EvolutiveFFT {hht}

Calculate the evolutive Fourier spectrogram.

Description

Generates the evolutive Fourier spectrogram of a signal, and returns it for use in FTGramImage.

Usage

EvolutiveFFT(sig, dt, ft, freq.span, taper = 0.05)

Arguments

sig

Signal to analyze.

dt

Sample rate (must be constant).

ft

Fourier transform input parameters

• ft$nfft The frequency resolution, should be in powers of 2

• ft$ns Number of samples in a window

• ft$nov Number of samples to overlap, must be less than ft$ns

freq.span

Frequency range to return.

taper

Amount of cosine taper to apply.

Details

This is an internal function and users will likely not call it directly.

Value

z

Power spectrum

y

Frequency

x

Time

original.signal

The input signal

tt

Sample times based on input sample rate dt

Note

This is a modification of the evolfft function in the RSEIS package.

Author(s)

Daniel C. Bowman [e-mail], Jonathan M. Lees

References

Jonathan M. Lees (2012). RSEIS: Seismic Time Series Analysis Tools. R package version 3.1-3.