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Puzzling communication bandwidth problem


(Richard) #1

Hi All
I’ve been having intermittent trouble communicating with my BR2. I’ve chased down and eliminated a bunch of potential sources and now find myself stumped. The issue is pretty much summed up by this screenshot:
bandwidth%20issues
Sometimes the download speed is just as high as upload, but alot of the time it’s like this, and even when it’s pretty good there are enough momentary drops that QGC will lose video and vehicle heartbeat for a few seconds, which is not confidence-inspiring. I’ve chased down potential physical problems like tether, slip ring, ethernet cables, etc. The Pi seems to be happy, and I’ve disconnected any other devices and removed any other jobs it was doing to be sure it’s OK. Anybody have any ideas?

Here’s a link to what QGC looks like when things are going “better”, as opposed to no video at all:
https://youtu.be/ti937_gt7pQ


(Jacob) #2

What browser are you using? Try chrome.

Also, try iperf3 to get a definitive result. https://gist.github.com/rjehangir/66f84eec293273da5e88eae4fa9514f0


(Rusty) #3

Hi Richard,

The Fathom-X boards use more power when transmitting because they have to drive the signal lines. If you’re always seeing lower download rates than upload rates, you could have a power supply issue to the sending board. In this case I think that would be the topside Fathom-X.

We have recently upgraded the BEC power supply on the ROV to allow more room for expansion and other 5v devices. If you’ve added anything to your 5v lines, I suspect that as well. Here’s a link to the new BEC: https://bluerobotics.com/store/comm-control-power/elec-packages/bec-5v6a-r1/

-Rusty


(Richard) #4

Thanks for the replies, Jacob and Rusty. I will grab one of those new BECs as soon as I can. I have two of the older ones in there now, one for the Pi and one for the Pixhawk rail. My topside Fathom-X is powered by a large USB battery pack capable of 2.4A output, and it’s always seemed to do the job well enough. I will check on it.


(Richard) #5

I think I might have a hardware problem with the onboard Pi-- the lights on its ethernet jack keep going out entirely, coming back on randomly, I think I caught the Pi rebooting once when I couldn’t communicate with it… I have a spare so I’m going to swap it in with a fresh disk image and see how that goes.


(Rusty) #6

Hi Richard,

Okay, that sounds like it could be the BEC power supply to the Pi. If you’ve had anything else attached to the 5v rail in the past then the BEC might have been damaged. They normally supply just enough power for their default function and not much more. The new BEC has plenty of excess.

-Rusty