`FiltOctave`#

class acoular.tprocess.FiltOctave

Bases: Filter

Octave or third-octave bandpass filter (causal, with non-zero phase delay).

This class implements a bandpass filter that conforms to octave or third-octave frequency band standards. The filter is designed using a second-order section (SOS) Infinite Impulse Response (IIR) approach.

The filtering process introduces a non-zero phase delay due to its causal nature. The center frequency and the octave fraction determine the frequency band characteristics.

See also

Filter: The base class implementing a general IIR filter.
FiltFiltOctave: Octave or third-octave bandpass filter with zero-phase distortion.

band: The center frequency of the octave or third-octave band. Default is 1000.

fraction

Defines whether the filter is an octave-band or third-octave-band filter.

'Octave': Full octave band filter.
'Third octave': Third-octave band filter.

Default is 'Octave'.

order: The order of the IIR filter, which affects the steepness of the filter’s roll-off. Default is 3.

sos: Second-order sections representation of the filter coefficients. This property depends on band, fraction, order, and the source’s digest.

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

result(num)

Apply the IIR filter to the input signal and yields filtered data block-wise.

This method processes the signal provided by source, applying the defined filter coefficients (sos) using the scipy.signal.sosfilt() function. The filtering is performed in a streaming fashion, yielding blocks of filtered signal data.

Parameters:

numint: Number of samples per block.

Yields:

numpy.ndarray: An array containing the bandpass-filtered signal for the current block. Each block has the shape (num, num_channels), where num_channels is inherited from the source. The last block may contain fewer samples if the total number of samples is not a multiple of num.

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

sample_freq: Sampling frequency of output signal, as given by source.

num_channels: Number of channels in output, as given by source.

num_samples: Number of samples in output, as given by source.

FiltOctave#

`FiltOctave`#