Shawn
Shawn
About
- Username
- Shawn
- Location
- Chicago
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- Member
- Location
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Comments
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Hi, I have another question, how could I add markers at some specific time points to the data stream? Or is there another way to create a separate file with marker info and merge it with the data from OpenBCI GUI? Thanks
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@wjcroft said: Correct, already has the single reference location you have chosen. You can re-reference if you want, not needed. Zero reference is a different type of re-reference. https://eeglab.org/tutorials/05_Preprocess/rereferencing.h…
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@wjcroft said: 'Bias' is the same as 'Ground' on other EEG amps. All EEG is 'differential' (subtracted) voltage, measured between the channel in question and the 'reference' / (SRB2 on Cyton) lead. There is no separate reference channel on Cyton.…
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@wjcroft, Hi William, I am using the 10-20 system with a cyton-daisy board. When we collect data, there are both BIAS and Reference channels connected. But does OpenBCI GUI save the BIAS and Reference data? If not, how should I set up a reference ch…
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Hi William, Thank you for your reply, how about the txt files? Since the CSV files don't have headers for each column.
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Okay, Thank you so much.
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Thank you for your timely response, the blue part in this pic is self-printable, right? But I can't find where to get the wire and metal part next to it in the shop.
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Hi William @wjcroft, I am wondering if is there any place I can get more components like the one in the pic (not the comb electrodes)? I would like to make some spare ones to back up my experiments. Thank you!
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@wjcroft You got me there. hahh But last time was just one channel and has been proved it was the worn electrode problem. This time all channels railed with BIAS, they are all 100% new electrodes. It's so hard to believe all new electrodes are ma…
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@wjcroft, thank you for your help. I just found that if I turn off BIAS in the panel, the issue could be fixed. (Please ignore Channel 4 in the pic) The problem is how well could I trust the data without BIAS, and any other steps that need to be do…
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I use these as reference and bias: https://shop.openbci.com/products/earclip-electrode And these electrodes: https://shop.openbci.com/products/eeg-snap-electrodes
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Thanks for the suggestion. I did use my hand to hold one sensor and make sure I put enough pressure on it to my scalp, and I tried multiple times with different areas on my head, didn't work. My Ultracortex is using different types of electrodes (…
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Yes, I have read it. Actually, I have another set of Mark IV headset and electrodes which works correctly. The reason I customize it is because I need it to be compatible with another Hololens device. And I am pretty sure I have enough pressure fo…
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Thank you for your reply, William. I tried with a larger range, as well as "auto", they are still railed. Any other possible reasons? Or any other check I should make? The impedance is good means the electrodes are well functioning, right? I als…
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However, still wonder why the railed channel could work without the BIAS connected if the electrode is worn.
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Sorry, I mean in the picture I posted in my last comment. Anyway, I figured them out, just because of the electrodes! The unbelievable part here is, we have more than 1/3 of spare electrodes malfunctioned. And the most coincident part is there is …
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@wjcroft said: A common test of EEG channels, is to simply using paste or alligator clips, to connect all three wires / pins together: channel, SRB2 and Bias. This will result in 0uV if the channel is working correctly. Is this what you m…
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Do you have more in detail for this tip:- _Check board function: Connect SRB, BIAS, and railed Channel using jumpers / y-cables / ... This should give you roughly 0.00 uV. See picture (1)._ Since the picture link does not exist anymore. That c…
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thanks for all these info, I just found that it still railed if I just turn off BIAS for the C3 channel. It can only work when I take off the BIAS earclip or turn BIAS off for all channels. And I found one more channel railed this afternoon. Any t…
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@wjcroft said: I explained how Bias and Ground are combined functions on the ADS1299 / Cyton. Turning off the Bias injection sensing for one channel, will not require any adjustments to your signal processing. Because Bias functions are still…
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Thanks for your replying. We tried impedance testing for all channels and found the C3 channel's N status is ridiculously higher than others (4500 to 20 k΄Ω). Does that mean something? If we turn off BIAS for C3 channel, is there any way to denoi…
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Hi William, Thank you for your comment. We tested this by changing it with some works-fine electrodes but still doesn't work. And this also couldn't explain why it works without the BIAS channel connected. Thanks anyway for your kindly advice.…
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We are using Cyton + Daisy board.