CrossPowerSpectra¶

class acoular.fprocess.CrossPowerSpectra¶

Bases: AutoPowerSpectra

Compute the complex-valued auto- and cross-power spectra from frequency-domain data.

This class generates the cross-spectral matrix (CSM) in a flattened representation, which includes the auto-power spectra (diagonal elements) and cross-power spectra (off-diagonal elements). Depending on the calc_mode, the class can compute:

• The full CSM, which includes all elements.

• Only the upper triangle of the CSM.

• Only the lower triangle of the CSM.

The results are computed block-by-block and scaled according to the specified configuration.

source = Instance(SpectraGenerator)¶

The data source providing the input spectra, implemented as an instance of SpectraGenerator or a derived object.

precision = Enum('complex128', 'complex64', desc='precision of the fft')¶

Specifies the floating-point precision of the computed cross-spectral matrix (CSM). Options are 'complex128' and 'complex64'. Default is 'complex128'.

calc_mode = Enum('full', 'upper', 'lower', desc='calculation mode')¶

• 'lower': Computes only the lower triangle of the CSM,

  excluding redundant upper-triangle elements.

Default is 'full'.

num_channels = Property(depends_on=['source.num_channels'])¶

The number of channels in the output data. The value depends on the number of input channels \(n\) and the selected calc_mode:

• 'full': \(n^2\) (all elements in the CSM).

• 'upper': \(n + n(n-1)/2\) (diagonal + upper triangle elements).

• 'lower': \(n + n(n-1)/2\) (diagonal + lower triangle elements).

digest = Property(depends_on=['source.digest', 'precision', 'scaling', 'single_sided', 'calc_mode'])¶

A unique identifier based on the computation properties.

result(num=1)¶

Generate blocks of complex-valued auto- and cross-power spectra.

This generator computes the cross-spectral matrix (CSM) for input spectra block-by-block. Depending on the calc_mode, the resulting CSM is flattened in one of three ways:

• 'full': Includes all elements of the CSM.

• 'upper': Includes only the diagonal and upper triangle.

• 'lower': Includes only the diagonal and lower triangle.

Parameters:

numint, optional

Number of snapshots (blocks) in each output data block. Default is 1.

Yields:

numpy.ndarray

Blocks of complex-valued auto- and cross-power spectra with shape (num, :attr:`num_channels` * :attr:`num_freqs`). The last block may contain fewer than num elements if the input data does not completely fill the requested block size.