instfreqplot(f,op1,op2, ... ); instfreqplot(f,fs,op1,op2, ... );
instfreqplot(f) plots the instantaneous frequency of f using a dgt.
instfreqplot(f,fs) does the same for a signal with sampling rate fs Hz.
The instantaneous frequency contains extreme spikes in regions where the spectrogram is close to zero. These points are usually uninteresting and destroy the visibility of the plot. Use the 'thr' or 'clim' or 'climsym' options (see below) to remove these points.
An example:
instfreqplot(greasy,16000,'thr',.03,'climsym',100);
will produce a nice instantaneous frequency plot of the greasy signal.
instfreqplot accepts the following optional arguments:
| 'tfr',v | Set the ratio of frequency resolution to time resolution. A value \(v=1\) is the default. Setting \(v>1\) will give better frequency resolution at the expense of a worse time resolution. A value of \(0<v<1\) will do the opposite. |
| 'wlen',s | Window length. Specifies the length of the window measured in samples. See help of pgauss on the exact details of the window length. |
| 'thr',r | Keep the coefficients with a magnitude larger than r times the largest magnitude. Set the instantaneous frequency of the rest of the coefficients to zero |
| 'nf' | Display negative frequencies, with the zero-frequency centered in the middle. For real signals, this will just mirror the upper half plane. This is standard for complex signals. |
| 'tc' | Time centering. Move the beginning of the signal to the middle of the plot. This is useful for visualizing the window functions of the toolbox. |
| 'image' | Use imagesc to display the spectrogram. This is the default. |
| 'dgt' | Use the 'dgt method to compute the instantaneous frequency. This is the default. |
| 'clim',clim | Use a colormap ranging from \(clim(1)\) to \(clim(2)\). These values are passed to imagesc. See the help on imagesc. |
| 'climsym',cval | Use a colormap ranging from \(-cval\) to \(cval\) |
| 'fmax',y | Display y as the highest frequency. |