Transmitting Ethernet over 500m underwater

[Moonwalker031]

Hi I am an electronics engineer and just subscribed to this forum. Its very informative - keep it up.

I have a project for building an ROV. Maximum depth is around 400m but I'm planning to use a cable of 500m for drag compenstion. My idea is to use IP camera on the ROV and send the commands via another IP. Now the problem is how to send the ethernet signal over 500m of cable.

Cat5 is not possible for such lengths I guess.
Fibre optic is ok but expensive and not very flexible.
So I think Coax should be my choice.

Well I found ethernet to coax converters which should work well with RG6 cable but I was hoping to use RG174 so that it would have the least drag possible underwater.
So has anyone worked with ethernet to coax converters using RG174? Or is there some other solution for sending ethernet using thin wire?

 

[Moonwalker031]

Any help or this section is not being used?

 

[robertjo24]

Look into tactical fiber. Small, very flexible, light, and not too expensive.

Patton makes ethernet converters that work well over long distance on copper.

 

[robertjo24]

Here:

http://www.patton.com/products/pe_products.asp?category=387

This will allow up to 50Mbit over long distance copper.

http://catalog2.corning.com/Corning...)&pid=Tactical Cable - EN(CcsNaftaPdfCatalog)

This fiber is very tough and flexible, and not too expensive.

 

[Moonwalker031]

Thanks m8 this really helps.
I am still looking for a solution with a cable of possibly less than 3mm thick.
So do you know if the Patton converter works over RG174 cable 500m long? Or do you have some link for a twisted pair cable with the above thickness?

The fibre optic you suggested is interesting but the outer diameter for 2 fibres is almost 6mm which is too much for me. I found plastic fibre optic cable at 2.2x4.4mm but am not sure if it can withstand 50bars of pressure.

I still would like to use just a single cable though. Do you know if there are Cat5 to plastic fibre optic converters that work with a single fibre for 2 ways commms?

 

[robertjo24]

Is it the intent to have this copper or fiber as part of an umbilical, or is it going to be "the" umbilical?

Will this cable be in direct contact with the water?

I do not know of any CAT5 converters that work with plastic fiber. I do know there are fiber converters that work on singe strands of fiber, but cannot think of them off the top of my head. Try Black Box and Omnitron Systems for starters.

As for small diameter single or dual fiber, I would call general cable and Corning Cable Systems and discuss your application with one of their engineers. I cannot imagine it has not been done before. I know Corning makes a special fiber where the glass is coated for sub-sea applications. Not sure what type of jacketing is available on it though.

 

[andrekakkar]

Hi Moonwalker031!

I found one another website

http://wireguys.ca

on the internet that provides network cabling, voice cabling, Cat Cable, High speed cable etc. Hope it might help people

 

[48as52]

As for small diameter single or dual fiber, I would call general cable and Corning Cable Systems and discuss your application with one of their engineers.

Eng Tips Rocks

thanks,
kk

http://cubuilt.com