I am trying to record respiration using this PZT belt, and a BITalino plugged kit.
However, the signal quality is highly unpredictable.
Sometimes, it is as clean as this:
Sometimes a little noisy:
And sometimes unusable (those peaks do not seem to be breaths even):
The unusable one is the most common.
All these signals are acquired in the same environment and using the same procedure. Are there any known interference sources for these belts?