SeaTrac USBL Positioning System

What is a USBL system?
Installing the X010 USBL Beacon on the Blueye ROV
Getting started with Blueprint Subsea PinPoint V2

What is a USBL system?

An acoustic positioning system can be used when you need to know the location of the ROV for extended periods of time. USBL is short for Ultra Short Base Line, which indicates the distance between each transducer (1-2 cm) in the USBL Transceiver head, as opposed to Long Base Line (LBL), which can have 100 m to 1 km between the transducers. The USBL system measures distance and direction to the ROV, which gives us a relative position estimate. By knowing the position and orientation of the topside transceiver, we can then calculate a global position. So the precision of the position and orientation of the transceiver is a critical factor for the final position estimate. Other sources of error can be caused by multipath, where the sound waves get reflected on hard surfaces or the sea surface. So it's important to think about the line of sight and try to minimize possible reflections to optimize your setup.

In this guide, we will show you how to install the USBL beacon onto the ROV and how to get started in the PinPoint software from BluePrint.

Installing the X010 USBL Beacon on the Blueye ROV

Start by powering off the ROV, removing the side covers, and the buoyancy parts.

Remove the nut from the handle.

Remove the nut and shim.

Attach the clamp ring by using the existing long screw.

Insert buoyancy parts in the battery cover.

Find the forward center mark. Align with forward on the ROV.

Attach the X010 beacon inside the clamp ring.

Lubricate the cable to ensure a waterproof connection.

Attach the connector to the X010 beacon.

Insert the Guest Port connector.

The Seatrac USBL beacon is compatible with all Guest Ports (GP1, GP2, GP3).

The wiring should be as shown above, so there is space for the buoyancy parts.

Install the Starboard side buoyancy and side cover. Check that the beacon cable is not squeezed.

Place the Port side buoyancy.

Put on the other side cover, and make sure no cables get squeezed and that it closes properly. The installation of the USBL X010 beacon is now complete.

Getting started with Blueprint Subsea PinPoint V2

1. Install the Software and connect the wires

Download and install the PinPoint v2 software on the topside Windows computer and open the program.

Connect the power cable from the wall socket to the Transciever's power cable and insert the USB cable into the computer. You should now see the Transciever icon go from red to yellow. You can also click this icon to calibrate the compass of the transceiver or change the operating range.

Click yes on the initial prompts regarding "Reduced ping delay", and update the transceiver firmware.
This enables a faster update rate of new position estimates.

Firmware update in progress.

Warning! This update reconfigures the transceiver ID to 1 instead of 15, which was used in PinPoint V1. Therefore, if you need to run on V1 after this update, you will need to reconfigure the ID manually using the Seatrac Tools program.

2. Mount the USBL Transceiver

Place the USBL transceiver in the water. Try to get some distance from the quay wall, and approximately 2m below the surface. A pro tip is to mark the cable with a piece of tape to make it easier to see when you have reached the desired depth. You also typically get a better position when the ROV is operating below the transceiver, rather than close to the surface.

A simple knot can be used to secure the transceiver from running out.

3. Configure Platform setup

Click on the Transceiver icon and the ship icon to open the Platform Setup Dialog.

Here, you select between using a fixed coordinate or GPS from the input devices.

You can also select the heading source with the following options:

Internal compass
Fixed heading (manual value)
External GNSS compass (recommended for higher accuracy).

In our setup, we rely on a fixed heading as the magnetic field is quite disturbed in this area, and we are stationary. Click on the checkmark to save the settings.

4. Add the Acoustic Beacon

Click on the "Add Beacon" icon on the bottom left.
Click on the + icon and select an ROV.
Enter the last 6 digits of the serial number on the tracking beacon. This can be seen from the outside of the ROV. In our case: 016840
Click on the checkmark to save the settings.

5. Deploy the ROV

Power on the ROV and lower it into the water.

6. Start live tracking

Set transceiver location:
Stationary operation:
Click on the map icon in the left menu, and right-click on the map where the transceiver is placed. Hit "Fix Position here".

Operating from a vessel:

Operating from a moving platform requires using the USB-GPS in the kit or an external NMEA GPS from the vessel, as selected in step 3 above.

Click on "Start Tracking" in the top left corner.

You should now see the ROV on the map, and the signal strength in the top left.

Adjusting the fixed Heading manually:

If the transceiver’s orientation in the water is unknown:

Fly the ROV to a known location on the map.
Adjust the fixed heading orientation of the transceiver in PinPoint by testing values between 0–360° until the ROV’s position matches the map.
Verify by flying the ROV to another known location and checking alignment.

You can find the "Setup Platform" settings from this view as well by clicking the downward arrow in the top center, and the ship icon.

Once the settings are applied, you will see the ROV shift position immediately.

Publishing Position to Blueye ROV

The PinPoint software can also output the position data as NMEA sentences over UDP. The Blueye ROV can then use this as a position sensor and fuse it with other available sensors to get a better position estimate of the ROV. You'll also get the benefit of having accurate position data in the divelog, enabling georeferenced images and videos, along with dive tracks that are automatically timesynced with all the other sensor data.

You will also get to see the ROV on the map inside the blueye app, and can use the "Points of interest" to enter known locations (targets) or add new findings on the fly. This also makes it possible to use the mission planner to dive autonomously to your Points of interest.

Click on Add output device, and select NMEA Network Output.

Make sure you are on the Blueye surface unit’s Wi-Fi, and click on the right arrow icon for more advanced settings.

Select UDP, Wi-fi (broadcast), port: 10110, and turn off heading. Turn off the "Local Beacon" and select the ROV Beacon. Disable all NMEA sentences, but keep the GLL one. Settings should look like the screenshot above.

You can now see the ROV position automatically update itself in the Navigation tab inside the blueye app.

When the NMEA is successfully configured, you should see the NMEA input light up green in the list of Navigation sensors.

Add custom alarms

It is also possible to add custom alarms based on a geofence, for instance.

Click on the G icon in the bottom center, and draw your safe area.

Click on alarms in the left menu, and hit add new alarm. Now you can select the geofence alarm and choose between warning or critical.

List of added alarms.

As the ROV leaves the safe area, we now get a warning, as seen at the top of the screen above.

When out of line of sight

If the ROV goes out of line of sight, you will see that the position updates stop, and the link reception icon is grayed out. You will also see that the number of attempts will increase until you get back into line of sight.

Warning! Do not power the SeaTrac system for more than 15 minutes while out of water (per the SeaTrac manual).

Avoid Out-of-Water Operation
SeaTrac Beacons are designed for use in water. Extended periods of in-air transmission (greater than 10-15 minutes) may result in undissipated acoustic energy, causing internal heating and possible long-term damage to the main transmitter transducer ring. Larger current consumption and current surges may also be observed on switch-mode power supplies during out-of-water transmission.