Displays a spectrogram of an input trace.

Author

Jan Benda

Version

1.0 (Feb 10, 2013)

The Spectrogram-RePro records data without writing out any stimulus and displays a spectrogram of an input trace. The RePro terminates after duration seconds. If duration is set to zero, the RePro keeps running infinitely. Recording can be interrupted any time by pressing the space key or starting a different RePro.

A powerspectrum is computed every step second on a width seconds long chunk of data. If step is set to zero, it is set to width. The powerspectrum is averaged over ffts that use specsize datapoints, overlap by half if overlap is true, and are windowed using the window function window.

The resulting spectrogram is displayed for the last tmax seconds. The default maximum frequency shown is fmax. The color code displays all values between pmin and pmax decibel of the maximum possible power in the spectrum. The maximum power is either set to the maximum power in each powerspectrum (powermax is set to true) or to the maximum possible power of the input trace range.

Options

• intrace=V-1: Input trace (string)
• width=100ms: Width of powerspectrum window (number)
• step=0ms: Temporal increment for powerspectrum window (number)
• tmax=10s: Maximum time to plot in spectrogram (number)
• duration=0s: Total duration of spectrogram (number)
• size=1024: Number of data points for FFT (string)
• overlap=true: Overlap FFT windows within single powerspectrum (boolean)
• window=Hanning: FFT window function (string)
• powermax=true: Power relative to maximum (boolean)
• fmax=2000Hz: Maximum frequency (number)
• pmax=0dB: Maximum power (number)
• pmin=-50dB: Minimum power (number)