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ROV Communications?

A project log for Sphere ROV: 8BitRobots

A novel underwater spherical robot powered by the 8BitRobots module

Tim WilkinsonTim Wilkinson 06/20/2018 at 16:258 Comments

I'm still considering various communication options for the ROV. Here are my current thoughts:

My previous ROV has taken the Powerline approach, but before simply taking this route I want to explore all the options. I'd be interested in any feedback.

Discussions

K.C. Lee wrote 06/21/2018 at 01:26 point

There is always 10Base2 - old 10Mbps over 50 ohms coax.

https://en.wikipedia.org/wiki/10BASE2

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Tim Wilkinson wrote 06/21/2018 at 04:54 point

Oh that takes me back to my college days. I wonder if USB versions of this stuff even exists.

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K.C. Lee wrote 06/21/2018 at 10:38 point

There are some old stocks of 10BaseT to 10Base2 bricks.  It is an obsoleted standard afterall. 

There are 2-pair stranded cat5/cat5e which is all you need for up to100Mbps.  They would be more flexible than regular 4-pair ones, but harder to find.  Belden has some industrial products.

https://www.belden.com/products/industrial/cable/ethernet/cat5e

Serial over EIA/TIA 422, EIA/TIA 485 if you don't want to work with Ethernet.

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K.C. Lee wrote 06/21/2018 at 01:23 point

USB as is I think is limited to 5 meters or so.  Last time I look into it was about latency, so it is not a simply way of fixing that with a passive device.  You could have a strings of hubs every 5 meters, but that get tedious. 

http://www.yourcablestore.com/USB-Cable-Length-Limitations-And-How-To-Break-Them_ep_42-1.html#maxactive

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Tim Wilkinson wrote 06/21/2018 at 01:35 point

Well there is Corning's USB over fiber which will do 100ft ... but it's a bit pricy so I've been ignoring that unless I find a cheaper version. https://www.corning.com/optical-cables-by-corning/worldwide/en/products/usb-optical-cables.html

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Tim Wilkinson wrote 06/21/2018 at 04:56 point

Thinking about this, I have to say it's tempting. I'd need to find some sort of external USB underwater docking enclosure because I don't really want to epoxy a $200+ cable to the ROV.

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Tim Wilkinson wrote 06/21/2018 at 00:53 point

Thanks. I'm going to take a look at the POF stuff. Hadn't heard of that.

The LX200V20 module is the same one I list although the reference I gave includes the extra board to make it easy to plug into ethernet.

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Francisco R. Pereira wrote 06/20/2018 at 23:41 point

About the communication, have you considered using pof (plastic optic fiber)?

I was looking into this: http://www.instructables.com/id/Building-POF-home-user-network/

I'm thinking about the possibility of building a small ethernet adapter for the pi zero using this transceiver: https://store.fiberfin.com/index.php/products/active-components/optolock/650-nm-fo-transceiver-125-mbps-industrial-ethernet-with-optolockr-2-2-mm-pof-lvpecl-i-o.html

For the powerline I found also this module: https://aliexpress.com/item/PLC-power-cat-module-RAK-LX200V20-embedded-power-Line-Communication-module-with-ultra-high-speed-200Mbps/32789800405.html

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