What is the possibilities to run the BlueROV over a fiber optic cable? If I install Gigabit Ethernet to Fiber optic converters in each end and plug the Fathom-X boards into the Ethernet. Will that work?
Any comments or advise is much appreciated 
We don’t know of anyone who has tried a fiber connection, but you are certainly welcome to experiment around with the BlueROV2. You will need to substitute our Fathom-X board for a Fiber to Ethernet converter that will fit in the remaining space inside the BlueROV2. The Raspberry Pi would connect to the converter and would need to be powered from the main power terminal blocks.
The tether would need to enter the vehicle, be potted in either a penetrator or a waterproof connector, and then installed into the fiber converter. A similar converter will need to be used topside. The bulkhead penetration with fiber is probably the riskiest part and you’ll need to understand cutting and crimping fiber connections.
On a technical level, there is no reason why fiber won’t work, the BlueROV2 is all Ethernet based, you’re just changing the tether communications bridge medium. You may have some issues doing the penetrations and finding a converter to fit inside the 4" tube.
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Would the video lag be reduced if run on fiber?
I have a BlueROV running on fibre optics.
Just as Kevin described above. I use a Lancer Penetrator on the 4" enclosure. If you remove the Fathom X and replace with ethernet to fibre converter you can place a small switch right above it in the 4" enclosure.
No additional comms lag at all on the video plus the reconnect time if you drop comms is much faster without the Fathom X board, with a fibre converter its almost an instant connection. I have a 600m tether which allows me to run the BlueROV Pi system at full ~80Mbps bandwidth as well as running sonar, x2 HD IP cameras and 4K IP camera video all on the same network at that length with no lag with the comms. Video lag is still the same due to processing. Using a small switch in the enclosure allows for a lot of expansion on the network.
Using a BiDi SMP Module in the Fibre converter allows dual frequency operation (one for transmit and one for recieve) on a single fibre line, No need for two.
its important that you understand how to terminate a fibre connection and you have the correct terminating equipment and testing gear. Its not a cheap option but it can be done at lower than normal costs if you shop around.
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Hi Matt,
Are you videos good?
Could you tell what are the HD ip cameras you’re using? and which 4K Ip camera?
Hi Matt,
We would like to try something similar. Do you have links or partnumbers for the different items?
Regards from Norway
Hi Guys
I would rather not put specs on the forum here but if your serious about doing this PM me and I can lead you in the right direction.
In my opinion the only reason to go fibre is to have Gig Ethernet ability at long tether lengths. Its a fair bit of money and effort and not worth it if your only going for 100m.
I got my fibre converters through FS.com, they were really good with excellent customer service. I had a ruggedised tether made for me in the US but i can help you get the right tether off a manufacturer in China for much much cheaper if you dont need it to be heavy duty.
PM me with your email address if your interested.
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Wondering what it takes to run Blue ROV2 over fiber instead of twisted pair of copper wires. What components would be required top and bottome side? Would you still use Fathom boards or be able to plug direct into Pi Computer?
Would running over fiber would the video latency of approximately 200 msecs be reduced?
Would running over fiber would the video latency of approximately 200 msecs be reduced?
No, there is 100-200ms latency even with the camera plugged into the same computer running QGC. A significant fraction of this is probably built into the camera hardware. The network latency is usually less than 10ms latency, even with a copper tether.
Hi Doug,
I already got this done.
PM me if you are interested.
You basically put my module in place of the Fathom board.
This is my fiber optic module installed on my network upgrade:
You can alternatively just install it in where the Fathom-X board is located.
Cheers,
E.
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Hi Doug,
the IP camera needs time to capture the video and “transform it” to a H.264 video stream. This is where the 200ms comes from. I am sure technology will catch up eventually but at present this is what we have to work with.
Any particular reason why this is bothering you. It is hardly noticeable when flying…
What the Fiber Optic mod does is give you as much bandwidth as the ROV possibly can, as if it was connected directly to the ROV regardless of how far it is.
This might sound like it is of no importance but it is actually one of the most important thing if you want to maintain performances with tether length.
This is the bench test I just did with my fiber mod over 300m tether to show you this:
Note the Upload and Download speed.
If I plug a 1 meter fiber lead I get the same results… If I plug an ethernet cable from my computer directly to the Raspberry Pie I get the same results.
Now try this with a Fathom-X. The longer the cable, the less bandwidth you will get.
This not only considerably limits the number of camera / sensors you can use but can also affect the performance of a basic BR2.
In fact, the last system I sold with the latest Bluerobotics mods had very poor performance over 300m tether with Fathom-X.
I had around 12 MPS upload and even less download. Although I did not have the unit long enough to see how I could improve this, it proves the Fiber upgrade to be most valuable in a commercial application.
Brand new ROV and the video had a tendency to lag a lot more than 200ms…
Cheers,
E.
I’m looking to upgrade my BlueRov tether as I’m looking to add a few more sensors. I definitely think for my particular application fiber optic would be unnecessary. Can anyone here share their experience with upgrading the tether to be able to push more data up to the surface? Are there any products comparable to the tether sold by blue robotics that just allow for more data transfer (neutral buoyancy, load bearing, etc)?
