The principle of signal filtering

[Z-Xiong]

https://github.com/pi-null-mezon/vpglib/blob/3179139baac8465f6717f773e5ad0e7111939e10/Library/src/pulseprocessor.cpp#L63 Is the function of filtering here to smooth the signal? What is the principle of smoothing? My experiments tell me that when choosing different m_filterlength and m_interval, the impact on the results is relatively large.