Fibre optic tether

Control Boards, Controllers, Tethers, Ect.
Jaman42
Posts: 94
Joined: Nov 3rd, 2014, 4:19 am

Re: Fibre optic tether

Post by Jaman42 »

A bench top CNC sound like an exciting project, my supplier replied to me a couple of days ago letting me know that they will give a proper response once they come back to work on friday.
Jaman42
Posts: 94
Joined: Nov 3rd, 2014, 4:19 am

Re: Fibre optic tether

Post by Jaman42 »

After a mail conversation back and forth about 40 times they finally agreed on sending me the correct units free of charge. I just got a SMS that I got a package to pick up, exciting, I report back.

Edit: I have tried out the new units and they work perfectly, now I get uncompressed video for the live feed and full duplex rs485 over a simplex single mode fiber, sweet.
MNDeepROV
Posts: 34
Joined: May 12th, 2014, 3:46 am
Location: Minnesota

Re: Fibre optic tether

Post by MNDeepROV »

rovdude, et al.

Thanks everyone for continuing to add info on the media converters and fiber options. Much to be learned as there are so many options out there.

And thanks especially to rovdude for all the fiber details and BIG UPDATE! Any updates on your progress? Curious to see how it's worked out, especially the polishing of the fiber.

I'm still working on my hull and frame construction, but have to keep plugging away at the internal planning too. I may set everything internally on ethernet as well. Using IP cams can allow for more image and control options without additional servo work, etc., and keep it all in HD. I plan to use 3 cameras (one of which with PTZ control) and the media converter get big after 2 channels. I'm not sure what resolution the media converter can really handle either. I found a RS485 to ethernet converter that I hope will work on my rov-control X3 that I plan to use to connect it to the network. Still doing research on that though to see if it will work...

So, if I get everything set up on ethernet then all I have to do is convert that to fiber. I was going to use an ethernet cable as tether, but it has it's own challenges I am finding out, and I'll be working in pretty cold water so stiffness could be a factor. Any issue with temp changes on your fiber? Are you going to add a strength member to your tether along with the fiber? Perhaps you don't need to? I want to be able to pull my ROV loose if I get it stuck...which I'm sure I'll do!...or latch on to heavier items and pull them up.
fryslan76
Posts: 290
Joined: Dec 18th, 2012, 4:52 pm
Location: Netherlands

Re: Fibre optic tether

Post by fryslan76 »

Being sick gave me some free time to play araound with my old ROV setup which was still in boxes after moving to the new house.
And I was always intrested in fiber optics so I checked the prices of that stuff. Well I was supriced how cheap it has become.

For example this combination seems to be a good one for me.
https://nl.aliexpress.com/item/Popular- ... 6748&tpp=1
with the following cable to connect it:
https://nl.aliexpress.com/item/100M-Out ... Title=true
The last one is a bit expensive in transfer costs, but the cables are nicely priced.
Combinationofthis
Posts: 1
Joined: May 18th, 2016, 6:07 am

Re: Fibre optic tether

Post by Combinationofthis »

Yes fiber optics has become quite affordable. I would not consider using anything else for small observation class ROV.
I have used regular size FO converters on my ROV but I would love to find something as small as the one you linked here but with 1000M bandwidth.
Cable you found will probably sink. So far the best I found is singlemode simplex cable with 1.8mm OD and FC connectors (i think they are most robust).
100 meters of this cable weighs 348g so that gives my cable density of 1.368 g/cm3 (also sinks). I will keep on looking for more affordable neutrally buoyant FO cable.
So far best that I have found is from company called Linden Photonics (I have attached pdf with cable information). This cable seems even too good to be true -> OD only 1.9mm, neutrally buoyant and tensile strength of 250 lb.
They also gave ma a quote:
<500m - 4.16 USD meter.
500m to 1km - 3.12 USD meter.

Blue robotics slim fathom tether is almost the same price when ordering larger quantities (3 USD per meter). OpenROV neutrally buoyant tether costs pretty much the same (4.10 USD per meter).

If I would live in US then I would probably give this cable a try but due to EU import duties I should pay extra 20%.
Attachments
LINDEN-SPE-7036 High-Strength Buoyant 250.pdf
Linden FO cable
(122.54 KiB) Downloaded 352 times
fryslan76
Posts: 290
Joined: Dec 18th, 2012, 4:52 pm
Location: Netherlands

Re: Fibre optic tether

Post by fryslan76 »

There are postal services in the US to where you can mail a package and they will send it to you in Europe. That solves some of the "we don't sent to the EU or charge you big bucks" issues.
I did not calculate for weight ratio of the fiber cables, so thanks for that.
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