Scaled Time-Frequency Distribution using Morlet-Wavelets
"Multiscale TFD" computes a time-frequency distribution of an input
signal x within a given frequency interval as a sequence of
short-time spectra of windowed signal segments, the length of each
one inversely proportional to the frequency.
This function yields a 2D signal output of the scaled time-frequency
distribution displaying time (x-axis) versus frequency (y-axis) with
the power or amplitude spectral values given on the z-axis.
"Multiscale TFD" needs the following parameters:
Note: The type of Fast Fourier Transform and the window type applied
implicitly can be adjusted in the Basic Options menu under
- lower frequency f0 (in reciprocal x-axis units),
- upper frequency f1 (in reciprocal x-axis units),
- fres, which is the output resolution (i.e. number of points)
of the frequency axis,
- tres, which is the output resolution (i.e. number of points)
of the time axis,
- convolution window size N as number of periods (note that the absolute
window size depends on the frequency),
- spectrum type (spectype), which is either
- "Power" (0) or
- "Amplitude" (1)
- type of normalisation (normtype), which is either
- "Absolute Power/Amplitude" (0),
- "Spectral Density" (1) or
- "Maximum Norm" (2).
signal x, y;
float f0, f1;
int fres, tres, N;
option spectype, normtype;
The result y is a 2D signal.
Momentary ARMA spectrum, STFT.
Akselrod/Keselbrener , Vandenhouten