Comments

• There is a very important reason why AC is used when doing GSR. Electrodes represent 1/2 of a battery, they are in fact what are called half cells. Consider an ordinary D-cell battery for instance it has a carbon electrode and a zinc cathode. Many o…

  in GSR & OpenBCI Comment by cybin September 2014
• Please refer to page 22 of the ADS1299 data sheet.From the properties of the sinc filter and Figure 26 that for a filter of with a 250 Hz sample rate we can expect a signal at 62.5 Hz 1/4 the normalized frequency to be reduced about 2.7 dB. So... th…

  in 50hz power filter rather than 60hz power filter Comment by cybin September 2014
• Keep in mind that the EEG is a very, very, very tiny signal that exists in the presence of many other signals that are HUGE by comparison. To see these tiny signals in the presence of all the other crap it is necessary to preserve the dynamic range …

  in Where Are the High Gain Amps? Comment by cybin September 2014
• Actually, I believe the sampling rate is selected to produce a null at 60 Hz. If you wish to move the null to 50 Hz you'll need to slow down the sampling rate to achieve the same effect. You can see this if you take a look at the FFT spectrum data f…

  in 50hz power filter rather than 60hz power filter Comment by cybin September 2014