Long distance video transfer over wire / General Science and Electronics / Forums

Forums

4hv.org :: Forums :: General Science and Electronics

« Previous topic | Next topic »

Long distance video transfer over wire

previous 1 2 3 next

Move Thread

LAN_403

Patrick

Sun Jan 06 2019, 12:34AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Maybe design/build/test the vehicle with a fiber optic-steel cable and batteries, then convert over to power from the surface later.

Carbon_Rod

Sun Jan 06 2019, 06:57PM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

Single-fiber multi-mode NICs are around $60 each.
Some use cheap un-shielded acrylic fiber-optic for ROV, and have a surface on disconnect fail-safe mode.

You may find inexpensive tethers that can be handled like fishing-line are often preferable to a heavy umbilical with limited range.

the_anomaly

Sun Jan 06 2019, 07:07PM

Registered Member #19 Joined: Thu Feb 02 2006, 03:19PM
Location: Jacksonville, FL
Posts: 168

Thanks everyone for the suggestions, I think this gives me a good starting point.

The cable is looking like a real pain at the moment. AN hose looks interesting but the low volume cost is high, I've yet to find any spools for sale but I'll keep looking.

I found this cable https://bluerobotics.com/store/cables-connectors/cables/cab-nbpuf-4utp-26awg/. They don't give a max depth or pressure but the price is not so bad and it is designed for ROV use.

If epoxy potting is too rigid, I can fill the center of a tube with epoxy, pull a vacuum to make sure it seals well, and then fill some length with silicone as strain relief.

I am trying to avoid batteries.

The HDMI extender looks interesting, I'm trying to find a more economical approach first but I'll keep that option on the table.

Polyethylene seems to be the material of choice for underwater cables. I'm wondering if it would be more economical to build a PE extruder to make my own cable. I'll research this a bit more.

wrote ...

Single-fiber multi-mode NICs are around $60 each.
Some use cheap un-shielded acrylic fiber-optic for ROV, and have a surface on disconnect fail-safe mode.

You may find inexpensive tethers that can be handled like fishing-line are often preferable to a heavy umbilical with limited range.

Just saw your post before I submitted mine, I'll look into this as well.

This ROV would be used to check on the invasive Lionfish populations at reef sites. I plan to toss it over board, let it travel to the bottom, spend 10-20 minutes under water (50-300') then reel it back up and move on to the next site.

2Spoons

Sun Jan 06 2019, 07:57PM

Registered Member #2939 Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615

If you are going to use polyethylene jacketed cable you will have to look at compression seals again. Nothing sticks to PE.
That cable in your link looks perfect. Strong, flexible, waterproofed, PU jacket ..

Plasma

Sun Jan 06 2019, 09:42PM

Registered Member #61406 Joined: Thu Jan 05 2017, 11:31PM
Location:
Posts: 268

Not directly what you ask for, but what about a electrode at the front and back of the Rob, with highish ac voltage at UHF frequency, it should travel 100 meter's with two electrodes on the boat for receiving.

Leakage current.

2Spoons

Sun Jan 06 2019, 10:02PM

Registered Member #2939 Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615

Not in sea water it wont.

Plasma

Sun Jan 06 2019, 10:21PM

Registered Member #61406 Joined: Thu Jan 05 2017, 11:31PM
Location:
Posts: 268

Not radio waves, but 1.5volt ac can travel 1.5 meters in a bath tub, with the electrodes separated 300 mm ,50mV picked up at the opposite end of the tub.

Why did you say it won't work,could you explain?

DerAlbi

Sun Jan 06 2019, 11:19PM

Registered Member #2906 Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
Posts: 727

The better the conduction, the worse the signal because its better short circuited. Would you argue that the strategy works on a copper plane?

Plasma

Mon Jan 07 2019, 01:50AM

Registered Member #61406 Joined: Thu Jan 05 2017, 11:31PM
Location:
Posts: 268

It would be hard to pick up the signal yes, but volts increase the signal exponential, and space between electrodes distance linearly.

It was just something I though interesting, I suppose back to the OP

the_anomaly

Mon Jan 07 2019, 11:46AM

Registered Member #19 Joined: Thu Feb 02 2006, 03:19PM
Location: Jacksonville, FL
Posts: 168

It might affect the reef fish too much. Years ago I worked with a fish club responsible for river management. When it came time to restock, we went to a distant stream and used electricity to attract the fish into nets. It was amazing to me, the fish swam right to the electrode as though they were possessed.

previous 1 2 3 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob