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