packet loss with Cyton mounted on head ? [resolved]
Hi,
Before asking, I would like to explain my steps for using OpenBCI and OpenBCI-GUI.
1. Insert USB dongle to my PC's USB 3.0 port.
2. Fixing latency time of USB dongle from 16 to 1.
-> When I re-insert USB Dongle, the latency time always to recovered to 16.
3. Change USB dongle's permission to use all users can approach ("sudo chmod 777 /dev/ttyUSB0")
Issue: When I turned OpenBCI GUI, the packet loss rate was as follows screenshot.
As we see the screenshot, quite a lots of packets were lost.
Funny things were as follows:
1. When I did not wear OpenBCI, the packet lost was clearly 0%.
2. When I put OpenBCI on my head, the packet lost was approximately 15% ~ 99%.
I wonder that my Cyton board is broken or my settings were incorrect.
Comments
Jrseojr, hi.
A common suggestion to reduce packet loss when Cyton is relatively far from the dongle, is to use a usb extension cord, to position the dongle closer to the Cyton. Also the type of table / desk construction may be affecting transmission also; such as metal desks which block radio waves.
One common strategy with the extension cord is to just 'drape' the end of the cord with the dongle, over the edge of a nearby monitor. That puts it at a good distance from the desk which may be blocking signal strength.
William
Hi! @wjcroft
Thanks for answering, I will try based on your advice.
I have another question.
As you see in the screenshot, with some cycles (interval), similar shapes of patterns occurred.
Originally, I thought that these came from an eye blink, but in my test, it generated. (test condition: gazing at a graph without an eye blinking)
I think that it cannot be generated from brain activity.
Would you please share your idea about it?
When did you purchase your Cyton? Did it always work like this? Do these waveforms seem correlated with packet loss? Have you followed tips to reduce radio packet interferences from other nearby sources of Bluetooth, Wifi, transformers, power supply bricks, etc.?
https://docs.openbci.com/Troubleshooting/minimizingNoise/
@jrseojr I would classify what you have shared as "severe packet loss". The large distortions in the TimeSeries widget are likely packet loss events. Please try the suggestions that William has shared to move the Dongle farther away from the computer and closer to the Cyton.
Recently, another user had the Dongle plugged into the computer which was on the floor below a desk. Using a USB extension cable and putting the Dongle above the desk resolved nearly all of the packet loss. Try something like this and share another screenshot showing the TimeSeries and PacketLoss widgets open just like you have done. I would like to see the result to see if we should reach out to official OpenBCI support for a replacement (given it was a recent purchase).
At first glance, this appears to be electromagnetic interference with the radio, as the blips are not entirely cyclical or equidistant.
Hope this helps!
-RW
@wjcroft and @retiutut
Thanks for your giving advice, I think that I solve my issue.
Using an extension USB cable, I moved the USB dongle to be almost closed to Cyton (actually, I attached the USB dongle to the EEG headset with insulating tape).
In that time the issues (high packet loss and abnormal data) rarely showed.
Well... compared to other EEG sensors (Muse Brainband or others) current OpenBCI is too much sensitive to other electronic waves in my view (I have Muse S either for research).
Thanks for giving advice again!
Again, suggesting that you may have other equipment in your area that may interfere the radio link between dongle and Cyton. It should not be necessary to place the dongle within inches of the mainboard. But glad that is working for you. The radio 'channel' used by Cyton & dongle, can be changed by using the GUI. Changing the channel may potentially avoid the source of interference. Expand section 5:
https://docs.openbci.com/GettingStarted/Boards/CytonGS/#5-optional-settings
Great suggestion @wjcroft! I also recommend changing the radio channel. This can be done in the GUI control panel by pressing the "Manual >" button to open up the manual configuration box for Cyton.