Compute a time-frequency spectrogram — compute

Generates a short-time Fourier transform (STFT) based spectrogram for a single PSG channel across all epochs. Returns power (µV²/Hz) as a matrix with time (epochs) on rows and frequency on columns.

Usage

compute_spectrogram(
  psg,
  channel = NULL,
  freq_range = c(0, 40),
  window_s = 2,
  overlap = 0.5,
  db = TRUE
)

Arguments

psg: An mrpheus_psg object from prepare_psg().
channel: Character. A single channel label.
freq_range: Numeric vector of length 2. Frequency range to return (Hz). Default c(0, 40).
window_s: Numeric. STFT window length in seconds. Default 2.
overlap: Numeric in [0, 1). Fractional window overlap. Default 0.5.
db: Logical. Return power in decibels (10 * log10(power))? Default TRUE.

Value

A list of class mrpheus_spectrogram with:

power: Numeric matrix. Rows = epochs, columns = frequency bins.
freqs: Numeric vector. Frequency bin centres (Hz).
epochs: Integer vector. Epoch indices.
channel: Character. The channel label.
db: Logical. Whether power is in dB.