S/N in highly reflective environment

I just received my Waterlinked Underwater GPS, which I intend to use as a static positioning system mainly in tanks. I saw the performance in accuracy of this system in tanks, and was amazed so I bought one.

I have a 2,5m diameter round metal tank, in which I’m testing the system. I placed the 4 receivers at maximum distance to eachother. It’s very similar to this yt video: Water Linked Underwater GPS: Position Hold with BlueROV2 - YouTube . Difference is I’m using the D1 locator, because I don’t want to integrate it into the ROV. The problem for me is the accuracy: In my setup the position jumps around about 4 meters (that’s too big in a 2,5 m diameter tank!). In the diagnostics screen I see high noise base (135 to 150), so the signal has trouble peaking above this.

I realize my setup is pushing the limits on this kind of acoustic positioning, but this is exactly what is advertised Waterlinked can handle well. I tried changing the carrier frequency to no avail. I think the problem is the tank material may be highly reflective, but I was hoping I didn’t have to insulate the entire tank wall (it’s about 5m deep). Is there something else I can try to optimize S/N ?
I will be posting this question on the Waterlinked forum as well.

Hi Bart

Interesting challenge. We will work with you to solve the problem.

We have contacted you on e-mail for further follow up.

Best regards
Johannes / Water Linked

Was there ever a solution to this? My team is having the same problem with a steel tank that is 3m x 2m x 1.5m. Thanks!

I asked Johannes here the same thing just this week, here’s what I got:

They’re still working on the software update for it, but in the meantime they found a workaround.
They generate small air bubbles by running a water pump for a couple of minutes to generate enough absorption to make the positioning work.
I haven’t had time to test this myself yet, but I will soon.

Hope it helps!