IRISSeismic (version 1.0.7-1)

hilbertFFT: Hilbert FFT

Description

The hilbertFFT function returns the complex Hilbert FFT of a timeseries signal.

Usage

hilbertFFT(x)

Arguments

x

a numeric vector

Value

A complex vector containing the Hilbert FFT of x.

Details

This function is intended for internal use by the hilbert() and envelope() methods of Trace objects.

References

Seismic Attributes - A Review

Examples

  ## Not run: 
# # Open a connection to IRIS DMC webservices
# iris <- new("IrisClient")
# 
# starttime <- as.POSIXct("2010-02-27 06:00:00", tz="GMT")
# endtime <- as.POSIXct("2010-02-27 09:00:00", tz="GMT")
# 
# # Get the waveform
# st <- getDataselect(iris,"IU","ANMO","00","BHZ",starttime,endtime)
# tr <- st@traces[[1]]
# 
# # Demean, detrend, cosine taper
# tr <- DDT(tr)
# 
# # Calculate Hilbert FFT of the trace data
# hfft <- hilbertFFT(tr@data)
# 
# # Plot signal, with Hilbert envelope
# layout(1)
# plot(tr@data, type='l', col='gray80', main="Signal and Envelope")
# points(Mod(hfft), type='l', col='blue')
# 
# # 2 rows
# layout(matrix(seq(2)))
# 
# # Show that Imaginary component of Hilbert transform has the
# # original signal shifted by 90 degrees
# ccf(tr@data,tr@data,lag.max=200,main="Auto-correlation of signal data")
# ccf(tr@data,Im(hfft),lag.max=200,main="90 deg phase shift with Hilber transform")
# 
# # Restore default layout
# layout(1)
#   ## End(Not run)