Least Asymmetric Wavelet and Phase

This example uses:

Open Live Script

Obtain the scaling filter associated with the symlet of order 4.

n = 4;
scal_sym = daubfactors(n,"sym");

Use the function freqz (Signal Processing Toolbox) to plot the frequency response of the filter. Compare the phase angle with a linear phase filter.

freqz(scal_sym)
subPlots = get(gcf,"Children");
phasePlot = subPlots(2);
yLimits = get(phasePlot,"Ylim");
hold(phasePlot,"on");
plot(phasePlot,[0 1],[0 yLimits(1)])
legend(phasePlot,"Symlet","Linear")
hold(phasePlot,"off")

Figure contains 2 axes objects. Axes object 1 with title Phase, xlabel Normalized Frequency (\times\pi rad/sample), ylabel Phase (degrees) contains 2 objects of type line. These objects represent Symlet, Linear. Axes object 2 with title Magnitude, xlabel Normalized Frequency (\times\pi rad/sample), ylabel Magnitude (dB) contains an object of type line.

Obtain the scaling filter associated with the Daubechies wavelet of order 4. Plot the frequency response of the filter. Compare the phase angle with a linear phase filter.

db_sym = daubfactors(n);

freqz(db_sym)
subPlots = get(gcf,"Children");
phasePlot = subPlots(2);
yLimits = get(phasePlot,"Ylim");
hold(phasePlot,"on");
plot(phasePlot,[0 1],[0 yLimits(1)])
legend(phasePlot,"Daubechies","Linear")
hold(phasePlot,"off")

Figure contains 2 axes objects. Axes object 1 with title Phase, xlabel Normalized Frequency (\times\pi rad/sample), ylabel Phase (degrees) contains 2 objects of type line. These objects represent Daubechies, Linear. Axes object 2 with title Magnitude, xlabel Normalized Frequency (\times\pi rad/sample), ylabel Magnitude (dB) contains an object of type line.

See Also

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