I have a signal that runs for 1 year. I'm only interested on the signal with frequency within 0.01 to 0.1 Hz. How do I extract this range of signal? I have tried several methods but I'm not sure if I did it correctly. For instance, I have tried using a function from this particular user (link: https://www.mathworks.com/matlabcentral/fileexchange/25017-fft-filter-clean-your-signals-and-display-results-) but the output doesn't seem right (refer picture). The "filtered" signal looks too weak and it's even symmetrical. I don't think that's possible since the original signal is anything but left-right symmetrical. Please help me.
Thanks!
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