# Wayne King

### MathWorks

I am a developer on the Wavelet Toolbox at MathWorks

DISCLAIMER: Any advice or opinions posted here are my own, and in no way reflect that of MathWorks.

Professional Interests: Signal Processing

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**Content Feed**

Understanding CWT Morlet: Time and frequency resolution

Hi SungJo, the analytic Morlet wavelet used in the cwt() function and cwtfilterbank as 'amor' is defined in the frequency domain...

mer än ett år ago | 0

| accepted

analytical expression for Morse wavelet

Morse wavelets are defined in the frequency domain, so the analytic expressions for the Morse wavelets involve an integral. Obvi...

mer än ett år ago | 1

How do I switch from Level to Frequency when performing discrete wavelet transforms?

Hi, The discrete wavelet transform divides the signal energy into octave bands. So the wavelet filtering at level J, approximate...

mer än ett år ago | 1

How to plot scalogram in time period?

Hi Jan, you can do the following: Fs = 1e3; t = 0:1/Fs:1; x = cos(2*pi*32*t).*(t>=0.1 & t<0.3)+sin(2*pi*64*t).*(t>0.7); wgnN...

mer än ett år ago | 1

How to plot scalogram in time period?

Hi Jan, can you try surf() instead of imagesc()? Alternatively, can you attach a sample time series along with the necessary inf...

mer än ett år ago | 1

How to plot scalogram in time period?

Hi Jan, you do not mention the release you are using, but you can put the data in a timetable with the RowTimes equal to whateve...

mer än ett år ago | 1

| accepted

Extract signal components from mixed signal

Hi Sohel, for the given frequencies and signal lengths, the spectra of I_second and I_third are not delta functions in frequency...

nästan 2 år ago | 0

Extract signal components from mixed signal

Hi Sohel, May I first suggest that you clean this code up a bit. It isn't easy to follow exactly what kind of signals you are cr...

nästan 2 år ago | 2

| accepted

How to reconstruct a signal from it's Wavelet transform using Mexican Hat wavelet

This is not a bug. When you make the call: coefs=cwt(X,0.001:100,'mexh'); You are calling the legacy CWT() interface which is ...

ungefär 3 år ago | 1

| accepted

Old version and new version of CWT(Continuous Wavelet transform) to detect abrupt change in signal

Supatat, You are free to use the old CWT API if you wish. However, we recommend the newer API for reasons I've tried to explain ...

ungefär 3 år ago | 0

| accepted

The difference between the old version and new version of CWT (Continuous Wavelet Transform)

Hi Supatat, Some of this has been discussed here: https://www.mathworks.com/matlabcentral/answers/474889-why-the-old-version-...

ungefär 3 år ago | 1

| accepted

how to do wavelet transformation in real time?

Hi are you using dsp.DyadicAnalysisFilterBank? In that case the input signal must be a multiple of four along its first dimensio...

mer än 3 år ago | 0

bug in cwt function

Hi Ziba, First of all, I would encourage you to use the new CWT interface as opposed to the legacy interface you are using here....

mer än 4 år ago | 0

Continuous Wavelet Analysis without COI

Hi Evan, the CWT outputs everything you need to do the plot with the cone of influence. For example: load kobe; % The...

mer än 4 år ago | 2

How does modwpt details provide zero phase filtering ?

MODWPTDETAILS actually projects the signal onto the various wavelet packet subspaces, that is what provides the zero-phase filte...

mer än 4 år ago | 0

Unable to open openExample('wavelet/XpwWaveletMLExample')

That example is part of MATLAB R2018a. The example was not shipped with the R2016a version of MATLAB.

mer än 4 år ago | 0

| accepted

Additional wavelets that can be used in 2D CWT?

Hi Michael, in order to use a wavelet in CWTFT2, we need to have the expression for the Fourier transform of the wavelet. The wa...

ungefär 5 år ago | 1

| accepted

About using cwt function

Hi Alexander, For the CWT, the scaling functions are not commonly used. For discrete analysis wavelets are typically defined in ...

ungefär 5 år ago | 0

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About decimation in DWT

Hi Alexander, I don't think there is a trick here. The filter responses scale as you go down in resolution but that is becau...

ungefär 5 år ago | 0

About decimation in DWT

Hi Alexander, # Yes, you are correct that the downsampling causes aliasing (or can cause aliasing). However, the analysis fil...

ungefär 5 år ago | 0

how does Wenergy for 1-D wavelet decomposition works???

Hi Alef, the Ed output gives the percentage of energy captured by the detail (wavelet) coefficients at each level, while the Ea ...

ungefär 5 år ago | 0

| accepted

Unable to change data from row to column by using transpose

Is the data in your workspace in the form of a MATLAB table? What does the >>whos command print out in your workspace? o...

mer än 5 år ago | 0

| accepted

How to perform 2 level dwt without using dwt2 wavelet?

Use wavedec2() that allows you to specify the level.

mer än 5 år ago | 0

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what is the scaling function on wavelet in the matlab?

Hi Mohammad, I'm not sure this question is complete since you just wrote "1" in the body. The scaling function provides the low ...

mer än 5 år ago | 0

error msg- Input must contain only finite real nonnegative integers. when using coif1.3 and bior1.3 in place of haar

Hi Naval, I agree with Walter that we need more information. It helps to give us some sample data that we can reproduce the issu...

mer än 5 år ago | 1

any body please explain me what is happening in swt command in matlab? swt in the sense stationary wavelet transform.

Hi Bharat, Have you read the literature on the stationary wavelet transform? This is the paper to read: <https://people.maths.b...

mer än 5 år ago | 0

cwt.m normalization

Hi Simon, that energy normalization should be interpreted here in the correct way. With the CWT, we don't preserve the energy in...

mer än 5 år ago | 1

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cwt.m normalization

Hi Simon, the scalogram is normalized for the L1 norm already. In many other uses of the wavelet transform, it is customary to n...

mer än 5 år ago | 1

How to do inverse continuous wavelet transform from sym8 wavelet domain

Hi Rubio, Why would you want to do this? The CWT should be obtained at multiple scales and those scales should be logarithmicall...

mer än 5 år ago | 1

how can I detect R-peak using DWT(db2 or db3)?

Hi Neal, there are many different techniques for this using wavelets. Here is a simple example: http://www.mathworks.com/help...

mer än 5 år ago | 0