Underwater GPS

You will typically experience an acuracy of ~1% of the range between the Locator and the Receivers. On 100 meter range, you can expect an acuracy of ~1 meter.

Underwater GPS relies on acoustics to transmit data through the water. Acoustic transmission can be affected by these scenarios:

  • Reflections from hard surfaces nearby your operation area (ship hulls, the sea floor, constructions etc.)
  • Signal dampening from objects in the water (large consentrations of fish etc.)

The Water Linked technology has revolutionary performance in these kinds of challenging scenarios. While other solutions simply break down, Underwater GPS continues to work. With Underwater GPS you should simply expect somewhat lower acuracy in such operations.

An acoustic reflection occurs when sound travelling through water hits an object and bounces back. The harder and flatter the surface is, the stronger the reflection will be.

Underwater GPS use triangulation as one the methods of aquiring the position of the Locator. To triangulate, you need at least 3 Receivers. We always recommend to use 4 Receivers for increased accuracy.

Make sure to spread the receivers out with at least some meters separation between them.

The current version of the GUI software has support for 4 Receivers.

The Explorer Kits are set up with connectors for 4 Receivers.

To be future proof, we have built in support for up to 7 Receivers in the Master-D1.

In principle, only the small Receiver-head needs to be under water. But this is far from ideal. We recommend to move them down to 2-4 meters below the surface. The reasons for this are:

  • They will be well below the surface area where there might be lots of air bubbles from waves etc.
  • They will be well away from the boat and the surface which in themselves generate a reflection.

The receivers does not in any way need to be on the same depth. It may actually be positive to have them with a little separation also here. Just make sure to update your Receiver configuration in the GUI!

Currently we support 1 Locator per Master-D1.

In the future we will launch support for more Locators per Master-D1. If you have specific requirements, please contact us and tell us about your application!

The software doing the search algorithms does not try to look for a Locator outside the 100 meter range. So when a Locator travels outside 100 meters, it will not be positioned anymore. You might see the position starting to move back to Origo (the location of your top-side Master-D1/Explorer Kit).

When the Locator comes back in range, it will immediately show up in the GUI again.

All our acoustic modules are sertified for 300 meters depth. They have been tested well below this, but to add some margins, we have set the limit to 300 meters.

The Locator-U1 is an exception. This module is depth rated to 100 meters.

You only need to take it a few centimeters below the surface to get its position.

The search area is actually a half cube of 200 meter wide x 200 meter long x 100 meter down where the Receiver baseline is placed in the placed in the middle of the horisontal square of 200 x 200 meters. When the Locator is in the corners of the qube, you will actually see a range of well above 100 meter from the Receiver baseline.

To be able to triangulate the Locator, you need to spread the Receivers out with a few meters separation between them. This spread of Receivers is called the “Baseline”.


Underwater GPS

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Configuration is reset when upgrading, please verify that the receiver positions and other config is correct.

This can be caused by:

  • Locator is out of range (or configured too short). => Increase range
  • All receivers being on a line (it is then un-determined which side of the line the locator is on) => Place one receiver out of the line, or change range to only search one side of the “Line”
  • Strong echo sounders are using the same ultrasonic frequency as the Underwater GPS => Change the carrier frequency