What sensors are you looking to add? How long is your tether? If you can get away with a short tether you could set your unit up with a full ethernet system (as opposed to homeplug) and get gigabit speeds (though I think the Pi 3B is limited to 100mbps without doing some mods), but the theoretical max tether length would be 100m, practically maybe less (?)
We’ve run an ROV and multibeam sonar over 300m of cable using the standard homeplug (Fathom) system. I think any bottleneck is likely to be on the tether side (ie whether you use copper or fiber) as opposed to the transmission method you use. For example, the maximum throughput we see using the ROV and multibeam is 40mbps (well within homeplug specs).
Depending on what you are adding, you may be able to get away with the copper tether. In terms of upgrading the tether, I think the only meaningful improvement would be in opting for fiber. You might get small gains from adding shielding, use Cat6 cabling, “maybe” doubling up twisted pairs, maybe even try to use a coax cable, but these gains are probably fairly negligible.
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Jake
As Marcus has said, it depends what your planning to add on.
End of the day it comes down to bandwidth. If your thinking of adding 4K or multiple cameras in addition to sonars etc then your likely going to exceed your copper bandwidth limit but this will depend on the copper tether length. If this is the case then moving to Fibre is a logical step. The benefit of moving to fibre is not only bandwidth and network speed improvements but the ability to work with significantly longer tether lengths and much smaller tether ODs.
Moving to Fibre is quite the investment if you want to do it properly, you have to consider things like your quality of tether brought (you get what you pay for), layout of additional components, subsea connectors, topside connectors, slips ring / reel setups, termination tooling, the knowledge to work with fibre faults and repairs in the field, just to name the major points. If you have experience working with fibre then you already have a big head start. If not, its a steep learning curve.
In terms of tethers there are virtually all options available for a price, you can get very small tethers, very strong tethers, tethers in huge lengths, multi core tethers, hybrid copper / fibres, the skys the limit … as long as your wanting to pay for it. In terms of budget tethers there is a company in China i could suggest who make them fairly cheap compared to the rest, but I would not rely on the quality. Using a glass core is never a good idea for small ROV tethers, once you get a crack its all over. Opt for polymer cores which can recover from severe kinks if you can afford it.
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Hi Jake,
I think the guys pretty much covered it.
I personally have completely crossed over to fiber since I was having loads of issues with only 300m.
I now run on 450m fiber and its like the ROV is plugged right beside the computer. I could put up to 20km according to specs.
I sell these upgrades and tether and its not that expensive really. Tether is just slightly more expensive than the Fathom-X and it can take some serious punishment.
I would say, you need to budget about 20USD of connectors to practice getting good at doing fiber ends and then you are good to go.
Since there are not that many joints, I do not even bother to polish them.
Cheers,
E.
…fiber is fast, but a little to much of an angle and your fiber is gone… my thether got caugt in a little “corner” and it had a twist… suddenly i had 100m Argus tether less(thnx to a diver that didnt pay attention), termination set (1500 dollars)…if you are smart stay away from Fiber… (we use fiber offshore bec we have 4000m unbillical additional to the 300m tether… check prices for the equipment you need too…its Alll expensive… makes life easy without fiber if you ask me 
…but what tether do you need?..all can be made…im planning on a Tether with 2 powerlines and 2 twisted paris and ethernet trough Powerlines…will see how it does;)…price will be nice:)… but Fiber i will stay away from… they brake Easy!
If you want depth, there’s just no other choice. You can’t bend it like wire, but it’s still fairly robust, especially if it’s armored. Hotmelts are cheap and easy and you can hand polish if you wanted to keep cost down. The expensive part is the tether. Fiber to ethernet converters with sfp modules can be had as low as $100 for the pair. A quick disconnect could be a little tricky, but you can always just pot it for $8.
You can also consider VDSL2 if you consider it a bit of a hybrid or a mid way step prior to fibre it won’t have the length or data throughput as fibre but uses basically the same tether and connections as the existing BlueROV and “similar” concept as the existing Fathom-X where it is still just an Ethernet over power connection but as a minimum 100 Mbit/s at 500 m and 50 Mbit/s at 1,000 m
Swap out the Homeplugs for something like a Ethernet Extender Kit
You’d have to test it out, but it’d probably have some of the same issues as with the homeplug module, which is supposed to twice what we’re able to get with the fathom tether. It’s probably better than the homeplug, but there’s no way it’s hitting anywhere near the advertised numbers with BR tether.
I’d say that I’m happy with a tether in the 100-300 meter range. I currently have an imaging sonar and am looking to add a second. That brings the total sensor package to 1 camera (stock camera provided by blue robotics), 2 imaging sonars, an IMU and DVL. The reason for the upgrade is with only 1 imaging sonar we are right on the edge of real-time data flow, a second could definitely slow things down significantly.
Are there any drop in replacements for the fathom board? Are there any good copper tethers out there that have more data transfer capability?
I appreciate everyone’s input!