lineup starts with the Easytrak Alpha system, which is suited for shallow water surveys. Next is the Easytrak Nexus 2 Lite system, followed by the highly successful Nexus 2. The range is completed with Easytrak’s newest and highest-grade USBL + INS system, Pyxis.
Recent Developments
The engineering team has been dedicated to enhancing the accuracy and performance of the entire Easytrak USBL range. The Alpha system now features the newly developed 904C transceiver, improving accuracy from 3.5% to 3% of slant range. The previous Nexus Lite system has been upgraded to the Nexus 2 Lite, incorporating the 2686 transceiver (previously part of the Nexus 2 system), which has enhanced accuracy from 1% to 0.45% of slant range. Additionally, the Nexus 2 and Pyxis omni-directional transceivers have been redesigned, now featuring seven internal elements instead of five, leading to improved accuracy and overall performance.
Key Enhancements
All recent advancements have resulted in improved slant range accuracy across the Easytrak USBL product line. The new 904C transceiver replaces the 903C and is constructed from marine-grade stainless steel, enhancing acoustic slant range accuracy to 3%. An upgraded internal compass in the 904C improves result reliability.
The Nexus 2 Lite system has been completely upgraded, introducing a new user interface and compatibility with the 2686 transceiver, achieving a 0.45% slant range accuracy. Additionally, it supports Applied Acoustics’ Sigma 2 protocol, which enhances position stability and repeatability. The system now tracks up to 10 targets, an increase from the previous limit of 8. These enhancements have led to new software and an upgraded console, optimized for the 2686 transceiver.
Previously, Nexus 2 and Pyxis systems equipped with the 2686/3781 omni-directional transceivers had a slant range accuracy of 0.45%. The latest 7-element 2782/3782 transceivers have further refined this accuracy to 0.25%.
Customer Benefits
The Alpha system now features the 904C transceiver, which is more compact than its predecessor, the 903C, and housed in durable stainless steel. Its compact form reduces motion in free-hanging applications, improving accuracy, while also allowing for single-person deployment and easy transport. This makes the 904C well-suited for small ROV or diver tracking and instant mobilization on smaller vessels of opportunity.
The 904C power supply and receivers have been redesigned to reduce noise and enhance target signal detection, resulting in better position repeatability. Additionally, a more precise compass allows for motion compensation, improving accuracy when using the 904C independently without external sensors.
Easytrak Nexus 2 Lite integrates Sigma 2 Spread Spectrum technology, providing a secure acoustic link. Sigma 2’s wide bandwidth transmissions reduce susceptibility to interference, ensuring a reliable and stable positioning system that remains easy to operate. A geo-referenced graphical overlay is available as an optional feature, often used in nearshore operations or around structures such as wind farms.
The Nexus 2 Lite USBL system excels in various underwater applications, including surveys, inspections, and construction, due to its affordability and high performance. Its versatility makes it ideal for cable and pipeline route surveys, hydrographical and geotechnical surveys, and nearshore construction and salvage operations.
Choosing the Right Beacon for Your Application
Selecting the most appropriate beacon depends on your specific requirements. All Easytrak USBL systems are compatible with a variety of beacon types available on the Applied Acoustics website.
For instance, if you need to track divers, you should consider how deep and how far they will be from the vessel to determine the necessary beacon range. Since a beacon attached to a diver must be lightweight, the Micro Beacon would be the most suitable choice. However, there are beacon options available for a range of operational depths and conditions.
The Nexus 2 Lite’s ability to track more targets enhances flexibility across the product range, ensuring customers can effectively meet their operational needs without necessarily upgrading to a higher-tier system. This means customers may not need to invest in a higher-tier system simply to track additional targets.
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