hht (version 2.1.6)

Sig2IMF: Empirical Mode Decomposition wrapper

Description

This function wraps the emd function in the EMD package. Sig2IMF is used in EEMD and others.

Usage

Sig2IMF(sig, tt, spectral.method = "arctan", diff.lag = 1, stop.rule = "type5", 
    tol = 5, boundary = "wave", sm = "none", smlevels = c(1), spar = NULL, 
    max.sift = 200, max.imf = 100, interm = NULL)

Value

emd.result

The intrinsic mode functions (IMFs), instantaneous frequencies, and instantaneous amplitudes of sig.

Arguments

sig

a time series to be decomposed (vector)

tt

A vector of sample times for sig

spectral.method

defines how to calculate instantaneous frequency - whether to use the arctangent of the analytic signal with numeric differentiation (``arctan'') or the result of the chain rule applied to the arctangent, then numerically differentiated ("chain"); see InstantaneousFrequency.

diff.lag

specifies if you want to do naive differentiation (diff.lag = 1), central difference method (diff.lag = 2 or higher difference methods (diff.lag > 2) to determine instantaneous frequency; see InstantaneousFrequency.

stop.rule

As quoted from the EMD package documentation: ''The stop rule of sifting. The type1 stop rule indicates that absolute values of envelope mean must be less than the user-specified tolerance level in the sense that the local average of upper and lower envelope is zero. The stopping rules type2, type3, type4 and type5 are the stopping rules given by equation (5.5) of Huang et al. (1998), equation (11a), equation (11b) and S stoppage of Huang and Wu (2008), respectively.''

tol

Determines what value is used to stop the sifting - this will depend on which stop rule you use.

boundary

how the beginning and end of the signal are handled

sm

Specifies how the signal envelope is constructed, see Kim et al, 2012.

smlevels

Specifies what level of the IMF is obtained by smoothing other than interpolation, see EMD package documentation

spar

User-defined smoothing parameter for spline, kernel, or local polynomial smoothing.

max.sift

How many sifts are allowed - if this value is exceeded the IMF is returned as-is.

max.imf

Maximum number of IMFs allowed.

interm

Specifies vector of periods to be excluded from IMFs to cope with mode mixing.

Details

This function configures and performs empirical mode decomposition using the emd function in the EMD package.

References

Kim, D., Kim, K. and Oh, H.-S. (2012) Extending the scope of empirical mode decomposition by smoothing. EURASIP Journal on Advances in Signal Processing, 2012, 168.

Huang, N. E., Shen, Z., Long, S. R., Wu, M. L. Shih, H. H., Zheng, Q., Yen, N. C., Tung, C. C. and Liu, H. H. (1998) The empirical mode decomposition and Hilbert spectrum for nonlinear and nonstationary time series analysis. Proceedings of the Royal Society London A, 454, 903--995.

Huang, N. E. and Wu Z. A. (2008) A review on Hilbert-Huang Transform: Method and its applications to geophysical studies. Reviews of Geophysics, 46, RG2006.

See Also

EEMD, PlotIMFs

Examples

data(PortFosterEvent)

#Run EMD
emd.result=Sig2IMF(sig, tt)

#Display IMFs

time.span <- c(5, 10)
imf.list <- 1:3
original.signal <- TRUE
residue <- TRUE

PlotIMFs(emd.result, time.span, imf.list, original.signal, residue)

#Plot spectrogram
sdt <- tt[2] - tt[1]
dfreq <- 0.25
freq.span <- c(0, 25)
hgram <- HHRender(emd.result, sdt, dfreq, freq.span = freq.span, verbose = FALSE)

time.span <- c(4, 10)
freq.span <- c(0, 25)
amp.span <- c(0.000001, 0.00001)
HHGramImage(hgram, time.span = time.span, 
freq.span = freq.span, amp.span = amp.span,
pretty = TRUE)