signal_spectrogram: Calculate spectrograms (power spectral density estimates)...

In coffeemuggler/eseis: Environmental Seismology Toolbox

Calculate spectrograms (power spectral density estimates) from time series.

Description

This function creates spectrograms from seismic signals. It supports the standard spectrogram approach and the Welch method.

Usage

signal_spectrogram(
  data,
  time,
  dt,
  Welch = FALSE,
  window,
  overlap = 0.5,
  window_sub,
  overlap_sub = 0.5,
  method = "periodogram",
  cpu = NULL,
  plot = FALSE,
  ...
)

Arguments

data	Numeric vector or list of vectors, seismic signal to be processed.
time	POSIX.ct vector with time values. If omitted, an artificial time vector will be created, based on dt. Only needed if data is no eseis object.
dt	Numeric value, sampling period. If omitted, either estimated from time or set to 0.01 s (i.e., f = 100 Hz). Only needed if data is no eseis object.
Welch	Logical value, option to use the Welch method for calculations.
window	Numeric value, time window length in seconds used to calculate individual spectra. Set to 1 percent of the time series length by default.
overlap	Numeric value, fraction of window overlap.
window_sub	Numeric value, length of the sub-window in seconds used to calculate spectra. Only relevant if Welch = TRUE. If omitted, the sub-window length is set to 10 percent of the main window length.
overlap_sub	Numeric value, fraction of sub-window overlap.
method	Character value, method to calculate the spectra. One out of "periodogram" and "autoregressive". Default is "periodogram".
cpu	Numeric value between 0 and 1, fraction of CPU cores to use. If omitted, only one CPU is used.
plot	Logical value, toggle plot output. Default is FALSE. For more customised plotting see plot_spectrogram.
...	Additional arguments passed to the function.

Details

Data containing NA values is replaced by zeros and set to NA in the output data set.

Value

List with spectrogram matrix, time and frequency vectors.

Author(s)

Michael Dietze

Examples

## load example data set
data("earthquake")

## calculate and plot PSD straight away
P <- signal_spectrogram(data = s$BHZ, 
                               time = t, 
                               dt = 1 / 200, 
                               plot = TRUE)

## calculate and plot PSD with defined window sizes and the Welch method
P <- signal_spectrogram(data = s$BHZ, 
                               time = t, 
                               dt = 1 / 200, 
                               window = 5, 
                               overlap = 0.9, 
                               window_sub = 3, 
                               overlap_sub = 0.9, 
                               Welch = TRUE,
                               plot = TRUE)
                      

coffeemuggler/eseis documentation built on Aug. 19, 2023, 9:57 p.m.