lowpass_cheby_2(data, freq, df, maxorder=12, ba=False, freq_passband=False)[source]

Cheby2-Lowpass Filter

Filter data by passing data only below a certain frequency. The main purpose of this cheby2 filter is downsampling. #318 shows some plots of this filter design itself.

This method will iteratively design a filter, whose pass band frequency is determined dynamically, such that the values above the stop band frequency are lower than -96dB.

  • data (numpy.ndarray) Data to filter.
  • freq The frequency above which signals are attenuated with 95 dB
  • df Sampling rate in Hz.
  • maxorder Maximal order of the designed cheby2 filter
  • ba If True return only the filter coefficients (b, a) instead of filtering
  • freq_passband If True return additionally to the filtered data, the iteratively determined pass band frequency

Filtered data.