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URGENT! Communication Problem with different ROV and Tether

Hello Everyone,

We have a problem that we haven’t found a solution for a long time.
We have 3 Bluerov2 and 3 Tether with the spool (300m). (all of these systems completely same.)
Problem is that we can’t use random spool for random Bluerov2.
For example, one of our ROVs can only work one of our Spools or 2 of our spools. When we connected to the different spool, our latency test is coming very low like 0,1 or 0,2 Mbps.
But when we use different ROV with the same spool i can measure more than 60 Mbps.

We tried everything, we checked the troubleshooting steps, we checked the connector’s pins, we changed the Laptop and fathomx board but we could not find anything.

How can the Tether choose the ROV to work?

We would be very glad to solve this issue

Welcome Shapeofwater,

We hope you can get to the bottom of this problem. Have you measured the resistance of each core separately? It might be a broken wire that is intermittently making occasional contact and has high resistance.

The units should work in unison. Confirm that all ROVs and laptops are running the same software updates and each unit is identical in firmware.

Is the tether on a spool? Have you maintained the slip rings? Do you have a test umbilical (2m test piece) available to confirm ROV and interface communicates without the tether?

We are happy to help you and hopefully solve this issue.

Kind regards

Deep Supplies

Thank you for your interest. I m very gratefully.

Yes, all ROV’s updated lastest firmware and software is the same.
Yes, all tethers are on a spool. Slip rings are quite new. (one of them is bluerobotics’s spool)

I will try to make these test you mentioned as soon as possible.

But I still can not understand, If there is any problem on the tether, it should not work with the any ROV.
But I can get more than 50 Mbps with the different one.

Hi Shapeofwater,

Are you able to list the tethers and indicate what components are on each one?

If you have only one Bluerobotics spool, what results do you get on this compared to the other two?

Slip rings should be maintained every 6 months. Maybe inspect for corrosion or damage.

Let us know your findings.

Kind regards

Deep Supplies

It should not matter, but could it be a difference in the connection of + - (blue and white wire) on the fathom-x board?

I’ve had similar problems with the same tether. (300m) Sometime I got 0.5mbps sometimes I got 40mbps. Through the slipring or not and various combo of fathom x or colored pair didn’t solve anything. Grounding the unused pairs didn’t change anything.

I ended chopping it in half.

I now get my own tether custom made with shielded twisted pair and I don’t have this problem anymore.

I have a friend who had two fathom tethers beside each other and plug top side and bottom side using using the end from one and the other by mistake and had comms. That’s how bad the cross talk is.

This may be the reason why this is happening…