HammingFilter
Hamming windowed FIR filter with pedestal.
Usage
Apply as a windowing function before DFT-based cycle detection to reduce sidelobe leakage and obtain cleaner dominant cycle estimates.
Background
The Hamming window is a raised-cosine weighting function that reduces spectral leakage by tapering the edges of a data block. Ehlers uses it in DFT-based cycle measurement tools to prevent energy in one frequency bin from contaminating adjacent bins, improving cycle period resolution.
Parameters
length(default: 20): Filter lengthpedestal(default: 10.0): Pedestal in degrees
Formula
[ Deg(n) = Pedestal + (180 - 2 \times Pedestal) \times \frac{n}{L-1} ] [ Coef(n) = \sin\left(\frac{Deg(n) \times \pi}{180}\right) ] [ Filt = \frac{\sum_{n=0}^{L-1} Coef(n) \cdot Price_{t-n}}{\sum Coef(n)} ]