<![CDATA[Pulse sensors that utilize photoplethysmography (PPG) are commonly employed in biomedical monitoring, but their accuracy in readings is significantly compromised by high-frequency motion artifacts, changes in ambient light, and electrical interference. This research assesses the application of a passive Resistor-Capacitor (RC) Low-Pass Filter (LPF) combined with an Arduino Uno microcontroller to enhance the stability of real-time pulse monitoring. A testing approach was used to analyze output signals prior to and following filtration over sampling time ranges (2 ms to 4 ms) with a digital storage oscilloscope. Signal performance was assessed quantitatively by examining peak-to-peak voltage (Vp-p) variations and frequency stability. Empirical findings show that the LPF successfully reduced high-frequency noise and mitigated transient voltage spikes. Based on the assessed criteria, signal stability enhanced markedly from 70% in the unfiltered configuration to 100% after LPF implementation. The filtered analog signal delivered a dependable input for the ATmega328P microcontroller, facilitating precise real-time Beats Per Minute (BPM) calculations. In summary, adding a passive low-pass filter stage offers a reliable, inexpensive method to reduce environmental and hardware noise, greatly improving signal quality for portable physiological monitoring devices.]]>
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