Removal of the power supply and communication cable

Hello,

My name is Arthur ENGASSER. I am an 18-year-old French French student in preparatory class in order to become an engineer. As part of my studies I have to deal with a subject related to the ocean, seek information, conduct experiments in order to provide scientific added value on a defined subject. I became interested in underwater acoustic communication. So that's why I'm contacting you. 

As one of the first companies to develop the underwater drone, you are probably the most likely to help me guide my research. 

I would like to learn a little more about the solution you have chosen so that the user can communicate with the drone. I have already understood from your forum that cable is not only used to communicate with the drone but also to power it. However, it seems to me that the cable limits the movements of the drone and therefore the exploration of wrecks for example. So I wonder why you chose to use a cable. If you can provide me with some answers, I would be very grateful.

Thank you for reading this post!

Hi Arthur,

The tether is used for comms and to provide 5V to a opto switch in the ROV, which turns on the power. The tether doesn’t actually power the ROV as there are lithium batteries in the ROV which power the onboard electronics. This also allows the user to reboot the ROV from the surface.

The reason a tether is used instead of acoustic modems is due to bandwidth and cost. It’s difficult to purchase an acoustic modem for under $1000 USD. Something like the blue robotics M64 is $1500 USD and provides just 64bps of bandwidth. That’s enough to send 8 ASCII characters a second. The text in this message would take about 2 minutes to send underwater. The ROV and topside controller would need a modem each so the drone would be 4x the price and could no longer stream video.

Hope this helps.

Regards,
Brendan

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