February 2, 2018 at 13:56 #2118
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: https://www.youtube.com/watch?time_continue=26&v=doYs5kI83jc . 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 ?February 2, 2018 at 13:56 #2119
Perhaps it’s possible to adjust signal dB strength to get a better S/N? My usage will almost never need the signal strength to cover 100m, maybe 20m maximum.February 2, 2018 at 14:01 #2120
Interesting challenge. We will work with you to solve the problem.
We have contacted you on e-mail for further follow up.
Johannes / Water LinkedMarch 20, 2018 at 17:59 #2308
I am having similar issues. I have been tinkering with my Underwater GPS for about 3 weeks now. I have my receivers installed as per the configuration here:
My tank is 20′ x 16′ x 4.5′. It is highly reflective. I would like to know if we can get better S/N ratio than what I typically get. The following is kind of the best case scenario thus far:
I would like some tech support on how to maximize position accuracy in the pool (highly reflective) — help with calibration, positioning/orientating of the receivers etc.
Do we have access to the raw signal and the filtered signal from each receiver via the API?
Also, what are your recommendations for pool liners? I do not want to insulate the entire tank because I would like the sonar to “see” the walls. FYI, I am using a multi-beam sonar for SLAM (simultaneous localization and mapping).March 20, 2018 at 18:01 #2309
mchandrasekaranParticipantMarch 21, 2018 at 13:10 #2313
We are aware that some tanks (typically made of steel) may produce so strong acoustic reflexes that the position accuracy will be degraded and as a worst case fall to zero. We are however working on adapting our algorithms to counter for these special environments. Updated algorithms is distributed through free software updates to the Explorer Kit.
In the mean time we suggest that you try to dampen some of the acoustic reflexes. This may be done with pool lining. We have had success with just some cheap artificial turf. You can try to cover a small area first and then see how far you have to go to acheive an acceptable performance of the positioning.
The raw signals from each receiver is not available through the API.
Your receiver setup looks ok. Try to spread them out as much as possible and drop them to different depths as well.
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