Getting up to speed on the Easytrak USBL product range

Very simply, an Ultra Short Base Line (USBL) system is a method of positioning subsea, whether its an ROV, towfish, diver, or the vessel itself. A USBL system consists of a transceiver which is mounted on a pole under the vessel, a beacon which is mounted on the item you are interested in tracking and a topside computer system which calculates the range and bearing measured by the transceiver.

applied acoustics have been manufacturing survey grade USBL systems since 2010. Our Easytrak USBL family comprises our entry-level Alpha system right up to our newest member, Pyxis. Nexus 2 and Pyxis systems are both survey-grade solutions for positioning and navigation subsea within vital marine sectors, such as: Oil and Gas, Renewables, Defence, Ocean Science, Aquaculture, Port and Harbour Surveys and UXO Surveys and Clearance.

Here’s what you can find in this guide:

• What is the Easytrak USBL line-up? 
• What are the recent developments? 
• What were the systems’ accuracy levels and what are they now?
• How does this benefit customers? 
• How do I select suitable beacons for my application? 

What is the Easytrak USBL line-up?

There are a number of different systems within the Easytrak USBL family, each of which have their place. First is our Easytrak Alpha system which suits shallow water surveys; this is followed by the Easytrak Nexus 2 Lite system, and then the very successful Nexus 2 itself. The line-up is completed by our newest and highest grade USBL + INS system, Pyxis.

What have been the recent developments?

Our engineering team have been working hard to improve the accuracy and performance of our entire Easytrak USBL product offering. A new transceiver has been designed for the Alpha system, the 904C, which has increased the accuracy from 3.5% to 3% of slant range. The previous Nexus Lite system has been replaced with the Nexus 2 Lite, utilising the 2686 transceiver (previously part of the Nexus 2 system), which has increased the accuracy from 1% to 0.45% of slant range. And finally, the Nexus 2 and Pyxis omni-directional transceivers have been redesigned and now include 7 internal elements instead of the previous 5, further improving accuracy and all-round performance.

What has changed?

As mentioned, all developments by our engineering team have made our entire family of USBL systems better performers in terms of the slant range system accuracy. Replacing the 903C, the new 904C is manufactured from marine grade stainless steel and has an improved acoustic slant range accuracy of 3%, while an upgraded compass fitted inside the 904C improves the repeatability of results.

The Nexus 2 Lite system has been completely upgraded from the previous Nexus Lite system, with a new user interface and added compatibility with our 2686 transceiver, giving a 0.45% slant range accuracy. The Nexus 2 Lite system now supports applied acoustics’ Sigma 2 protocols, proven to improve position stability and range repeatability. The Nexus 2 Lite also increases the number of trackable targets from 8 to 10. These changes have precipitated new software and an updated console for use with the reliable 2686 transceiver.

Previous Nexus 2 and Pyxis systems fitted with the 2686/3781 omni-directional transceivers had a slant range accuracy of 0.45%. The new 7-element 2782/ 3782 transceivers have further increased the slant range accuracy to 0.25%.

How do these changes benefit our customers?

The Alpha system now has an upgraded 904C transceiver, which is smaller than the 903C predecessor and features a rugged stainless housing. The compact form not only allows for less motion in free hanging applications, which can improve accuracy, but also allows deployment by a single person and easy, cost-effective transportation. This makes the 904C ideal for small ROV or diver tracking and instant mobilisation on smaller vessels of opportunity.

The 904C power supply and receivers have been redesigned to reduce noise and improve the target signal detection, which in turn improves the repeatability of position. A new, more accurate compass allows for motion compensation to improve accuracy when using the 904C standalone without external sensors. 

Easytrak Nexus 2 Lite incorporates Sigma 2 Spread Spectrum technology to provide a secure acoustic link. The Sigma 2’s wide bandwidth transmissions reduce the system’s susceptibility to interference. This provides our customers with an accurate and stable positioning system that is easy and intuitive to operate. A geo-referenced graphical overlay can be offered as an optional extra, which is typically used when operating near shore or surrounding structures like wind farms. 

The fact that the Nexus 2 Lite is a high performer at a low cost makes it a standout USBL system when it comes to a number of different applications, such as underwater survey and inspection, subsea construction sites, cable and pipeline route surveys, hydrographical and geotechnical surveys and nearshore construction and salvage operations. 

How do I select suitable beacons for my application?

The best way to choose the most suitable beacon for your application is to check out the different beacon options on our website. All our Easytrak USBL systems are compatible with all of our different types of beacon. 

If, for example, you wanted to track divers, you will know how deep and how far away from the vessel they could go, and therefore what range you’ll need the beacon to operate to. You will also know that as the beacon will be fitted onto a diver, you won’t want it to be heavy. It’s therefore safe to say the best beacon for diver tracking would be our Micro Beacon. But we have all kinds of beacons for all ranges and use cases.

With the increase in the amount of targets Nexus 2 Lite can now achieve, we are providing greater flexibility across the whole range. This means a customer will not necessarily need to go to a higher-rated or deeper system just so they can track their required number of targets.

Get the right system for your work

If you are in any doubt or would prefer to discuss your options with a member of the team, simply call or email our office. We will be more than happy to talk over what’s needed for your projects and help you find exactly the right system for your needs.