Dual Fathom-X Tether Interface Board vs. RJ45 to Binder 770 Bulkhead

Blue Robotics Products Tether Interfaces
1

Good Afternoon all,

I am working on my engineering capstone project and I was looking for some advice around communication between a groundstation PC and a sub. We are designing the sub from scratch, but we have sourced a few things from BlueRobotics. We already have access to a Fathom-X tether Interface from a previous capstone project, but did not realize that the FTXI needs another board on the sub to establish a link.

We have already purchased a 25m, standard type Fathom ROV tether and we are looking to communicate between a groundstation PC and an onboard NVIDIA jetson using Ethernet. We’re hoping to use Ethernet to simplify the communication between ROS2 nodes.

Ultimately, what I am wondering is if anyone has tried going from the Binder 770 connector straight into an RJ45 connector? Is there any problems with transfer speed/reliability if we do this?

Thanks!

2

Hi @nshaw -
Welcome to the forums!
While Fathom tether does not meet CAT5/6 specifications, short lengths up to 30m may work ok to carry normal Ethernet signals. Beyond that distance a tether communications module is required (on both ends as you’ve determined.)

Make sure to use the correct twisted pairs when connecting the rx/tx +/- wires! You’ll need to connect the wires in the vehicle and the topside correctly to an rj45 jack and into your Jetson. Removing the binder connector on the topside is your best bet- as for the subsea side you may need to make a rj45 to header pins adapter so you can just plug into the pairs coming from the wetlink penetrator gland in your housing.