<![CDATA[Photopethysmography (PPG) signal is a physiological signal that is very vulnerable to noise disorders, especially from the artifacts of environmental movements and interference. This noise can reduce the accuracy of signal analysis, disrupt the feature extraction process, and cause errors for interpretation of physiological conditions. This study aims to improve the quality of PPG signals through the denoising process using Butterworth filters, as well as evaluating signal accuracy increases based on amplitude statistics and signal ratios to noise (Signal-to-Noise Ratio/SNR). The main contribution of this study is to show the effectiveness of the Butterworth filter configuration (Lowpass and Bandpass) with various orders in increasing PPG signal SNR and strengthening the stability of signal amplitude as a basis for more accurate physiological analysis. The filtering process using Butterworth Filter is applied with the order variation (2, 4, 6) and the configuration of lowpass or bandpass. Evaluation is carried out based on changes in the value of SNR and statistical parameters amplitude (mean, median, standard deviation). The results showed a significant increase in SNR from an average of 8.26 dB to 18.8 dB after filtering, with the highest increase of +12.1 dB using the bandpass order 4. Amplitude statistics showed an increase in stability, where the mean changed from 0.398 MV to 0.409 MV, the median from 0.400 mV to 0.415 MV, and the standard deviation increased from 0.053 MV to 0.078 MV, more consistent signal distribution post-filtering. Butterworth filter proved effective in improving the quality of PPG signals by pressing noise significantly and maintaining the integrity of the main signal. These results indicate that this approach can be used as an important initial step in the PPG signal -based health analysis system, such as heart rate detection or vascular variability.]]>
