Questions tagged [discrete-wavelet-transform]
The discrete-wavelet-transform tag has no usage guidance.
17
questions
2
votes
1answer
64 views
How could I do a Discrete Fourier Transform in Python if my data is non uniform?
I have been trying to find a way to transform my time series data in an equivalent manner to the discrete Fourier transform. What I wish to find is something like:
...
1
vote
1answer
49 views
What exactly is meant by "translation invariant dictionaries/wavelets"?
I'm trying to wrap my head around the notion of translation invariance in terms of dictionaries/wavelets. For example in Lecture Notes, Page 41 its written that one starts with a family of atoms/...
0
votes
0answers
14 views
Inverse discrete wavelet transfrom
I am trying to understand the formula of the inverse wavelet transform. Although I have looked at many papers none of them fully define the summations that appear and this is creating a lot of ...
2
votes
3answers
180 views
Continuous Wavelet Transform vs Discrete Wavelet Transform
The discrete wavelet transform is applied in many areas, such as signal compression, since it is easy to compute. I notice that, However, the continuous wavelet transform (CWT) is also applied to ...
0
votes
0answers
27 views
Extract signals with certain frequenceis from a data sample using python
I did not major in signal processing, and I do not know a lot about some possibly very basic facts, so although SE has some questions related to this, I still have some confusion.
I am given a data ...
0
votes
0answers
27 views
Problem with creating wavelet transform
I am trying to create time-frequency representation of my brain signal. I would like to create the data for frequencies from 0hz - 120hz (so it can cover, delta, theta, alpha, beta, low-gamma and high-...
2
votes
3answers
53 views
What does the intensity values on wavelet transform mean? Amplitude or power?
So when applying wavelet transform, we get a 2d plot. Each point in that 2d plot has a color, showing intensity of something. But I cannot understand if it is an amplitude or power?
1
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0answers
82 views
How to find the Wavelet measurement matrix in compressed sensing?
Assume that an image vector x = Ψs. s is a sparse vector in which the image vector x of length N x 1 is sparse in the wavelet Ψ basis.
I have issue in finding the measurement matrix A= φ Ψ where φ is ...
1
vote
1answer
83 views
Waveform pattern detection in time series
I have some IMU data which I am using to detect activity patterns - walking, running etc.
In order to differentiate one activity from another I need to do pattern matching in time series. Different ...
0
votes
0answers
27 views
Wavelet, scaling, detail, and smooth/approximation coefficients
I was reading through the documentation for the R wavelets package and doing a little experimentation and noticed that the modwt ...
0
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0answers
159 views
PyWavelets SWT versus MODWT
I'm just learning about wavelets and the PyWavelets package. I saw a reference to MODWT, which led me to the SO post here and then to this Python package: https://github.com/pistonly/modwtpy
What ...
0
votes
0answers
58 views
Regarding custom wavelets and their validity
I've recently started working with wavelets, and want to focus primarily on Discrete Wavelet Transform. For experimental purposes, I use the PyWavelets library in Python. In one of my tests, I tried ...
0
votes
0answers
12 views
Discrete Wavelet Transform Time Series
My problem is to cluster some time series together. But due to a huge length I was interested in using some methods to reduce the dimensionality. I was thinking of Discrete Wavelet Transform since the ...
1
vote
0answers
31 views
Pros/Cons to using Spectral and Diffusive Graph Wavelets
As I understand, there are two major methods of constructing wavelets on graphs. Spectral wavelets, from David K Hammond et. al, and diffusive wavelets from Coifman and Maggioni. I can't quite parse ...
2
votes
0answers
30 views
What does the sample entropy of a digital signal mean?
What sample entropy signifies about a signal and how it used to analyse a signal?
1
vote
1answer
46 views
Why discrete wavelet transforms use sampling rate 2 and need signal length to be a power of 2?
I know Fourier transforms but new to wavelet transforms. I can understand Haar transform needs signal length a power of 2, since the filters have 2 taps and down-sampling and up-sampling in the ...
1
vote
1answer
34 views
Does the Fast Wavelet Transform produce the same coefficient as the Discrete Wavelet Transform?
Does the Fast Wavelet Transform(FWT) produce the same coefficients as the Discrete Wavelet Transform(DWT) if configured for the same depths? Or is the the FWT just an approximation of the DWT?
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