emd.imftools.amplitude_normalise#

emd.imftools.amplitude_normalise(X, thresh=1e-10, clip=False, interp_method='pchip', max_iters=3)[source]#

Normalise the amplitude envelope of an IMF to be 1.

Multiple runs of normalisation are carried out until the desired threshold is reached. This uses the method described as part of the AM-FM transform [1]

Parameters:
Xndarray

Input array of IMFs to be normalised

threshfloat

Threshold for stopping normalisation (Default value = 1e-10)

clipbool

Whether to clip the output between -1 and 1 (Default value = False)

interp_method{‘pchip’,’mono_pchip’,’splrep’}

Method used to interpolate envelopes (Default value = ‘pchip’)

max_itersint

Maximum number of iterations of normalisation to perform

Returns:
ndarray

Amplitude normalised IMFs

References

[1]

Huang, N. E., Wu, Z., Long, S. R., Arnold, K. C., Chen, X., & Blank, K. (2009). On Instantaneous Frequency. Advances in Adaptive Data Analysis, 1(2), 177–229. https://doi.org/10.1142/s1793536909000096