Dear Kris
This are my measure equipment , I use the alligator clip to connect my electrode and evaluation board,use battery as my power source and scope the output to observe the waveform, Today I ask my colleagues to retest again, The result looks is different in different people, someone is better and someone is worse, I made a assumption .Because the gain is constant and different people has different different heart rate voltage, but the noise(might be ground noise) also constant. So, if the heart rate voltage is weak, the ground noise's influence would become serious.Like the following formula, ECG signal= A(gain)*heart rate +noise
Do you have good idea to reduce this noise?
Thanks!
KJ
