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Questions tagged [signal-processing]

Digital signal processing of sound, video or other single or multidimensional data

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1answer
99 views

How to get exact frequencies in the time response using InverseFourier?

I have amplitude data varying with frequency for a signal. From that I want to generate time response in such a way so that if I take Fourier I can get the ...
15
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0answers
328 views

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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0answers
1k views

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....
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0answers
292 views

Resources for Sound Synthesis & Design

Are there any resources for sound synthesis using Mathematica? This page, Mathematica: Audio Synthesis Software, refers to other software packages, e.g. Max/MSP and Csound, for real-time synthesis. ...
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0answers
58 views

GaussianMatrix algorithm details

GaussianMatrix[] supports a Method -> "Bessel" option which the documentation describes (in the Details section) as: With ...
5
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0answers
164 views

Comparison of Continuous and discrete Fourier Transform

Consider a continuous signal as follows: ...
4
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0answers
326 views

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:...
4
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0answers
703 views

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 ...
4
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0answers
75 views

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 <...
4
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0answers
495 views

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 ...
4
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0answers
390 views

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 ...
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0answers
354 views

Bandpassing EEG's using Mathematica's Bandpass Function

Let's say we have an EEG signal approximated using a fractional Brownian motion: ...
3
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0answers
169 views

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,...
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0answers
103 views

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 $\...
3
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0answers
278 views

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 ...
3
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0answers
177 views

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 : ...
3
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0answers
256 views

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 ...
3
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0answers
56 views

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. ...
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0answers
46 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 <...
2
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0answers
56 views

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 ...
2
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0answers
158 views

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 ...
2
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0answers
100 views

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 $9\times 2$ ...
2
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0answers
198 views

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 ...
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0answers
39 views

Implementing an anti-alliasing filter in Mathematica

I'm experimenting with FFT simulations. I'm generating transient data at the some sampling rate, down-sampling this (mimicking a device's behavior) to 2048 points. Then take the FFT using ...
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0answers
66 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 ...
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0answers
39 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}) $:- ...
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0answers
29 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: ...
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0answers
99 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 ...
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0answers
104 views

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 ...
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0answers
109 views

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 ...
1
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0answers
128 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 ...
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0answers
152 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 ...
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0answers
401 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 ...
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0answers
836 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 ...
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0answers
53 views

Butterworth single pole, 5 Hz cut-off frequency on accelerometer data for single axis

I have read other posts here on using the Butterworth filter in Mathematica, however, I am having a hard time understanding the chain of functions and their parameters as applied to my case, and I am ...
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0answers
85 views

Fourier Scaling Issue

First a little background: I’ve looked at the following discussions on StackExchange and still racking my head on Fourier What are the most common pitfalls awaiting new users? Discrepancy between ...
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0answers
49 views

Is there a complex version of PeriodogramArray?

I am trying to build some functions to help me work with audio data collected as time streams but converted to the frequency domain. The frequency domain results must be complex because phase is ...
0
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0answers
54 views

Prevent running out of memory when doing SpectrogramArray?

I was using SpectrogramArray[Import@"myFile", 22050, 22050]to transfrom a piano mp3 file so that I can (probably?) generate a midi file from that mp3. The step size ...
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0answers
70 views

LowpassFilter and LeastSquaresFilterKernel implementation

I'm in the troublesome phase to port Mathematica code into another programming language. I cannot find a proper reference on the algorithm used in the ...
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0answers
73 views

Numerical error or mistake when filtering using Fourier?

I am comparing the filtering method using a recurrence filter with filtering using Fourier. I think both methods should give the same answer but they differ by a small amount that could be numerical ...
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0answers
103 views

How can I express chains of filters using recurrence relations?

Here's example of what I would typically do in Python to play around with system of custom filters: ...
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0answers
306 views

Engineering spectral densities using filtered white noise

My goal is to create time-spectrum noise signals with spectral densities $S_{xx}(f)$ for pretty much arbitrary spectral densities (think white noise, lorentzian, $1/f$). In finding advice on how to do ...
0
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0answers
205 views

How does KalmanEstimator update the Kalman gain, process noise and state variable mean?

The first "Application" in the documentation for KalmanEstimator is copied below with additional variables for clarity. ...