Interfacing BCI2000 with g.USBamps

This forum deals with BCI2000 configuration issues.
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feralaes
Posts: 4
Joined: 02 Mar 2006, 14:33

Interfacing BCI2000 with g.USBamps

Post by feralaes » 06 Mar 2006, 11:49

Im on it now!

We just received 4 g.USBamps, im having difficulties communicating these amplifiers with BCI2000. Could you please tell me or send me some hints or clues to establish a correct comunication with the amps and the software, as well as telling me what you know about acquiring 64 channels and show them at the same time.

Another issue is that I have been taking eeg´s and i hevanet been able to save them. I enabled the saving mode but still any data is stored in the carpet with the patient´s name.

thanks,

fer

gschalk
Posts: 615
Joined: 28 Jan 2003, 12:37

g.USBamp ...

Post by gschalk » 06 Mar 2006, 16:26

Hi,

In order to use the g.USBamp(s) with BCI2000, you need to use the gUSBamp.exe source module, in conjunction with an appropriate signal processing and application module, e.g., the ARSignalProcessing and D2Box modules.

Using these modules and the BCI2000 documentation for the USBamps, you should be able to get the amps running. I would start with connecting just one amp at first. When you get this one working, I would add the 3 remaining ones.

Also, have you installed the driver for the USBamps? Does Guger's test program work?

Let me know.

Gerv

feralaes
Posts: 4
Joined: 02 Mar 2006, 14:33

Post by feralaes » 07 Mar 2006, 10:40

Hi Gerv,

Ive installed de amps' driver. Im working with the P3SignalPRocessing as well as with the P3Speller. I made a probe just with 4 channels with the parameters that are said in the BCI2000 documentation for the amps but on the source display, all 16 channels display signals but im almost sure is noise.

Is there something i can do to make a test if the BCI2000 is receiving an appropiate eeg signals just for the 4 channels?

im not sure what is Guger's test

thanks Gerv!

gschalk
Posts: 615
Joined: 28 Jan 2003, 12:37

Re: g.USBamp ...

Post by gschalk » 08 Mar 2006, 03:21

Hi,

If you have set the parameter SoftwareCh (in Source) to 4, then you should only get 4 channels. If the software does not give you a warning/error, then chances are good that BCI2000 is actually getting data from the amp. To make sure, you will have to use a function generator, i.e., any source of voltage between +-250mV that you connect to the amp. I would get a function generator and then set it to, say, a 10 Hz sine wave at 50mV. You should see this sine wave on the source display.

When you successfully acquire data from one amp, you can then try to set the system up for more amps. As I mentioned, the USBamp documentation that comes with BCI2000 has details.

The Gerv

feralaes
Posts: 4
Joined: 02 Mar 2006, 14:33

Post by feralaes » 08 Mar 2006, 14:11

Jo Gerv,

I began transmitting just 4 channels, 1-4.

I was able to put in and displayed the sinewave, the thing is that im only putting it on channel no.1, and it is displayed on channels 2, 3 n 4. What is displayed on ch 1 is a square signal much more bigger than the sine. Dont know why is happenin' if the signal goes in through 1 channel. Do u know what it could be?

Im using the prms that u wrote on the P300 tutorial, just changing the sample rate with a 256. This is because the amps have specific sr's for the filters to work.

thanks men,

fer

gschalk
Posts: 615
Joined: 28 Jan 2003, 12:37

Re: g.USBamp ...

Post by gschalk » 10 Mar 2006, 05:43

Hi,

What is probably going on is that you are using a sine wave that is larger than the +-250mV that the amp can handle. This is why you seem to be getting a rectangle - it's simply that the amp saturates at 250mV. The reason why you get sine waves on the other three channels is that you probably have not grounded these other channels and so the signal from channel 1 is 'bleeding' into the other channels. This is normal.

I strongly suggest to get advice from somebody with electrical engineering experience to get an appropriate connection and setup from the EEG electrodes to the amplifier.

Gerv

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