Linked Questions

22 votes
2 answers

Synchrosqueezing Wavelet Transform explanation?

How does Synchrosqueezing Wavelet Transform work, intuitively? What does the "synchrosqueezed" part do, and how is it different from simply the (continuous) Wavelet Transform?
OverLordGoldDragon's user avatar
5 votes
4 answers

Why are there beats in spectrogram / Windowed Fourier Transform of sines?

I am trying to understand how the Windowed Fourier transform works, so I used Matlab to create an artificial signal, and plotted the Windowed Fourier transform using a gaussian window. $x(t) = \left\...
meta_warrior's user avatar
4 votes
3 answers

Why Hilbert Transform is terrible choice for amplitude demodulation of broadband signals?

A reference answer empirically demonstrates that Hilbert envelope does not work well for the (amplitude) demodulation of a broadband signal. I am looking for the math which explains why...
Gideon Genadi Kogan's user avatar
3 votes
3 answers

Difference between librosa.stft and scipy.signal.stft

I read the source code of librosa.stft and sicpy.signal.stft, and notice that the calculation results of STFT in these two libraries are quite different: In scipy.signal.stft, the stft result is ...
Xiong's user avatar
  • 41
6 votes
3 answers

Role of window length and overlap in uncertainty principle?

I am trying to predict epilepsy using spectrograms and a convolutional neural network. So far I have achieved a validation accuracy of 86% which i feel like is pretty good. Lots of the papers doing ...
niklas Munkholm Hjort's user avatar
6 votes
1 answer

Equivalence between "windowed Fourier transform" and STFT as convolutions/filtering

I've heard, that "windowed Fourier transform" is but one perspective on STFT, and that STFT is fundamentally convolutions of windowed complex sinusoids with the input, i.e. bandpass ...
OverLordGoldDragon's user avatar
0 votes
1 answer

Converting from PSD (V^2/Hz) to dBV (1 Volt RMS reference)

I'm having difficulty figuring out how to convert from PSD (V^2/Hz) to dBV (1 Volt RMS reference). The goal is to have a 1 Volt RMS input show as 0 dBV. Essentially I calculated the PSD of a signal ...
Michael Joseph's user avatar
2 votes
2 answers

One integral inverse CWT

MATLAB's icwt docs state inversion to be done by a single integral: $$ f(t) = 2 \Re e\left\{ \frac{1}{C_{\psi, \delta}} \int_0^\infty \left< f(t), \psi(t) \right> \frac{da}{a} \tag{1} \...
OverLordGoldDragon's user avatar
2 votes
2 answers

FFT of 2 sine tones using windowing and zero padding. Wrong FFT amplitude

Here is my attempt to perform an FFT on a random signal with 2 tones in which I applied zero padding AFTER windowing. (I did not apply zero padding before windowing because that would suggest that the ...
shoggananna's user avatar
2 votes
1 answer

Correct Windowing Effect at Amplitude Scale

I am trying verify the noise floor returned by Matlab sinad(). I am able to get the results matching by summing power spectrum density with $\frac{f_\text{s}}{N}$. ...
John L's user avatar
  • 21
1 vote
1 answer

FFTs, Spectrograms, and Units

I am new to signal processing and I have likely a very easy question but I have found inconsistent answers everywhere. When performing an FFT, does it matter what units the amplitude is in? Currently ...
SirVoos's user avatar
  • 11
1 vote
0 answers

Amplitude and phase from variational mode decomposition?

If a VMD analysis were fairly successful, in the sense that the spectrum is unimodal and relatively sparse, but still with a bit of bandwidth is it possible to extract a meaningful local amplitude and ...
Eli S's user avatar
  • 131