This is my first post on this forum. ROV is something i was thinking about since years and now i decided to go into it. I’m after reading tons of topics on all ROV related forums on the web and have built some knowledge base.
I divided my concerns about ROV into the following blocks:
- frame type, number of thrusters/DOFs
- materials for the frame: HDPE, alu, PVC pipes, acrylic
- thrusters type
- control system
- communication and tether type and this point i’d like to discuss here guys.
- power choise - i will use onboard battery packs.
Note my main assumptions are: cost effective, diy made parts, 100m - 150m water depths operation, tether lenghts up to 250m, video stream 1080p.
As for onboard ROV control system i’m thinking about PixHawk autopilot platform + Raspberry Pi3 + 1080p usb H.264 camera or Raspberry Pi ribbon cable camera. You may know this type of control system from ArduSub.com or bluerobotics. Yes, the idea came from those sites.
The only part of the system i do not like is the Fathom-X ethernet-twisted pair modules. It is too pricey for me at USD 159 plus shipping to Europe, VAT and customs:/
I see lot of you guys use ethernet Cat5 cables. Is it really necessary to use some kind of amplifier between onboard ROV Raspberry Pi3 ethernet connector and surface? I’m aiming at 250 meters of cable. Would it be good for 1080p video stream, telemetry and control?
Second idea is fiber optics - single fiber cable. I saw many ROV builders was talking about some sort of video-to-fiber converters + data channel (RS-485). But Why can’t we use standars fiber optics iethernet routers like this one:
It use one fibre for two way transmission: 1550 nm wavelenght on TX and 1310 nm on RX. On the other side on the tether MC112CS should be used. According to specs 20km long hi speed transmission can be established this way.
So it can looks like this:
PixHawk+Raspberry Pi3 <-> TP-Link MC112CS <-> fiber optics tether <-> TP-Link MC111CS <-> PC/Tablet/RaspberryPi3 (i wonder if QGroundControl platform can be installed on Raspberry Pi3 ???).
Note MC112CS max power consumption is 2,5 W (according to scpes) wchich is nice for onboard powered ROVs.
What you think about such system?