emd.spectra.frequency_transform#
- emd.spectra.frequency_transform(imf, sample_rate, method, smooth_freq=3, smooth_phase=5)[source]#
Compute instantaneous phase, frequency and amplitude from a set of IMFs.
Several approaches are implemented from [1] and [2].
- Parameters:
- imfndarray
Input array of IMFs.
- sample_ratefloat
Sampling frequency of the signal in Hz
- method{‘hilbert’,’quad’,’direct_quad’,’nht’}
The method for computing the frequency stats
- smooth_phaseint
Length of window when smoothing the unwrapped phase (Default value = 31)
- Returns:
- IPndarray
Array of instantaneous phase estimates
- IFndarray
Array of instantaneous frequency estimates
- IAndarray
Array of instantaneous amplitude estimates
References
[1]Huang, N. E., Shen, Z., Long, S. R., Wu, M. C., Shih, H. H., Zheng, Q., … Liu, H. H. (1998). The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis. Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 454(1971), 903–995. https://doi.org/10.1098/rspa.1998.0193
[2]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