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Cross-spectral density between two signals

Source: R/coupling-spectral.R
crossSpectrum.Rd

Computes the cross-spectral density (CSD) between two signals using Welch's method. The CSD captures both the magnitude and phase relationship between two signals as a function of frequency.

Usage

crossSpectrum(
  x,
  y = NULL,
  sr = NULL,
  nperseg = 256L,
  noverlap = NULL,
  modality_x = NULL,
  modality_y = NULL,
  channels_x = 1L,
  channels_y = 1L
)

Arguments

x

Numeric vector, PhysioExperiment, or MultiPhysioExperiment.

y

Numeric vector or PhysioExperiment, or NULL when x is an MPE.

sr

Numeric sampling rate in Hz (required when x/y are numeric).

nperseg

Integer segment length for Welch's method (default 256).

noverlap

Integer overlap between segments, or NULL for floor(nperseg / 2).

modality_x

Character modality name in MPE for the x signal.

modality_y

Character modality name in MPE for the y signal.

channels_x

Integer which channel to extract from x (default 1).

channels_y

Integer which channel to extract from y (default 1).

Value

A named list with components:

csd

Complex vector of cross-spectral density values.

frequencies

Numeric vector of corresponding frequencies in Hz.

magnitude

Numeric vector of CSD magnitude (Mod(csd)).

phase

Numeric vector of CSD phase in radians (Arg(csd)).

References

Carter, G. C. (1987). Coherence and time delay estimation. Proceedings of the IEEE, 75(2), 236–255.

Halliday, D. M., Rosenberg, J. R., Amjad, A. M., Breeze, P., Conway, B. A., & Farmer, S. F. (1995). A framework for the analysis of mixed time series/point process data – theory and application to the study of physiological tremor, single motor unit discharges and electromyograms. Progress in Biophysics and Molecular Biology, 64(2–3), 237–278.

See also

coherence(), multitaperCoherence(), couplingAnalysis()

Examples

sr <- 500
t <- seq(0, 5, length.out = sr * 5)
x <- sin(2 * pi * 10 * t) + 0.1 * rnorm(length(t))
y <- cos(2 * pi * 10 * t) + 0.1 * rnorm(length(t))
result <- crossSpectrum(x, y, sr = sr)
plot(result$frequencies, result$magnitude, type = "l",
     xlab = "Frequency (Hz)", ylab = "|CSD|")