microvolts range of raw channel data
What is the proper method to covert raw channel data to microvolts? I am trying the following:
1. convert 24-bit 2s compliment hex to decimal value between -2^23 and 2^23
2. apply user specified gain dependent scaling factor, where scale_fac_uVolts_per_count = ADS1299_Vref/((2.0**23)-1)/(ADS1299_gain * 10.0e5).
However, this number is very small, and results in a uVolt range of -1.875e-7 to 1.875e-7. Is this truly the range of voltage that the EEG is pulling from the scalp electrodes?
1. convert 24-bit 2s compliment hex to decimal value between -2^23 and 2^23
2. apply user specified gain dependent scaling factor, where scale_fac_uVolts_per_count = ADS1299_Vref/((2.0**23)-1)/(ADS1299_gain * 10.0e5).
However, this number is very small, and results in a uVolt range of -1.875e-7 to 1.875e-7. Is this truly the range of voltage that the EEG is pulling from the scalp electrodes?
Comments
http://docs.openbci.com/software/02-OpenBCI_Streaming_Data_Format
At the default 24x gain, this results in samples that can range from -187500 uV to +187500 uV.
Or 0.02235 uV per count of the 24 bit samples.
William