Home        Store        Docs        Blog

Fathom-x link speed

hi, i’m trying to get 2 fathom-x boards communicating at the expected speeds of approx 80Mb.

i have 2 new boards along with 200m of BlueRobotics 2-core cable.
using iperf i’m getting the following results:

Client connecting to, TCP port 5001
TCP window size: 85.0 KByte (default)

[ 3] local port 56002 connected with port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.6 sec 1.50 MBytes 1.19 Mbits/sec

terrible network performance, please could you advise, on how to up this to 80Mb?
without the fathom-x, i am achieving 300Mbits+ (using a pi3b+).

i have also tried connecting the 2 fathom-x boards with a piece of twisted pair cable on my desk - same approx 1Mb max rate.


on further investigation i have been able to verify approx 50-60mb link through the fathomx. I hadn’t realised the gstreamer video was still running when I ran the last test.

so link speed is ok, the symptomatic laggy video is a different topic!

Hi @ablopablo,

What length of cable are you currently using to test? The speed drops over longer lengths, so 50-60 Mbps could be expected over some cable lengths.


we’re using the 200m reel from BR.
i reran the iperf test with all video streaming stopped &achieved the 50-60mb. i can live with that speed, but am struggling to get the video feed to be acceptable.
the low light HD camera works a treat with a direct connection, but through the fathom &200m reel, it stutters and updates every 5secs or so.

the original iperf data was with video streaming running.

Okay, that sounds like a normal speed for 200m length. Can you try with a shorter length of wire between the Fathom-X boards? If that fixes it then the tether length is likely the issue. If not, then there might be something wrong with one of the Fathom-X boards causing packet loss.

thanks for the help so far,
i have done that test, getting similar speeds, I.e. approx 60mbps (using iperf).
used a length about 20cm twisted pair.
should the speed be better than that?


We usually see closer to 80-90 mbps over short cable lengths. That’s assuming the video isn’t running. If you think something is wrong with one of the Fathom-X boards, send us an email at support@bluerobotics.com and we can sort it out.