Topside tether configuration



Sorry if this is such a newbie question, but on the topside connection with the homeplug and the controlling computer, is a router necessary to connect the homeplug tether too, as well as the laptop, or do people connect the homeplug directly to the laptop and have the laptop 'Internet connection share' with the Beaglebone?

Having a router seems troublesome in the field, as it needs external power.

But my wonderful little new laptop does not have an Ethernet port (Lenovo Yoga 13 with Windows 8). I could get an RJ45 to USB adapter, does anyone know if this will work, to hook the homeplug up to an RJ45 to USB and connect the Beaglebone to the laptop this way (with no intermediary router to assign ip addresses, etc.)? What methods are people using?

While pondering all of this, I thought if I had a spool that had the homeplug adapter, a 18volt battery, and a wifi to rj45 dongle, one could make a tether spool without a slip ring necessary, just contain all the electronics in the center and let them rotate with the spool as it pays in and out. The battery could send voltage down to the OpenROV, which could then not have need for onboard batteries. (the voltage drop of 18v through 300 foot tether would be to about 12v @ 1amp draw) This is what I found of interest to power from the topside , seems it has enough juice to power the rov and the wifi dongle and topside adapter and is easily recharged.




You're thinking in the right direction. The ROV can be plugged directly into a laptop without going through a router as long as the ethernet port on the laptop is configured to have a static IP in the address range (something like 192.168.254.* where "*" is any number other then 1 since that's the address of the ROV).

There have been a few discussions about just putting a router and battery inside a spool so that the system is independent- I'll try to find some links for you, but certainly the idea is doable. Okay-- I'm off to meet with a physicist about underwater optics, but I'll send you another message when I get back!



Here's a thread on a tether spool that was made using a slip ring.

I think using a router and battery inside the spool would also give you the advantage of not needing to be wired in with your computer. As a third option, we (accidentally) found that two tethers placed very close to each-other can inductively exchange data, so it may also be possible to have your spooled tether arbitrarily terminated, and have the laptop/ router attached to a tether that runs parallel to the one going to the ROV. We need to do some more experimentation with this but it seems that you can get good video and controlability using this method, and it could make slip rings/ internal routers unnecessary even when using a spool for tether management.