This post describes low-pass filters and high-pass filters.
Low -pass filter
A low-pass filter (LPF) is a filter that passes only low-frequency signals and attenuates high-frequency signals.
Purpose:
- Noise Reduction
- Smoothing of analog signals
- Anti-aliasing before sampling
Calculation Formula: y[n] = αx[n] + (1-α)y[n-1] α range 0 to 1.0
High-pass filter
A high-pass filter (HPF) is a filter that removes low-frequency components from a signal while retaining high-frequency components.
Purpose:
- Offset removal for accelerometers
- DC offset removal of audio signals
- Control System Fluctuation Detection
Calculation Formula: y[n] = α(y[n-1] + x[n] – x[n-1]) α range 0 to 1.0