Fiber for underwater applications

Apr 07, 2005 4 Replies

Rate this thread:

Piotr Trela 21 years ago

I am looking for ways to send a digital signal from an underwater (depth up to 250 m) high-resolution videocamera to the surface. I was told that the Ethenet copper wire (Cat5e) would go only about 75 metres, so a "fiber optic IP cable" was suggested. I think I would need the cable, a tranceiver (?) from copper to fibre on one end, and from fiber back to copper on the other end.

I have a few questions:

- would I need any repeaters to strengthen the signal over say 250-300m of the cable length?

- how physically resilient is the cable - can it withstand repeated rolling in and off a winch and immersion in water

- is some kind of armoured cable a solution?

- where would be a good place to look for quotes (I have had problems with getting straight answer so far).

Thanks

Piotr Trela

Vote

AES 21 years ago

Do a Google search on some combination of

underwater hawaii fiber observatory

and then maybe get in touch with them.

(A wonderful example of science, fiber optics, and unexplored frontiers.)

Vote

Scott Studier 21 years ago

Piotr,

2km length on multimode cable. Much further than the 100 meters for copper. Fiber is quite sensitive to bending...you cannot exceed its bend radius without eventually having problems. You would have to take this into consideration.

There is armoured cable you can use.

You won't need a signal booster. Fiber is best installed and not moved.

Scott

Vote

danek 21 years ago

As long as you have the right armoring spooling and unspooling shouldn't be a problem as long as you go slow and the spool is larger than the bend radius of the armored fiber. Fiber has high tensile strength but poor shear strength. I would suggest getting two cables in case of a fiber break. You won't be able to easily repair the armored underwater stuff.

I haven't ordered fiber since the telecon crash so I don't know who is still in business but here is a site that I found when I googled "fiber optic cable armored underwater":

formatting link

Looks like it might fit the bill.

There are lots of e-o/o-e cards on the market. The trouble you will have is packaging the underwater end of the business.

Good luck, P. Danek

Scott Studier wrote:

Vote

Ned Forrester 21 years ago

Lots of underwater applications use fiber optic cable. With single mode, you can easily go 10-100km without a repeater (not sure where the limit is within that range). Perhaps for your distance you could get by with multi-mode. You might look at these two companies, amongst others:

formatting link

I'm sure there are others. What others have said about bending is certainly true, each cable has its own spec for bend radius and load.

More than the spooling problems, your biggest problem may be fatigue life of the cable at the ocean surface. I guess that would depend on how much time the cable would spend on the surface in your application.

If you need a multi- or single-mode slip-ring, the vendor that we use is:

formatting link

Vote

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required