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Author Topic: Noisy Response of EEG-SMT  (Read 3370 times)

casesunny

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Noisy Response of EEG-SMT
« on: December 10, 2013, 03:15:24 AM »
Hi there,

I have tried my EEG-SMT following the procedures, but got noisy signal.
Even there is no electrode plugged in----No DRL electrode or CH1 CH2, there is still a noisy signal.
Could someone help me take a look?

http://postimg.org/image/pn2fm00kj/

casesunny

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Re: Noisy Response of EEG-SMT
« Reply #1 on: December 10, 2013, 03:21:01 AM »
When I plug in ONLY DRL, NO CH1 or CH2, the signal still seems not reasonable.

LubOlimex

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Re: Noisy Response of EEG-SMT
« Reply #2 on: December 10, 2013, 08:53:36 AM »
Hey casesunny,

The pictures indicate improper readings, as you suggested.

What happens if you swap the electrodes of channel 1 and 2? Do you hold the passive DRL electrode firmly in your hand (so it makes good contact with the skin)?

Where are the electrodes attached to? Can you test with just one channel and attach the 2 electrodes above your temples?

Best regards,
Lub/OLIMEX
Technical support and documentation manager at Olimex

casesunny

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Re: Noisy Response of EEG-SMT
« Reply #3 on: December 11, 2013, 04:27:29 PM »
Hi Lub,

Thank you for your kind reply.
I swap CH1 and CH2. The figures are shown in the link.

First, there is no electrodes plugged in, the noise response still exists.
http://postimg.org/image/oya0pvgsn/

Then I place the CH1+ and - on the chest and swap CH1, there is still no signal.
http://postimg.org/image/b0l69hhc3/

Next, I tried CH2. It works well!   
http://postimg.org/image/4xzrdroqr/

After this, I tried CH1 again and it still works! So I guess it has been solved?
My understand is that the system needs settling time for about 15s, right?

One more question, which software can record the data for about 10 min? Thank you in advance!!


LubOlimex

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Re: Noisy Response of EEG-SMT
« Reply #4 on: December 12, 2013, 09:54:10 AM »
Hello casesunny,

The first two pictures look really bad. The last picture looks like a good read.

Quote
My understand is that the system needs settling time for about 15s, right?

Exactly. Since the algorithm calculates medium of the potentials at the two electrodes it needs some data initially to generate valid data.

Quote
One more question, which software can record the data for about 10 min?

Unfortunately, I haven't recorded for that long, so I can't give you proper advice or suggestion.

Best regards,
Lub/OLIMEX
Technical support and documentation manager at Olimex

casesunny

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Re: Noisy Response of EEG-SMT
« Reply #5 on: December 12, 2013, 03:38:38 PM »
Hi Lub,

Thank you for your promp reply!

Is there any software that can write the data, like 1 minute, to a file?  Thank you in advance!

ekinox777

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Re: Noisy Response of EEG-SMT
« Reply #6 on: December 13, 2013, 03:33:07 PM »
Hi casesunny,

Quote
Is there any software that can write the data, like 1 minute, to a file?  Thank you in advance!

OpenVibe is able to do this. It has modules for writing to file for as long as you need and reading from file, so you can review the session and process the signal "post factum".
About others I don't know.