Slow Speeds and Low Bandwidth - Fathom X Interface + 100m Tether


I recently purchased 2 Fathom X interface boards, a spool, a 100m tether with 1 twisted pair, and a 100m tether with 4 twisted pairs. Using different combinations of the tethers and connecting computer different computers, I am getting a maximum 4Mbps and am unsure what is going wrong. The interface on the spool was connected for these tests as well.

Both Fathom X interface boards are being powered from USB. Has anyone else seen this issue? Is this the sign of a faulty Fathom X board? Any guidance would be extremely helpful.

Hi @beansand, welcome to the forum :slight_smile:

Sorry to hear you’re having communication issues.

There are multiple possible causes for that, because there are multiple pieces of hardware involved.

  1. The first thing I’d check is whether you happen to have this issue, which is a known problem with some Fathom-X boards.
  2. If that’s not the issue I’d suggest you try bypassing the Fathom-Xs + tether setup with an ethernet cable directly between the onboard Raspberry Pi and your topside computer, to confirm whether it’s something to do with the tether setup, or one of the ends.
  3. If you have an FXTI box at the topside (rather than a bare Fathom-X board) then it may be worth trying to swap out the USB mini to USB A cable, and if possible the ethernet to USB converter in the box as well

Hi Eliot,

Thank you for the response, the problem ended up being issue number 1 that you linked to. I have since been sent new tether interface boards and everything is working as expected!

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