Home        Store        Docs        Blog

New Product: The Water Linked Underwater GPS System!

(Oystein Skarholm) #21


Does the system allow for saving of routes/tracks? And if so, in what format can the trackpoints be exported? And finally, what information is being saved in the file, ie. Depth, temp, lat/Long , Northing / Easting ?

(Erlend Trøite) #22

Hi Oystein

Yes. The GUI will provide functionality for recording the track-points for a certain mission.

The record will at least contain the following information:

  • global position (lat/long) of the master electronics (top side)
  • orientation (compass course) of the master electronics (top side)
  • position x, y and z (in meters) of the locator relative to the master electronics
  • global position (lat/long) and depth of the locator (under water)
  • time-stamp
  • temperature at locator

The record can be exported (downloaded) to a .csv file, but we can add support for other formats if desired.

Notice that all this i work-in-progress and will be documented in the near future!

(Marcus) #23

Hi guys, this looks very exciting, congrats. Will it be possible to relay/display the GPS coordinates on qgroundcontrol?

(Rusty) #24


Absolutely, we had that functionality working during our initial testing and it will be even better once released. It’s incredibly helpful to see the ROV moving around on a map while you’re driving.


(pastanapolitana) #25

Hi Torgeir
On my workclass ROV, we are using just powered beacons to track the vehicle, either through power cable or even batteries. would it be possible to develop same as I’m not using bluerobotic tether with dedicated wires for it? keeping a eye on your progress…

(Torgeir Trøite) #26

Hi. Yes, it is possible to make beacons (or Locators as we call them) that only needs power or batteries with no other connections. For now you will be required to have at least one spare wire pair in your tether dedicated for the Locator. For some applications retrofitting the Locator cable on to the tether can also be a solution for those of you that does not have any spare wires in your tether.


(Tim Pierce) #27

Do you happen to have the dimensions of the board available? Specifically the mounting hole spacing, hole size and the overall height of the unit? I’m trying to future proof my tether spool, and one of the potential additions would be some sort of enclosure for the circuit board. Also does it need dedicated power, or can it take 5v via a USB port like the Fathom X boards?

Are the probe connectors to the 4 units that go in the water at the boat end connected via RJ-45 plugs?

(Torgeir Trøite) #28

Hi Tim. Have a look at the attached diagram. It shows the board dimension, mounting hole position and dimension and top/bottom build height.

The system requires a dedicated 10-18V input power. The 4 receivers are connected to the housing with Binder connector, not RJ45. We changed to a smaller and better connector.

(Torgeir Trøite) #29

Posting a conversation with Sven that might be helpful for others as well

Hi Torgeir,
I read the topic about the new “Underwater GPS System” from here1 and I also visit you website but I have still some question to you, I don’t find an answer for.
I am from the University of Rostock in Germany and we need a small equipment from getting the position of our underwater vehicles for control purposes.

Here my questions:
How precise is the system? I read that you post 1 % of the distance from locator to receiver but you also wrote that it depends on many different aspects. So what are this aspects and how are you empirical values for using this system in the field and in the laboratory based on the precision.
I saw that you system consists of four receivers and one locator. Is there a special arrangement of how I need to setup the four receivers? Is it part of the installation process to program where the receivers are and how fare they are away from each other or is there a required arrangement?
You say that the system is really robust against noisy environment, that is go but I ask myself how robust is the system against reflections? To example if I want to use the system in a small swimming pool I think there are a lot of acoustic reflections which can influence the system, have you experience with this kind of environment and how well the system works under such conditions?
Is it possible to use the system also without a gps fix inside buildings (indoor swimming pool)?
How fast is the position update rate of the system?

I think your company is a small start up company, so where the knowledge comes from and how long are you developed and test the system?

It would be really nice if you could answer my question because I should present your system on a meeting on Wednesday.
Best Regards

Hi Sven. Thank your the questions. I will try to answer all of them.

Precision: How you place the receivers will affect the precision. The GUI comes with a “heatmap” tool that estimates the precision depending on how/where you place the references (receivers). This tool will help you with the reference placement. With about 3-4 m reference separation we typically get a precision of 2-3m at 100m. Background noise, like echo sounders and sonars can also affect the precision.
Receiver arrangement: Yes, the receivers have to be placed with a few meter separation to get a good coverage. The position of the receivers (relative to a defined origo) must be written to the system. This is done through the web GUI or the API.
Robustnes: The system works fine in swimming pools. The swimming pool is a worst-case scenario for reflections, but the system does handle this type of environment!
GPS: Yes, you can use the system without GPS fix. You can run on only acoustic position and get relative positions without GPS references
Update rate: The update rate is 4 Hz.
Company: Water Linked is 4 years old, and we have been working on this technology since it’s start-up. The engineers have decades of experience from ultrasound and radar applications.

