OctaveFilterBank

class acoular.tprocess.OctaveFilterBank

Bases: FilterBank

Octave or third-octave filter bank.

Inherits from FilterBank and implements an octave or third-octave filter bank. This class is used for filtering multi-channel time series data, such as time signal signals, using bandpass filters with center frequencies at octave or third-octave intervals.

See also

FilterBank

The base class for implementing IIR filter banks.

SamplesGenerator

Interface for generating multi-channel time domain signal processing blocks.

scipy.signal

SciPy module for signal processing.

lband

The lowest band center frequency index. Default is 21. This index refers to the position in the scale of octave or third-octave bands.

hband

The highest band center frequency index + 1. Default is 40. This is the position in the scale of octave or third-octave bands.

fraction

The fraction of an octave, either 'Octave' or 'Third octave'. Default is 'Octave'. Determines the width of the frequency bands. ‘Octave’ refers to full octaves, and 'Third octave' refers to third-octave bands.

ba

The list of filter coefficients for all filters in the filter bank. The coefficients are computed based on the lband, hband, and fraction attributes.

bands

The list of labels describing the frequency bands in the filter bank.

num_bands

The total number of bands in the filter bank.

digest

A unique identifier for the filter, based on its properties. (read-only)

result(num)

Yield the bandpass filtered output of the source in blocks of samples.

This method uses the second order section coefficients (sos) to filter the input samples provided by the source in blocks. The result is returned as a generator.

Parameters:

numint

Number of samples per block.

Yields:

numpy.ndarray

An array of shape (num, num_channels), delivering the filtered samples for each band. The last block may contain fewer samples if the total number of samples is not a multiple of num.

Notes

The returned samples are bandpass filtered according to the coefficients in sos. Each block corresponds to the filtered samples for each frequency band.

source

The input data source. It must be an instance of a SamplesGenerator-derived class.

sos

The list containing second order section (SOS) coefficients for the filters in the filter bank.

num_channels

The total number of output channels resulting from the filter bank operation.

sample_freq

Sampling frequency of output signal, as given by source.

num_samples

Number of samples in output, as given by source.