fft signal jumps around 50hz - what does this indicate?

khofstadter · July 2019

hello,

my fft signals are jumping up and down around 50hz, somewhat randomly with the wifi shield.

Could there be anything wrong with my wifi-hardware or perhaps how it is connected to the cyton?

Maybe there is an issue in the software that I am not aware of?

With the same EEG cap, cables, the serial communication via bluetooth is not jumping.

Examples of these jumps can be seen in this (rather long) video:

(from 2:14)

I tested this on

Mac OS Sierra 10.12.6

Macbook Pro 2015

OpenBCI_GUI_v4.1.2 and OpenBCI_GUI_v4.1.3-beta.1

Cyton firmware: 3.1.1

Wi-fi firmware: 2.0.5.

Thanks!

k

wjcroft · July 2019

Kris, hi.

Try using UDPx3 instead of TCP. In general UDP is less overhead and performs better than TCP, less load on the ESP microcontroller on the shield.

William

khofstadter · July 2019

Thank William,

UDPx3 was the only one not working at all, see video from 5:38.

I tried with both GUI versions (maybe I should try with an earlier version).

There are two logs in relation to this in my last github issue response

https://github.com/OpenBCI/OpenBCI_GUI/issues/555

under open_bci_log03-1 and

under open_bci_log03-2

Thanks! k

wjcroft · July 2019

Mentioning Daniel @daniellasry and Richard @retiutut. In case they might have any tips on why your UDPx3 is not working.

Has the UDPx3 ever worked for you in any circumstance? Perhaps on another laptop or version of GUI, firmware, etc.

I do see you have the issue open on Github.

https://github.com/OpenBCI/OpenBCI_GUI/issues/555

Probably best to just continue conversations on the issue post.

retiutut · July 2019

Yes, I saw this earlier. Working on a backend issue related to the Bandpass Filter that might be related to what we see in the video, but more time is needed. I haven’t watched the full video yet, but maybe turning off the bandpass filter removed packet loss spikes.

wjcroft · July 2019

Thanks. Seems like UDPx3 would solve any packet loss?

khofstadter · July 2019

thanks. I'll experiment with the filter as well next time.

khofstadter · July 2019

hello,

I did some tests with filters off and then compared the signal with bluetooth signal at the end of the video:

same system as above using OpenBCI_GUI_v4.1.3-beta.1

issues:

1. UDPx3 not connecting;

2. signal is still jumping around 50hz (UDP) even with filters off;

thanks! k

// I updated the GitHub issue as well, perhaps I should only post on one website, correct?

fft signal jumps around 50hz - what does this indicate?

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