600m tether length with advanved bluerov2 package

Hi @corndog,

I’m not sure what answer you are looking for, but the numbers are pretty straightforward:

  • The maximum reliable communications distance over the Fathom tether is 300 m with the Fathom X
  • The maximum reliable communications distance over the Fathom Slim tether is 200 m with the Fathom X

Beyond these lengths, we found our current system becomes unreliable, with bandwidth going off a cliff, communications constantly going in and out, and packets dropping. The difference between working fine and not working at all can be as little as a few meters. We believe the difference is down to the specific properties of the cables, inducing resistance, capacitance, inductance, and overall frequency response. This is what Elisa relayed to you from me.

The homeplug communications standard is no easy task to unravel, as it uses a whole swath of frequencies from 2Hz-28mHz. Unfortunately we can’t really give you an “you’re on your own, but…” comment, as we’re still figuring this out ourselves. However, we are working on it and currently taking a deep dive into the standard and nitty-gritty details of how this communication works, moving towards hopefully raising this current limit. If you want to go beyond our existing ratings you are welcome to do so, but you are truly on your own and in the same boat we are currently in.

At this point to only reliable method to significantly extend tether range is to go with fiber or perhaps switch to serial communication with analog video.

-Adam

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