The ECG represents cardiac electrical activity recorded by electrodes placed at a distance from the heart, on the surface of the body. During a cardiac electrical activity recording session, artifacts like baseline wander, powerline interference, EMG noise and electrode motion artifact are present in addition to the ECG signal. These are unwanted signals that are mixed with the ECG signal and can lead to erroneus interpretations or diagnoses. Therefore, they must be eliminated from ECG signals using appropriate signal denoising techniques. The aim of this work is to find the best denoising technique for ECG signal in a given context: the proposed denoising technique must be suitable to be applied with a real time approach to real noisy signals acquired with a wearable device.