sdynpy.signal_processing.sdynpy_frf.fft2frf

fft2frf(references, responses, method='H1', freqs_in=None, **kwargs)[source]

Creates an FRF matrix given ffts of responses and references

This function creates a nf x no x ni FRF matrix from the ffts provided.

Parameters

  • references (ndarray) – A ni x nf or nf array where ni is the number of references and nt is the number of frequencies in the fft.

  • responses (ndarray) – A no x nf or nf array where no is the number of responses and nf is the number of time frequencies in the fft.

  • method (str in ['H1','H2','Hv','Hs','LRM']) – The method for creating the frequency response function.

  • freqs_in (ndarray) – Only used if method == ‘LRM’. A nf or nf x 1 array of frquency values.

  • **lrm_kwargs – Additional keyword arguments specify parameters if method == ‘LRM’. Possible arguments are: f_out (ndarray), bandwidth (float), transient (boolean), modelset (iterable of (3,1) ndarray), max_parallel (int), export_ratio (float). See sdynpy_lrm.frf_local_model.

Returns

  • H (ndarray) – A nf x no x ni array where nf is the number of frequency lines, no is the number of outputs, and ni is the number of inputs. The output frequency lines will correspond to the frequency lines in the ffts.

  • freqs_out (None or ndarray) – None unless method == ‘LRM’. See sdynpy_lrm.frf_local_model.

  • model_data (None dict) – None unless method == ‘LRM’. See sdynpy_lrm.frf_local_model.

Notes

There are requirements for the shapes of references and responses for some FRF computation methods. No averaging is performed by this function.