PHASEPLOT Phase plot
Usage: phaseplot(f,op1,op2, ... );
phaseplot(f,fs,op1,op2, ... );
PHASEPLOT(f) plots the phase of f using a DGT.
PHASEPLOT(f,fs) does the same for a signal with sampling rate fs Hz.
PHASEPLOT should only be used for short signals (shorter than the
resolution of the screen), as there will otherwise be some visual
aliasing, such that very fast changing areas will look very smooth.
PHASEPLOT always calculates the phase of the full time/frequency plane
(as opposed to SGRAM), and you therefore risk running out of memory
for long signals.
PHASEPLOT takes the following flags at the end of the line of input
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.
'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 usefull for visualizing the
window functions of the toolbox.
'thr',r Keep the coefficients with a magnitude larger than r times the
largest magnitude. Set the phase of the rest of the
coefficients to zero. This is useful, because for small
amplitude the phase values can be meaningless.
'timeinv' Display the phase as computed by a time-invariant
DGT. This is the default.
'freqinv' Display the phase as computed by a frequency-invariant
DGT.
'fmax',y Display y as the highest frequency.
'colorbar' Display the colorbar. This is the default.
'nocolorbar' Do not display the colorbar.
For the best result when using PHASEPLOT, use a circulant color
map, for instance hsv.
Examples:
---------
The following code shows the phaseplot of a
periodic, hyperbolic secant visualized using the hsv colormap:
phaseplot(psech(200),'tc','nf');
colormap(hsv);
The following phaseplot shows the phase of white, Gaussian noise:
phaseplot(randn(200,1));
colormap(hsv);
References:
R. Carmona, W. Hwang, and B. Torresani. Practical Time-Frequency
Analysis: continuous wavelet and Gabor transforms, with an
implementation in S, volume 9 of Wavelet Analysis and its Applications.
Academic Press, San Diego, 1998.
Url: http://ltfat.github.io/doc/gabor/phaseplot.html
See also: phaselock, demo_phaseplot.
Package: ltfat