Next tether?


#1

Last weekend when “flying” OpenROV 241 in my neighbor’s pond my tether was a limiting factor. It kept getting stuck on the plants in the bottom of the pond. I am ready to try something new. Currently I am using CAT5E gray cable, 24 AWG and have 150 ft. on the reel. I am using 4 wires for full duplex Ethernet (not using the single twisted pair adapters) and 1 pair of the remaining 2 pair for extra power for the batteries.

The problems with the current wire is it stiff in cold weather (which we have a lot), it is gray (cannot see it), and it does not float (gets tangled up with stuff on bottom). The good news is it works and I don’t lose the connection with the laptop and can be used to pull the unit back if there is a problem.

Looking over the discussion I don’t see the solution listed. So what is the best choice for the next tether to try? I am willing to buy some and try it in a lake or pond.

John

1500-tetherandtakeupreel.jpg (121 KB)

#2

It looks like this is the next logical step. Essentially you can get full duplex at ~180Mbps using pretty much any two wires (down to 30 gauge, if I read the thread correctly), and the adapters themselves only cost $40. If you still want to have additional power to the rov, you can run it through those two wires too! From what I've read, the higher your voltage the more power you can get from thinner wires, so something like a 12v DC to 120v AC converter, rectified to 150v would get you loads of power through a pretty thin line.

To address your problems with stiffness and visibility, a brightly colored line would work wonders (perhaps intertwine two wires with orange fly-fishing line?) and the thinner your wires, the less stiff they'll get in the cold.


#3

Now I must say I like that Tether spool and the tool you use to get it around :) I need one of those but I don't think my wife will go along with that.


#4

the love of my life, my wife, uses it more than I do. I get a kick out of seeing her drive around when working in her gardens. I did think I bought it for me, but soon learned that I was wrong.


#5

John,

I agree with SpringHalo- the Medialink Homeplug adapters work great, and because the tether can be much thinner, it will be more flexible and won't require as much flotation if you want to make it neutrally or positively buoyant. If you go this rout, make sure you get the right adapter (MHP-EA200X2) as all the other ones we've tried have the power and communication circuitry on one board which is no good.

Here's a link to where you can buy one on Amazon.

I'm interested in the idea of using fly-fishing line in parallel with the tether to make it more buoyant however in my research that line can be quite expensive, and is often fairly short. I might recommend using strands Polypropylene rope in parallel with the tether, or clipping on some other sort of float periodically. I've been thinking a lot about how to easily add flotation to tether in a streamline way, so I'll let you know if I come up with anything too.

Good luck!

Eric

P.S. I LOVE your tether reel system!