Questions tagged [signal-processing]
Digital signal processing of sound, video or other single or multidimensional data
63 questions with no upvoted or accepted answers
19
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Strategies to find curves on messy data using FindCurvePath
I have a set of data points that correspond to roots of a transcendental equation with respect to a parameter (the abscissa) which, by the properties of the system, define continuous curves (might be ...
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7
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0
answers
2k
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Wavelet Transform Modulus Maxima (WTMM) method
Has anyone already coded the Wavelet Transform Modulus Maxima (WTMM) method for computing the singular spectrum using multi fractal formalism in Mathematica?
The goal is to analyse 1D, 2D and 3D data....
- 2,918
6
votes
0
answers
80
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GaussianMatrix algorithm details
GaussianMatrix[] supports a Method -> "Bessel" option which the documentation describes (in the Details section) as:
With ...
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5
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0
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158
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How to train each layer in a Neural Network so they optimize different loss functions in an adversarial network?
Example NetGraph to illustrate the idea (Input is an online signal with a value between -1 and 1, Noise is Gaussian Centered at 0 and standard deviation 0.1, EvilNet is constrained to output a value ...
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5
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0
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301
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Comparison of Continuous and discrete Fourier Transform
Consider a continuous signal as follows:
...
- 3,405
5
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1k
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Estimating Power Spectral Density from Autocorrelation
I have been tasked with computing the power spectrum of a noisy signal. Specifically, I am asked to do so through first attaining the autocorrelation function. From what I have read, the PSD is simply ...
- 121
4
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0
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195
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FIR filter and the relation between Sample rate and cut-off frequency
I have problem to unterstand the logic of the cut-off frequency of the FIR filter.
Suppose my sample rate is 2MHz and I want to design a lowpass filter with a cut-off frequency 100Hz. What will be $\...
4
votes
0
answers
718
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Constructing the spectral density of white noise
My goal is to find the spectral density $S_{XX}(f)$ from a time domain noise signal $X(t)$. The approach should work for general time series, but to illustrate what I've been doing I'll keep it simple:...
- 1,339
4
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0
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350
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Application of lowpass Butterworth filter
I'm trying to design a Butterworth lowpass filter with a cutoff frequency of
So far what I did is
...
- 387
4
votes
0
answers
97
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What does OutputResponse[sys, { {u1,u2,u3}, {v1,v2,v3} } ] do?
I am puzzled by the result of OutputResponse[sys, {{u1,u2,u3},{v1,v2,v3}}]. OutputResponse is used this way in the first "Application" in the documentation for <...
- 7,164
4
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0
answers
967
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Nonuniform Savitzky-Golay filter for smoothing and differentiation
The classical Savitzky-Golay filter works only with uniformly sampled data and currently we have at least two good implementations of it for Mathematica published on our site. But in many practical ...
- 62.3k
4
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0
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502
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Can Mathematica reconstruct an audio signal from a given spectrogram
I just realized that Mathematica can easily construct a spectrogram for a given .wav file. My question is, to what extent can this process be inverted in Mathematica?
Namely, lets say I have the ...
- 41
4
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0
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430
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Bandpassing EEG's using Mathematica's Bandpass Function
Let's say we have an EEG signal approximated using a fractional Brownian motion:
...
- 947
3
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0
answers
162
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How to reform a expression to improve numerical stability?
In engineering, we usually have to solve a function numerically, which has no symbolic computation ability and may using a low percision data type like fp32 or even ...
- 131
3
votes
0
answers
521
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Deconvolution using Fourier transforms
I have a 2D signal in the form of a function $g(x_m,y_m)$ given as
$$ \begin{aligned}
g(x_m,y_m) = \ & \int^{\infty}_{-\infty} \mathrm{d}x_o \ \mathrm{d}y_o \ \frac{1}{\varepsilon^2} P(x_o - x_m,...
- 371
3
votes
0
answers
471
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Whitening the data from the LIGO project
I'm following the official LIGO tutorial and I want to do a whitening process now. I computed FFT using hf=Fourier[data] then PSD using ...
