# Questions tagged [cwt]

Continuous Wavelet Transform. Time-frequency localization method with a wavelet kernel correlating against signal across scales and translations. Is non-orthogonal and overcomplete (unlike Discrete WT), varies time & frequency resolution across scales (unlike STFT), and is invertible. Usage includes image compression, multi-resolution analysis, instantaneous frequency estimation, transient detection, feature extraction.

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### Morlet wavelet convolution

I use a simple formula (without normalization) from Mike Cohen's "Analzying neural time series data" book. \begin{align} \psi \left( t \right) &= e^{-\frac{t^2}{2 s^2}} \cdot e^{2 \...
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### How to implement scale-dependent Gaussian averaging using Morlet wavelet envelope in Python?

I'm trying to reproduce the scale-dependent Gaussian averaging of a time series as described in this paper: https://arxiv.org/pdf/1706.01126.pdf The process involves performing a continuous wavelet ...
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### Why no Daubechies wavelet from Continuous Wavelet Transform?

thank you for considering this question. Do you know any reason why Daubechies wavelet can't be used for Continuous Wavelet Transfrom, but only for Discrete Wavelet Transform ? Matlab toolbox and ...
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### ICWT filtering signal with a cut-off frequency

In ssqueezepy, by finding a certain scale is it possible to do an icwt only for the scales above (or bellow) ? For exemple if I have a double sin (with $f_1$ and $f_2$), by taking the frequency $f_c$ ...
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### Wavelet signal analysis approach for multi-mode, noisy signal

I have a signal that I am trying to analyze via Matlab's CWT functions. The signal has two distinct oscillating components and I would like to extract the decay factor from each of them. Here is what ...
1 vote
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### Python's equivalent of MATLAB's cwtfilterbank

I am learning signal processing and would like to know what's the python equivalent of matlab's cwtfilterbank. I looked through pywt but did not find anything. Some ...
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### Integrating CWT around nominal frequency with amplitude and phase

I have a real signal f sampled at 96Hz composed of clusters of harmonics scattered tigthly around evenly central frequencies close to 1Hz and 2Hz (multiples of 0.966Hz) that I'll call features. These ...
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### Inverse of wavelet transform modulus gives poor results

I just want to understand, why is the result of my wavelet(?) transform so bad. For $0\le i< k$, where I set $k$ to $10$, I split the signal in blocks of length $s_i:=2^{i+2}$, overlapping by $s/2$...
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### How best analyze a very short data record (~100 data points) windowing and padding data to perform CWT

I have short segments of a biological signal interpolated at 10 Hz (anywhre from about 8.5 sec to 10 sec length). I want to use a cwt to then convert this segment to frequency over the short time ...
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### Zeroing input frequencies to improve inverse CWT

This is a follow up of my previous question Why is inverse CWT inexact / inaccurate? Rephrasing its accepted answer in my own words: The filterbank's transfer function gives information on what band ...
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1 vote
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### Why is inverse CWT inexact / inaccurate?

I'm all new to wavelet analysis. I'm trying to get a working understanding of the continuous wavelet transform and its inverse. By "working understanding", I really mean "getting some ...
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### What do computed CWT frequencies and color values correspond to?

I wanted to make wavelet transform and represent the frequencies as function of time instead of the scale of the wavelet as function of time. This example that uses ...
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### 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/...
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### log(conv) vs conv(log)

Suppose an arbitrary, strictly positive $x[n]$, transformed as $$x_l[n] = \log(1 + C x[n]) \tag{0}$$ where $C$ is freely chosen. Given the following, where $h[n]$ is a Gaussian lowpass filter (or ...
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### 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 ...
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### Wavelet "center frequency" explanation? Relation to CWT scales?

I noticed that there are many ways to relate the scale factor of wavelets to some characteristic frequency, such as the peak frequency, the central instantaneous frequency, and so on(plz see section 2....
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