BioBench

[glee10]

hi,

   i am working on a project based on biofeedback where we are analysing EEG signals and giving a feedback to the brain through flickering of lights to reduce stress. i have samples of EEG waveforms of few people. now i have to develop this system in labview. i have to amplify these EEG signals and then i am filtering the alpha frequency range. after filteringi have to follow the algorithm given below:

i)            A .25 second interval of data is analyzed

(ii)         Maximum and Minimum values are determined

(iii)    .7(Max-Min) + Min is determined and set as a threshold value

(iv)    The signal data is then compared to this value

(v)      If the data is > than the threshold the y-value = 1.

(vi)    If the data is < than the threshold the y-value = 0.

(vii)     This outputs a square wave of which the frequency can easily be determined.

i dont know how to go about with this. pls if any one can give me advice or guide me on the right track

[Shivam Awasthi]

Hi,

Please find the code for your query attached below. I suppose with a square wave of varying frequency you mean to refer to the duty cycle of the pulse. I also suggest that you go through some LabVIEW fundamentals or take up a LabVIEW basics course. That will enable you to build these codes on oyur own.

Best Regards,
Shivam Awasthi

[glee10]

To Mr.Shivam

thank you so much sir for helping me. i'll surely follow your advice and do a basic course in LABVIEW. 

thank you.

[Steve.J]

Please also see our on-line NI Biomedical User Group here:  www.ni.com/biomedusers

[glee10]

hello sir,

 i tried your given code with the EEG waveforms i had. it works fine but the square wave generated at the output has frequency of about .6hz whereas i want the frequency to be between 9hz to 12hz. how do i go about with it. what changes should i make and also am attaching my code. please guide me.