signal analysis - how to remove unwanted signal

[Coq_Rouge]

I agree with Lynn. You have a lot of baseline drifting in your signal. I think you should use a highpass filter to block out the DC. The best thing is probably to do this by some circuits in the instrument frontend. But you may also use digital filters in Labview. I would have use something in the range 0.2 to 0.5 Hz as cutoff for the highpass filter. You should also use a much higher sample rate like some Khz, this will improve the filtering. A trick I often use is to sample with a much higher sample rate than needed. Then I apply my signal processing. But then the signal is cleaned up. I often downsample by averaging before viewing or storing the data. Averaging may also in many cases contribute to clean up a signal.