- 41
3
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0
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249
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Filtering in frequency domain
I'm trying to modify a transfer function in the frequency domain by filtering it with a Butterworth filter.
For example, let's say my transfer function is of the form :
...
- 335
3
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0
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68
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What are all the elements of the expression returned by KalmanEstimator used for?
The first "Application" in the documentation for KalmanEstimator is copied below with additional variables for clarity.
...
- 7,164
2
votes
0
answers
113
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Finding recurrence relation from an inexact numerical sequence
Consider the recurrence relationship
d[0] = 0;
d[i_] := (1 + Sqrt[1 + 4 d[i - 1]^2])/2 /; i >= 1
which generates the following sequence (generated by using <...
- 489
2
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0
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99
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Sound steganography with `InverseSpectrogram`
Here is my code of how to hide a message inside a sound:
...
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2
votes
0
answers
104
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How can i use Butterworth filter written in matlab to Mathematica
i need help to convert this code written in matlab about Butterworth filter:
...
- 21
2
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0
answers
79
views
Create tone with adjustable frequency/amplitude
How can I play a tone and adjust its frequency and amplitude?
As an example, say I wanted to play a SquareWave with a slider for frequency and amplitude. Using a <...
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2
votes
0
answers
136
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Missing data - reconstructing large gaps with an autoregressive model
I am looking for a similar function as fillgaps in Matlab which helps to "replace missing samples in an otherwise uniformly sampled signal by fitting an autoregressive model to the samples surrounding ...
- 347
2
votes
0
answers
247
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Analysis of the periodic data by the maximum entropy method
I am trying to get the frequency spectrum of periodic data. Since the data set is short, the outcome of the frequency peaks are not sharp enough for me to do further analysis. I know the spectrum can ...
- 21
2
votes
0
answers
171
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Handling oscilloscope bitmap data
I'm using an oscilloscope from Tektronix; its output is formatted as a $n \times (m + 2)$ matrix, where $n$ is the number of vertical divisions and $m$ the temporal scale.
The first $9\times 2$ ...
- 361
2
votes
0
answers
395
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FindPeaks error " Expecting an image or graphics instead of"
I'm running Mathematica 10.3.1.0 on windows 7 Professional Sp.1 when I try to use FindPeaks I keep getting the following error, even when trying the example in the ...
- 33
2
votes
0
answers
920
views
Doing local FFT on huge 3D vector data cell mesh and visualizing it spatially?
Simulation type:
I'm running a simulation with the OOMMF micromagnetics package
http://math.nist.gov/oommf/
where are magnet is represented by a mesh of 3 million cells, it gets excited by a ...
- 247
1
vote
0
answers
173
views
How to Model a Parametric Fast Fourier Transform in Mathematica?
I'm using this code which evaluates the FFT of my original signal (which is a time series). Using the Manipulate function of Mathematica it is possible to vary the ...
1
vote
1
answer
196
views
Calculation of CIC/FIR filter is too slow
I'm investigating the propeties of Cascoded Integrator Comb (CIC) filter. (for sigma-delta modulator application). I have 2 quesitons and below is what I have done:
a). Any alternative method to ...
- 147
1
vote
0
answers
216
views
How to compute Total Harmonic Distortion (THD) for the following signal?
The signal is as follows
Sin[x - j]
with $j$ being
...
- 55
1
vote
0
answers
121
views
How to convolve two audio signal?
Can we obtain reverb effect by convolve two audio signal?
Here are some example.
https://www.bilibili.com/video/BV1vE411h7W2
- 11
1
vote
0
answers
76
views
SpectrogramArray timescale
I have a 600 second @ 8000 Hz WAV file which need to be analyzed in detail in terms of events (red parts in plot) defined in time and frequency that need to be rather exact, in particular the ...
- 115
1
vote
0
answers
70
views
Is there some programs about the fast inverse descrete time Fourier transform
At first, I give the definition of the inverse discrete-time Fourier transform
$$\phi(s)=\frac{1}{2\pi}\int_{-\pi}^{\pi}\exp(iks)f(k)dk$$
Here what I use is
...
