Hi ,
I am working in an university in Singapore with Biosemi system + Actiview V3.38.
I need to extract data from 1 channel during Data Acquistion.
However , i am confused on the format in which the data are being stored and the conventional Chart is unable to display the data correct.
The Data that is displayed during Data Acquistion is a 2D Array but i am unable to determine the exact strucuture of the array.
How is the Mon Chart created to accept the current format of Data ?
I would be very grateful if someone could enlighten me on the 2 issue mentioned above.
Regards Ken
On-line Extraction of Data from Single Channel
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Coen
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Use the 2D array coming from the subvi Downsample-24sinc.vi. This array contains the raw data, and is used for the subvi's that calculate the chart traces, and for the data set saved to file. Do not use the arrays going directly to the charts: the data at that point is referenced, filtered, baseline corrected, and DC shifted.
The 2D array with raw data has a simple structure: rows are channels, columns are sample moments. The number of samples (columns) is varying with each sweep because ActiView is constantly adjusts the number of points written to screen according to the backlog and available processor time.
Use the "index array" function to extract two channels from the array, use "subtract" to calculate a differential lead. This resulting 1D array can be used for further on-line processing, or aa an input for an additional chart (be sure to turn the "transpose array" option off). Note that you will probably will have to remove the electrode offsets before further processing (for example: apply a high-pass filter)
Best regards, Coen (BioSemi)
The 2D array with raw data has a simple structure: rows are channels, columns are sample moments. The number of samples (columns) is varying with each sweep because ActiView is constantly adjusts the number of points written to screen according to the backlog and available processor time.
Use the "index array" function to extract two channels from the array, use "subtract" to calculate a differential lead. This resulting 1D array can be used for further on-line processing, or aa an input for an additional chart (be sure to turn the "transpose array" option off). Note that you will probably will have to remove the electrode offsets before further processing (for example: apply a high-pass filter)
Best regards, Coen (BioSemi)
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Ken
Monopolar Display Channel Voltage Value
Good Day ,
May i enquire on the intepretation of the voltage reading for each channel? Should i assume that the downward imply positive and upward imply negative?
For the Y-scale Volts/div :
does that imply the gap between 2 channel is equivalent to the value selected.
i.e if Channel F1 , F2 is selected with Voltage/div of 100uV
then the gap difference between F1 and F2 on the chart is equivalent
to 100uV.
Thanks for your help in advance.
Regards Ken
May i enquire on the intepretation of the voltage reading for each channel? Should i assume that the downward imply positive and upward imply negative?
For the Y-scale Volts/div :
does that imply the gap between 2 channel is equivalent to the value selected.
i.e if Channel F1 , F2 is selected with Voltage/div of 100uV
then the gap difference between F1 and F2 on the chart is equivalent
to 100uV.
Thanks for your help in advance.
Regards Ken