lowpass#

PySeismoSoil.helper_signal_processing.lowpass(orig_signal: ndarray, cutoff_freq: float, show_fig: bool = False, filter_order: int = 4, padlen: int | None = None) → ndarray[source]#

IIR low pass filter with zero phase distortion.

Parameters:

  • orig_signal (np.ndarray) – The signal to be filtered (2 columns).

  • cutoff_freq (float) – Cut-off frequency, in Hz

  • show_fig (bool) – Whether to show a figure of before/after spectra

  • filter_order (int) – Filter order.

  • padlen (int | None) – Pad length (the number of elements by which to extend x at both ends of axis before applying the filter). If None, use the default value. (https://docs.scipy.org/doc/scipy/reference/generated/scipy.signal.filtfilt.html)

Returns:

filtered – Filtered signal, in two columns, where the 0th is the time and the 1st is the signal value.

Return type:

np.ndarray