Questions on the wavelet analysis functions of Mathematica.

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4
votes
3answers
659 views

Signal processing by means of WaveletTransform

I updated my question to explain what I want. I have the voltage-time curve from the real industial object. This curve was gotten from the digital oscilloscope: As you can see it has ...
1
vote
1answer
143 views

Is wavelet a Nonlinear transform, or Not? [closed]

Is wavelet a Nonlinear transform, or Not? specifically, continuous wavelet transform with morlet function. I am studying behavior of a dynamic system, and it has nonlinear behaviour. can I employ ...
10
votes
1answer
214 views

Wavelet transform order problem

I have a signal that I'm trying to study its time-frequency features by continuous wavelet transform. By choosing different wavelet order, I get some differences in the results. ...
3
votes
2answers
229 views

How to increase Spectrogram resolution?

I have a time-domain signal that I want do a time-frequency analysis on it. When I tried the Spectrogram, I always get very low resolution. For example: I have a ...
5
votes
1answer
383 views

Extracting information from the result of ContinuousWaveletTransform

I'm trying to analysis a signal and identify some time-frequency information of it. For example, around which time the specific frequency arrives. It appears that Mathematica has very powerful wavelet ...
2
votes
1answer
633 views

Continuous wavelet transform with complex Morlet function

The complex Morlet function is defined as: $$Ψ(t,f_c,f_b)= \frac{1}{\sqrt[]{ \pi f_{b} } }\exp(-t^2/f_b)\exp(\jmath 2πf_ct)$$ where $f_b$ and $f_c$ are two important parameters in modifying the ...
11
votes
3answers
389 views

WaveletScalogram in polar coordinates

For given dataset data = Re[Zeta[1/2 + I Range[0, 100, 0.01]]]; It is nice that Mathematica can plot data in both Cartesian and Polar coordinates. ...
2
votes
1answer
160 views

Daubechies scaling function

In Mathematica in wavelet package with the following codes Phi[x_, j_, k_] := 2^(j/2) WaveletPhi[DaubechiesWavelet[3], 2^(j) x - k] Mathematica computes ...
2
votes
0answers
144 views

Is there a relatively easy way to add the “Cone of Influence” to a waveletscalogram?

I am analyzing time series data using the ContinousWaveletTransform function and plotting the results with WaveletScalogram. I ...
1
vote
1answer
197 views

Function definition and delayed assignment

I need to define the following function MyWavelet[n_]["PrimalLowpass", prec_ : MachinePrecision] := Table[(-1)^(j - 1) h[[2*n - j]], {j, 0, 2*n - 1}] which ...
3
votes
1answer
200 views

Wavelets: Relative error vs compression ratio

I need to plot the relative error vs compression ratio diagram of a discrete wavelet transform on an image, but no luck so far .. Here's the problem in short: random_image.jpg compress the image ...
15
votes
2answers
940 views

Detecting spikes by shrinking WaveletPacket basis using a specific threshold

Last time, I asked how I can use the command DiscreteWaveletPacketTransform[data, filter, 0] for spike detection and I got answers mostly based on an automatically ...
5
votes
2answers
682 views

Wavelet Packet Transform in Mathematica 7 and 8

For finding location of spikes in a time series I used to transform the data into wavelet space using DiscreteWaveletPacketTransform [ data, filter, 0] and then ...