Calculate 'Welch Periodogram'

pwelch is for single signal trace only; mv_pwelch is for multiple traces. Currently mv_pwelch is experimental and should not be called directly.

Usage

pwelch(
  x,
  fs,
  window = 64,
  noverlap = 8,
  nfft = 256,
  col = "black",
  xlim = NULL,
  ylim = NULL,
  main = "Welch periodogram",
  plot = 0,
  log = c("xy", "", "x", "y"),
  ...
)

# S3 method for pwelch
print(x, ...)

# S3 method for pwelch
plot(
  x,
  log = c("xy", "x", "y", ""),
  se = FALSE,
  xticks,
  type = "l",
  add = FALSE,
  col = graphics::par("fg"),
  col.se = "orange",
  alpha.se = 0.5,
  lty = 1,
  lwd = 1,
  cex = 1,
  las = 1,
  main = "Welch periodogram",
  xlab,
  ylab,
  xlim = NULL,
  ylim = NULL,
  xaxs = "i",
  yaxs = "i",
  xline = 1.2 * cex,
  yline = 2 * cex,
  mar = c(2.6, 3.8, 2.1, 0.6) * (0.5 + cex/2),
  mgp = cex * c(2, 0.5, 0),
  tck = -0.02 * cex,
  grid = TRUE,
  ...
)

mv_pwelch(x, margin, fs, nfft)

Arguments

x

numerical vector or a row-major vector, signals. If x is a matrix, then each row is a channel. For plot function, x is the instance returned by pwelch function.

fs

sample rate, average number of time points per second

window

window length in time points, default size is 64

noverlap

overlap between two adjacent windows, measured in time points; default is 8

nfft

number of basis functions to apply

col, xlim, ylim, main, type, cex, las, xlab, ylab, lty, lwd, xaxs, yaxs, mar, mgp, tck

parameters passed to plot.default

plot

integer, whether to plot the result or not; choices are 0, no plot; 1 plot on a new canvas; 2 add to existing canvas

log

indicates which axis should be log10-transformed, used by the plot function. For 'x' axis, it's log10-transform; for 'y' axis, it's 10log10-transform (decibel unit). Choices are "xy", "x", "y", and "".

...

will be passed to plot.pwelch or ignored

se

logical or a positive number indicating whether to plot standard error of mean; default is false. If provided with a number, then a multiple of standard error will be drawn. This option is only available when power is in log-scale (decibel unit)

xticks

ticks to show on frequency axis

add

logical, whether the plot should be added to existing canvas

col.se, alpha.se

controls the color and opacity of the standard error

xline, yline

controls how close the axis labels to the corresponding axes

grid

whether to draw rectangular grid lines to the plot; only respected when add=FALSE; default is true

margin

the margin in which pwelch should be applied to

Value

A list with class 'ravetools-pwelch' that contains the following items:

freq

frequencies used to calculate the 'periodogram'

spec

resulting spectral power for each frequency

window

window function (in numerical vector) used

noverlap

number of overlapping time-points between two adjacent windows

nfft

number of basis functions

fs

sample rate

x_len

input signal length

method

a character string 'Welch'

Examples

x <- rnorm(1000)
pwel <- pwelch(x, 100)
pwel
#> Welch Periodogram:
#>   # channels: 1
#>   time points: 1000
#>   sample rate: 100.00
#>   window size: 64
#>   window overlaps: 8
#>   filter count: 256

plot(pwel, log = "xy")