The DVL A50 and A125 are high performance DVLs in insanely small packages that open the door to advanced capabilities on your ROV or AUV like position holding and autonomous navigation. Each variant comes with a pre-installed WetLink Penetrator, JST GH connectors for the Ethernet and serial ports, and spade connectors for power to make integration with the BlueROV2 and other vehicles as easy as possible.

The DVL A50 and A125 are both supported in BlueOS through the Water Linked DVL extension, enabling ROV position holding and navigation to augment your piloting experience.

A doppler velocity what??

A doppler velocity logger, or DVL, measures speed relative to the seafloor by using the doppler effect. It has four acoustic transducers tilted at 15 degree angles that send and receive pulses to the seafloor.

When the vehicle is moving forward, the doppler effect causes the returned frequency to increase, and vice versa when in reverse. When measured, this effect provides an extremely precise velocity measurement relative to the seafloor.

That’s important because it enables accurate underwater positioning and measurement of small changes in position. Acoustic positioning systems like USBLs and SBLs exist, but only provide location within a few meters range – not enough to enable autonomous navigation. The DVL provides an extremely accurate velocity measurement which, when integrated over time, provides a highly accurate position estimate.

Please note that, by itself, the DVL provides relative position but to have an accurate global position, you still need a positioning system like a GPS or USBL, in addition to the DVL.

Turn on auto pilot, err, auto ROV pilot

A DVL on an ROV is the missing piece needed to enable many advanced behaviors.

The most fundamental of those is position holding, which uses the DVL to maintain a consistent position when the pilot is not providing any input. Those of you with aerial drones are used to this – take your hands off the stick and the drone holds a GPS location, even with some wind or current. It makes piloting easier and reduces the mental workload needed to complete a mission. You don’t need a GPS or USBL positioning system to benefit from position hold!

The DVL also enables features such as waypoint navigation, survey grid navigation, guided mode, and more. These features require a global positioning system, such as a GPS or USBL, or require you to manually set the starting point on a map.

As far as DVLs go, this one is revolutionary

The Water Linked DVL A50 is special as it marks a revolutionary advance in the affordability, size, and capability of DVL technology. It launched in 2020 and Water Linked has continued software development updates to continuously improve it even more.

The compact size of the DVL A50 is truly mind boggling and enables it to be used on small vehicles. You’ll barely even notice that it’s there!

The small size doesn’t mean there’s a compromise on performance. In fact, the A50 has some of the most impressive performance specs of any DVL on the market, including the best minimum range of any unit, at 5 cm. This is important for an ROV, which often works near the bottom or even touches the bottom, to make sure you don’t lose track of your position in the process.

The DVL A125 augments those capabilities with an increased range up to 125 m and 600m depth rating, making it a good choice for larger vehicles and challenging operating conditions. It’s also better at measuring high velocities up to 9 m/s, making it a good fit for fast vehicles.

An ease to integrate

The DVL comes ready to integrate in your application, whether that’s on a BlueROV2 or something else. In addition to the pre-installed WetLink Penetrator, it has JST GH connectors for the Ethernet and serial port communication options. We recommend Ethernet when possible, as it allows you to view the Water Linked configuration interface in a web browser.

Spade terminals are installed on the power wires and it can be powered from 10-30V.

If you’re using BlueOS, one-click installation of the Water Linked DVL extension provides support for the hardware and enables position hold and advanced navigation features. If you’re using it in another application, you can use the Water Linked API or PD6 protocols to communicate with the DVL.

Upgradeable for the most precise applications

DVLs are export controlled items when they have an accuracy of better than 1.0%. To avoid the required license and controls, the standard DVL A50 and A125 has an accuracy of +/-1.01%. If you require higher accuracy, a software upgrade can improve accuracy to +/-0.1%, but also requires paperwork for the appropriate regulatory license. Please contact Water Linked if you’d like to upgrade your unit!