Can we adjust the filter settings on a BioSemi system ?
Yes, but only in software.
With the ActiveTwo, all filtering is digital. High-pass filtering (if any) is completely performed in software, the hardware is completely DC coupled. Low pass filtering is performed in the ADC's decimation filter (hardware bandwidth limit), which has a 5th order sinc response with a -3 dB point at 1/5th of the selected sample rate, see filter graph. Further variable bandwidth limiting (high and low pass) can be applied at will in software.
Because of BioSemi's unique setup with active electrodes, battery power supply, and optic fiber signal link, 50 Hz interference is eliminated from the recordings. Therefore, reverting to signal corrupting patches like 50 Hz notch filters is never needed.
The completely digital filter methods used in the ActiveTwo (in the ADC or by software) eliminates response differences between channels. While the accuracy of analog filtering is compromised by component tolerances (5% for typical filter capacitors), digital filtering ensures completely equal frequency response for all channels.
Click here for information about adjusting the filter on older BioSemi systems