Using Micro studio 4K in deep sea housing over ethernet

Hi all, this is my first post in this forum.

I am building a deep tow camera system for work and purchased a Black magic micro studio 4K (for another project) it fits perfectly in my 6000m titanium housing.

I have run into a snag with how to get the 6G-SDI video up to the surface and the SDI control down to the camera.

I have attached a diagram of what i am trying to acheive but I am looking for advice or suggestions on what equipment will acheive this or if it is even possible.
I understand that I probably wont be able to get the 4K to the topside.

My idea was to convert the SDI out via an SDI - ethernet H.265 encoder then into my switch - media converter and up my F/O cable. At the top side decode the ethernet to SDI and record on a Video assist recorder. Im not sure if I will be able to get the SDI control down to the camera via this method.

Thanks in advance for any help or suggestions

Nick

Black magic diagram.JPG (82.11 KiB) Viewed 3417 times

How many FO cables do you have in the tether? Best would be SDI to FO and FO to SDI on each end, but would require 2 more fibers.

If you haven't purchased the fiber cable, I'd probably go with at least 6 fibers. The last time I priced cable the fiber count made very little difference in price between 2 and 12 counts, but might be different in your application.

Can you control the camera from LANC or S-Bus? https://www.skaarhoj.com/products/eth-lanc-link/ https://discuss.ardupilot.org/t/s-bus-o ... rnet/31008

I haven't used either of the above, so not certain it will work. I'd try to get a fiber for SDI to get a higher quality recording and ditch the stream encoder.

Just get the SDI onto fiber with 2 bi-directional fiber converters.

If you need it to go over the existing fiber you can go 2 routes. Or buy BIDI sfp's For the network and for SDI. ( Yes SDI bidi does exist! ) Or go CWDM. Add CWDM converters on both sides and CWDM SFP's.

But what you go fiber instead of streaming. Streaming has latency, and streaming a videofeed back only for camera control is a bit overkill i think.

Get a set of these
https://www.blackmagicdesign.com/produc ... /W-CONM-29

Thank you Greg and Daniel,

We already have our armoured fibre cable. it is a single fibre, single mode unfortunately this was purchased before I started on the project. I have some spare WDM media converters to connect if I get the 12G SDI to fibre converters

My only other question about this set up is, when converting from SDI - Fibre - Ethernet does this work over my IP network with my other IP units connected in?


Thanks again for your help.

Nick

1 fiber only? That is quite strange.. Normally you see 2 or 4 fibers inside..

You put a SDI Fiber converter on both end's And get some cleaver CWDM to get it working.. Because 1 fiber is really limited..

A single fiber is going to be difficult, could it be a single pair of fibers (transmit and receive).

My thoughts would be a rather expensive 40gbe or faster network and some rather expensive sdi to ethernet devices. I'm guessing that in the end new cable might be cheaper, but I may not know about all of the options available. I'm not at all familiar with fibers for long distance under water use, but my first thought would be to contact places like Fiberdyn and see what they suggested. I'm guessing there is power, fiber optic, and some form of cords for strength inside what is probably at least a 2 layer jacket. My next contact would probably be some of the oil companies and see what they are using on their ROV's.

Well it can be done by 1 fiber. But you need to use a bit of a trick..

When buying SFP's and Fiber muxers, need to buy a set that does not match to eachother..

Hard to explain in text. But you then would need to work with normal CWDM sfp's. But run all different frequencies.

The trick is that the receiver path of an SFP is fairly wide and often with CWDM full range.
You can use this in your advantage.

As you can see in the image below. The set of TX CWDM for the first pair is 1470 + 1490 So they are split apart by 20nm. This is not as efficient as a 2 fiber system as you use twice as much frequencies. But it works well.

Hmmm... That's interesting. I haven't used any of those devices before but will now keep it in mind if I get into a difficult situation.

Do you think it would be a problem that the CWDM only seems to be 10gbps per channel vs. the 12gbps of the video feed? The more expensive DWDM offers up to 100gbps per channel. Or do you just find a tool to allow splitting the 12g SDI into two 6g connections and using two of the available 16 channel pairs?

https://en.wikipedia.org/wiki/Wavelengt ... ltiplexing

Still very interesting stuff that I'll need to research a lot more. We have multimode fiber almost everywhere on the campus where I work, it could be useful to know more about this topic and specifically moving video and audio on one or two (normally) dark fibers. Sounds like a good product suggestion for BMD to create.

@Greg, Dont look at the SFP's For 12G video Get 12G CWDM video modules. 10G Data modules will fail at some point because they can not handle the error correction on the long Video data streams. Compared to much smaller data packaging that is used on Network comms.

But i took this picture to point out that with 8 different frequencies you are able to create a 4 channel system trough 1 fiber. Just to help out on the issue to run those 6G video streams up and down, while also have an Ethernet up/down link on the same fiber.

Diving down a rabbit hole, I found this and started reading. Those following along may be interested.
https://community.fs.com/blog/how-to-us ... demux.html

And also since you only need 6g for 4k/uhd at 30fps, you can get by with a single channel.

And BMD does make SDI to fiber (sfp connection) that is bi-directional, so they most be thinking along the same line. But I'll still take you advice and look for the modules that you recommend. We are only HD so this may be way more than I would even need, but still good to learn.