I am getting the attached periodical signal, instead of a constant value. Amplitude and frequency are always the same (do not depend on the average value). Is there a better way, than just averaging over 1 period to get a constant signal?
Averaging your signal over 1 period would provide a constant value from your periodic data. You could also implement some filtering because a low pass filter would attenuate high frequencies. If the periodic signal is not expected in your data you may need to look at your signal connections. Switching your connection to differential can help remove coupled frequencies from your resulting data. You may want to add shielding to your cables to reduce coupled frequencies. If you are still having trouble it may be helpful to provide some additional context to your issue such as the frequency of the noise and some additional information about what you are measuring. I would recommend that you look through the following Developer Zone Article about field wiring for additional information about solving noise problems.
