I am working on a hobby project where I am trying to build a ROV (Remotely Operated Vehicle) for underwater use. The ROV will have some electronic parts, that are powered with 12v and 5v, that I have not selected yet. (Brushless DC motors, servos, LED lights, video camera, microcontroller,...)
For mobility I am concidering to use one or more 12v batteries (car bat. or lead bat.) on land and a laptop with an microcontroller for controll.
So I want to use a cable that has 4 cores, two for power and two for data.
I would like to have at least 100 meters of cable, but a range from 200 to 300 meters or even longer would be much better. Is this possible ?
What cable should I choose (low cost is priority) ? Whats about the voltage loss over distance ? Is it better (and safe) to invert the 12v DC from the battery(s) to AC and transform back into DC at the ROV ? And what would be the best way to design the data transmission ?
The data that comes from my laptop to the ROV will be mainly control signals that a microcontroller at the ROV will interpret. The data that is coming from the ROV back to the laptop, is video and sensor data.
If the data (mainly the video data) transfer would be a problem, I was thinking of only using a cable for power but using rf communication for sensor data, control and live video. I don't want to mess with underwater low frequency transmission (since I think this is way to complicated) so I was thinking of using an antenna that floats on the water surface. (Connected to the ROV over a fixed length cable, that would limit me in operation depth)
I am happy to hear all of your ideas and advises.