In case of a periodic disturbing signal as a "noise", special solutions for noise reduction can be applied. In literature, an adaptive noise canceller modification was proposed for this case by Strobach et al. [5] and applied by several other researchers. It uses an artificial reference signal, based on event triggered averaging of segments of the recorded wanted (but disturbed) signal in order to obtain a template for the repetitive distortion sequence which is used to construct the artificial reference signal. The simple subtraction and the adaptively modified template subtraction are also used, with better performance, to remove the repetitive noise component. Methods are basically introduced in simulations, and then demonstrated in real biosignal processing, considering the case of removing the disturbing maternal ECG from abdominal signals of pregnant women in order to get the fetal ECG for diagnosis purposes.