Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Illustration plot of PPG signal slice and Fast Fourier Transform Frequency Domain after Butterworth Bandpass Filtering. a—d) present signal morphology before and after Butterworth bandpass filter of orders 2, 4, and 6, respectively, with fixed frequency threshold [0.5, 8] Hz. e—h) present corresponding Power Spectral Density by Fast Fourier analysis. As subplot (g) shows, noise exists with a lower frequency and is diminished after filtering. SNR: Signal–Noise Ratio
