Efficient adquisition and data storage (OpenBCI)
Posted: Tue Mar 13, 2018 4:51 am
Hi everyone,
I'm currently working in polysomnography analysis.
I use a hardware composed by a Pi3 and OpenBCI, with daisy module, that allowed me to adquire 16 channels at 125hz. My software is openvibe (1.2.2) acquisition server/design for a small live view and csv data storage.
Today i complete my first 30min of adquisition successfully and write a .csv file with that data. Later i try to playback that session with same display, filters, etc configuration than live, but looks like a poor quality visualization. Specialy in 12-channels correspond to EEG data, seems less density data plot and poor detail of lines trace.
Try with EDFbrowser for visualice the session and same results, poor quality of signal, like if some data was lose in the write .csv process.
Some ideas about what could are happening?
I check the numbers of samples in .csv output and its ok (30min at 125hz is aprox 225k samples). Default configuration in server adquisition and drive properties was used.
One things i noted is that bar drift scale to full right in like 3seg and keep full as long adquisition is on.
I don't know if is directly related with my problem, i read in 2.0 version drift is disable and for <1.3 default configuration driver decide. I'm wondering whats configuration would be best for priorise my data quality?? Maybe write a 32bits data directly to the SD card provide in OpenBCI module?
Hope someone can help me.
Cheers!
I'm currently working in polysomnography analysis.
I use a hardware composed by a Pi3 and OpenBCI, with daisy module, that allowed me to adquire 16 channels at 125hz. My software is openvibe (1.2.2) acquisition server/design for a small live view and csv data storage.
Today i complete my first 30min of adquisition successfully and write a .csv file with that data. Later i try to playback that session with same display, filters, etc configuration than live, but looks like a poor quality visualization. Specialy in 12-channels correspond to EEG data, seems less density data plot and poor detail of lines trace.
Try with EDFbrowser for visualice the session and same results, poor quality of signal, like if some data was lose in the write .csv process.
Some ideas about what could are happening?
I check the numbers of samples in .csv output and its ok (30min at 125hz is aprox 225k samples). Default configuration in server adquisition and drive properties was used.
One things i noted is that bar drift scale to full right in like 3seg and keep full as long adquisition is on.
I don't know if is directly related with my problem, i read in 2.0 version drift is disable and for <1.3 default configuration driver decide. I'm wondering whats configuration would be best for priorise my data quality?? Maybe write a 32bits data directly to the SD card provide in OpenBCI module?
Hope someone can help me.
Cheers!