We are working on a video that shows how to configure and use the system, and I will post information on this forum when it is ready.

Best regards,

(Tim Pierce) #30

Thank you!

Do you happen to have a picture or a model number of the Binder connector? I’m looking for some sort of Panel Mount waterproof connector I can build into the wall of a waterproof 3d printed box. Ideally it would be the same connector to avoid having to make adaptors. For the tethr end of the future theoretical USBL connection i’m just using a waterproof 2 pin panel mount connector with an indexing flange in the box for the Fathom X board. I’m debating either making a standalone enxlosure box of some sort, or mounting a dedicated one on the bottom of the tether spool center frame in the available space there. If it’s waterproof and sufficiently shock mounted, it should be fine.

(Torgeir Trøite) #31

The D1 interface (used on Receiver-D1 and Locator-D1) is specified for both Binder and GH connector. The housing (Pelicase) is equipped with a Binder connector, while the Master-D1 electronics comes with a GH connector. The following snips are from our D1 specification, and shows both the connector part numbers and pin definition.

(Torgeir Trøite) #32

(Tim Pierce) #33

Perfect, thank you. Thats what I was looking for.

(Tim Pierce) #34

Another question if you have a moment to answer it. What is the diameter of the Rov mounted transponder thingy and how much of the main body can be covered by a mounting bracket. Specifically, if I were to drill a hole in the top of one of my Rov float covers and poke the transponder out through the top, how far out would it need to be exposed to function?

Also do you have plans to offer a permanent through hull mount for the boat transmitters? Can they be painted with anti fouling paint and still work?

(Torgeir Trøite) #35

Locator-A1 diameter is 20 mm
Locator-D1 diameter is 30 mm

Like any other antenna, the transducer head should be mounted so it is visible to the receivers (as much as possible) to get good acoustic coverage. The mounting bracket can cover the body, but should not cover the transducer head (the front cylinder). It will function as long as the head is out in the water, but you can experience “shadowing” if the transducer does not have a good line-of-sight to the receivers.

Painting the transducer head can reduce the gain. It depends on the acoustic properties of the paint, and how it matches the acoustic impedance of the water. I have never tested it, but I would expect maybe 1-2 dB extra loss. Not significant in it self, but when you have a lot of these factors it is not good for the performance. Also, I am not sure how it would react chemically…

(Tim Pierce) #36

Thank you! It looks like my plan will work, now I just have to save up enough money to buy one someday.

(Ian) #37

Hi Torgeir. Just curious whether there have been any changes since May that might affect the precision of around 2% to 3% at 100m depth? Also, have you done any testing at depths greater than 100m?


(Torgeir Trøite) #38

Hello Ian. A little clarification about the terminology first. The range of the Underwater GPS is 100m. This means the Locator can be up to 100m away from the Receivers, in any direction. The depth rating of the acoustic elements (the Receiver and Locators) are 300m. But to use the system at 300m you will have to build the Master into a watertight enclosure and lower the entire baseline to that depth. Typical application would be for a fixed subsea installation with Ethernet connection to topside. And then there are limits to the cable lengths. For A1 interfaces, this is 300m. D1 interface supports up to 100m cable lengths.

I hope this will help clarify more than it confuses… :slight_smile:

Have a look in the User Manual, http://waterlinked.com/wp-content/uploads/2017/08/W-DN-17002-2_Underwater_GPS_User_Manual.pdf

We are today(!) releasing a new SW version. We did some tests, and the performance looks very good. To achieve a position accuracy better than 2-3% you can increase the size of the baseline. Meaning, if you can place the receivers with a separation of say 50m you can probably expect around 1% accuracy at 100m range.

Just for curiosity…what is your intended application?

(Ian) #39

Thank you for the clarification, Torgeir. We don’t have a specific application - was passing along a query from a potential customer in Australia who was very interested in your 1% accuracy estimate. We got confused when a later post said 2-3% accuracy so we appreciate your explanation.


(ouahib) #40

We received the underwater system.
how does work the A1 locator?
Like a multidirectional piezo and send sound received from the master by the green and white wire or RS232/485 signal.
Because we want to use it through fiber optic cable and on the fiber optic we only have rs485 and RS232 signal possibilty to transfer.

thank you