- 173
1
vote
0
answers
34
views
What's the parameters of the Spectrogram function
The Spectrogram functions only has these parameters listed:
Spectrogram[list,n,d,wfun]
What's the value of the other ...
- 61
1
vote
0
answers
94
views
Plot Audio DAta
I am a beginner in mathematica.
Currently i am working on audio file my problem is when i extract audio information using BinaryReadList and try to plot it works with mono wav file but cannot get ...
- 31
1
vote
0
answers
89
views
How to filter audio to get best results in correlation?
I am trying to recognise the alphabetical letters by saving some data of records of me and others saying each letter, then comparing a test audio not contained in the data to each letter using the ...
1
vote
0
answers
88
views
Sound Processing frequency Dynamicly
Would like to know if there is a method to call upon the frequency of a song at a given time for instance at 0:34 second the frequency is x ;
But to do this live meaning as long as the song is ...
- 11
1
vote
0
answers
52
views
How to force the output to be in terms of a specific function?
I have a rectangular function rect[t], which is a window function with values of $ 1 $ in the interval $ (-\frac{1}{2},\frac{1}{2}) $:-
...
- 3,509
1
vote
0
answers
41
views
Error using ListCorrelate for Overhang parameters nonzero machine-sized integers
I've encountered a problem using the ListCorrelate function which I haven't been able to solve or find much information on.
Using the following code:
...
- 11
1
vote
0
answers
165
views
wavelet fourier transform
I want to do wavelet Fourier transform of my data but I have few doubts in this. 1)first of all what is octive and voice command here when i am changing value according to that my plot is changing but ...
- 11
1
vote
0
answers
123
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Mapping the MATLAB SP Toolbox to Mathematica
We have some work and people where I am doing signal processing using the signal processing toolbox in MATLAB and it comes up how to translate one or another of the large number of functions in that ...
- 4,102
1
vote
0
answers
133
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ButterworthFilterModel consumes the memory too much
I have a simple filter which is a result of the these questions here and here.
I have to use this filter in a Do loop but I found that this filter consume the ...
- 20k
1
vote
0
answers
151
views
Absurd solution by LinearSolve
I am trying to find curve that passes through all the data points.To do this i am doing interpolation using LinearSolve. No. of equations vary from 1000 to 3000.
LinearSolve gives me values of ...
- 41
1
vote
0
answers
228
views
PeriodogramArray or PowerSpectralDensity?
could anyone explain what is the difference between PowerSpectralDensity[data,omega] and PeriodogramArray[data]? When I plot them (starting from the same set of data of course) I get two different ...
- 11
1
vote
0
answers
524
views
Is there an equivalent of “pmtm” of MATLAB?
Recently I'm spending my time implementing some patients' analysis using Mathematica Classify function. But I need to rewrite some MATLAB functions for computing ...
- 11
1
vote
1
answer
354
views
Periodogram and frequency
On the x axis of periodogram, one should have either a period or frequency. What frequency is used in Periodogram --- angular or ...
- 4,036
0
votes
0
answers
79
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Reflected Wave and Power Spectrum for a Toda Oscillator
I'm trying to analyze the power spectrum of the reflected wave. Specifically, I want to compute the time series, take the Fourier transform, and average the absolute values to obtain the spectrum. The ...
0
votes
0
answers
115
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Comparing analytical and numerical results of 2D Fourier transform
I would like to be able to transform back and forth with Fourier and InverseFourier, however, I can't quite match up the results....
- 1,991
0
votes
0
answers
152
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How to extract data from wavelet scalogram?
I've read several topics here concerning wavelets.
Especially this one is very useful where in the answer is explained how to convert default Mathematica scalogram into useful one (with frequency and ...
- 29
0
votes
0
answers
75
views
Find knee by intersecting line method
I have an x-y data list. The data is here. It looks like below:
I want to mark the knee location. I mean I need to find the point of greatest slope change and get the x coordinate of this point. ...
- 199