sdynpy.core.sdynpy_data.ImpulseResponseFunctionArray

• Module: sdynpy.core.sdynpy_data

• Source: GitHub

• Parent: sdynpy.NDDataArray

• Parent: sdynpy.SdynpyArray

• Parent: numpy.ndarray

Signature¶

class sdynpy.core.sdynpy_data.ImpulseResponseFunctionArray(shape, nelements, buffer=None, offset=0, strides=None, order=None)

Data array used to store impulse response functions

Attributes¶

function_type¶

Returns the function type of the data array

Methods¶

enforce_causality¶

• Source: GitHub

def sdynpy.core.sdynpy_data.ImpulseResponseFunctionArray.enforce_causality(self, method='exponential_taper', window_parameter=None, end_of_ringdown=None)

Enforces causality on the impulse response function via a cutoff of some sort.

Parameters¶

• method : str The window type that is applied to the data to enforce causality. Note that these options are not necessarily traditional windows (used for data processing). The current options are:

  • exponential_taper (default) - this applies a exponential taper to the end of a boxcar window on the IRF.

  • boxcar - this applies a boxcar (uniform) window to the IRF with the cuttoff at a specified sample.

  • exponential - this applies an exponential window to the IRF with the 40 dB down point (of the window) at a specified sample. Care should be taken when using this window type, since it can lead to erratic behavior.

• window_parameter : int, optional This is a parameter that defines the window for the causality enforcement. Methods exist to define this parameter automatically if it isn’t provided. The behaviors for the options are:

  • boxcar - the window_paramter is the sample after which the IRF is set to zero. It is the same as the end_of_ringdown parameter for this window type.

  • exponential - the window_parameter is where the 40 dB down point is for the window. It is the same as the end_of_ringdown parameter for this window type.

  • exponential_taper - the window_parameter is where the end point of the window (where the amplitude is 0.001), as defined by the number of samples after the uniform section of the window.

• end_of_ringdown : int, optional This is a parameter that defines the end of the uniform section of the exponetional_taper window. It is not used for either the boxcar or exponential window. Methods exist to define this parameter automatically if it isn’t provided.

Returns¶

• ImpulseResponseFunctionArray

• The IRF with causality enforced.

Notes¶

Although optional, it is best practice for the user to supply a parameter for the end_of_ringdown variable if the “exponential_taper” method is being used or a window_parameter if the “exponential” or “boxcar” methods are being used. The code will attempt to find the end of the ring-down in the IRF and use use that as the end_of_ringdown parameter for the “exponential_taper” window or the window_parameter for the exponential and boxcar windows.

It is not suggested that the user provide a window_paramter if the “exponential_taper” method is being used, since the default is likely the most logical choice.

References¶

.. [1] Zvonkin, M. (2015). Methods for checking and enforcing physical quality of linear electrical network models [Masters Theses, Missouri University of Science and Technology], Missouri S&T Scholars’ Mine, https://scholarsmine.mst.edu/masters_theses/7490/

fft¶

• Source: GitHub

def sdynpy.core.sdynpy_data.ImpulseResponseFunctionArray.fft(self, norm='backward', **scipy_rfft_kwargs)

Converts the impulse response function to a frequency response function using the fft function.

Returns¶

• TransferFunctionArray

• The transfer function array computed from the impusle response function

• array.

Paramters¶

norm : str, optional The type of normalization applied to the fft computation. scipy_rfft_kwargs : Additional keywords that will be passed to SciPy’s rfft function.

find_end_of_ringdown¶

• Source: GitHub

def sdynpy.core.sdynpy_data.ImpulseResponseFunctionArray.find_end_of_ringdown(self)

Finds the end of the ringdown in a impulse response function (IRF).

It does this by smoothing the IRF via a moving average filter, then finding the index of the minimum of the smoothed IRF (for each response/reference pair). The “end of ringdown” is defined as the median of the possible indices.

Returns¶

• end_of_ringdow : int Index that represents the end of the ringdown for the supplied IRFs.