Has anyone tried using 2 pairs of Fathom-X boards on the same tether (but separate twisted pairs)? I’m trying to do this so that the vehicle and payload each independently talk to their own dry-end computer. I’m experiencing some network issues on the payload side that seem to be exacerbated when the vehicle is also connected to QGC. Has anyone else encountered similar interference issues?
Hi Ben,
This is a great question. We haven’t actually done any testing with two independent sets of Fathom-X in one cable. I would guess that there would be some cross-talk since the pairs aren’t shielded and that would definitely have detrimental effects. If the cross-talk was strong enough, the boards could potentially communicate with each other on a single network.
We’ve done several tests where we attached multiple devices to the same network of Fathom-Xs. They can be connected in parallel so, for instance, you could have two on the ROV (one for ROV and one for payload) and have them connected to the same twisted pair. Then, the board at the surface would be able to access both devices. You could add a network switch or another Fathom-X at the surface to allow another surface computer to connect to the network.
What type of sensor are you using, if you don’t mind me asking? What sort of bandwidth does it use?
-Rusty
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Why not consider using standard Ethernet switches?
Ethernet can be loaded with any amount of signal load.
Hello,
I’ve tried to use 2 pairs of tether, one for the ROV and one for a sonar. The sonar ethernet is plugged on a second FATHOM-X board, which outputs signal to the second pair. On the dry end, also 2 FATHOM-X boards, so 2 ethernet links, one for the ROV, one for the sonar…
I’ve a lot of cross talk between the two pairs. If I unplugged the sonar ethernet link on the dry end, I can still display its image on the PC !!!
But when the 2 ethernet links are plugged, softwares hang… Ping process (on linux) run to 100% …
I’ll try to use only one pair and to connect to each FATHOM-X…
Have You tried using only one network?
By using a network switch both topside and wetside
So, only one Fathom X in each end, only one twisted pair
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I haven’t tried this, but it should work. The FathomX/LAN Switch act like a piece of ethernet cable, the IP scheme for your SONAR can be any unused address.
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Yes, we have found this as well. You can try @Boko suggestion, however we got around this by running sonar and ROV homeplug connections in parallel (so two homeplug boards in the ROV enclosure), sent over a single UTP. You then need a network switch at the surface to connect the topside homeplug board to. We have a BluePrint Oculus 750d and ROV running with no bandwidth issues (max throughput looks to be about 35mbps, well within homeplug specs)…
whoops, I just saw @k-deboer pic, yes, like that.
Thanks for your help, every one!
I went back to one pair, connecting to Fathom X at the ROV Side (one for Bluerov one for sonar), and a third at the surface side (as @k-deboer show in its diagram), it works fine!
The sonar is a Blueview dual head 900 - 2550, and the tether is 100 m long.
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