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

learn more… | top users | synonyms

3
votes
0answers
77 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 : ...
0
votes
2answers
66 views

Applying a window over a list

The window functions state that they tread over lists, but when I try to do: HammingWindow/@list, I do not get the expected results. What is the best way to apply a window over an arbitrary length ...
2
votes
0answers
31 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 ...
0
votes
1answer
80 views

Problem with Sin and ListPlot

In order to produce a smooth sine wave (Sin) and visualize it (ListPlot), I seem to need a very high sample rate (much higher than Nyquist). I want to know if this is a artifact of ListPlot or Sin ...
1
vote
2answers
82 views

Plotting amplitude spectra of modulated message signal

I'm trying to plot the amplitude spectrum of the modulated message signal, I have managed to plot it by working through the maths, expanding out each trig function, and then drawing onto a graph ...
1
vote
1answer
58 views

Why there is a click sound when I play a sound?

When I consider this simple code: ListPlay[RandomReal[1, {2000}], SampleRate -> 1000] I hear a click at the beginning of the sound sample and at the end of ...
1
vote
0answers
72 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 ...
1
vote
0answers
91 views

Wavelet Data Visualization (modus and phase) ListPlot [closed]

Due to ContinuousWaveletTransform[...] I can obtain information about wavelet-coefficient for example ...
3
votes
1answer
96 views

Getting correct amplitudes with Periodogram

I'm having some trouble with the function Periodogram, mainly with getting it to produce correct amplitudes for the spectrum it returns. My question is how to fix ...
1
vote
0answers
77 views

Is oscillation seen in data signal or noise? [closed]

I have some experimental data which is well-fitted by 40 terms of a Fourier series. I want to know if the oscillation exhibited is signal or noise. I evaluated the code shown below to plot my data in ...
0
votes
0answers
61 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 ...
1
vote
0answers
60 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 ...
11
votes
1answer
192 views

Extracting signal from gaussian noise

I am trying to extract a signal, $X$, from a noisy source of data, $Z$: $Z = X + Y$ where I know that $Y\sim N(0,\sigma)$, and I know the standard deviation $\sigma$. I am starting with a surrogate ...
2
votes
3answers
263 views

Using BandpassFilter

https://drive.google.com/file/d/0B7G3oUuZG1TwRHNNV1RFZjFWUXM/view?usp=sharing Above I have linked a data set containing a 2 seconds EEG sample I have recorded of someone "blinking". This data set was ...
6
votes
6answers
256 views

How do I build a patterned matrix (high-pass and/or low-pass filter bank)?

I would like the shortest code to build the following matrices, of arbitrary dimension $N$: A Low-Pass filter bank matrix is of the form $ \begin{bmatrix} 1 & 1 & 0 & ...
1
vote
2answers
93 views

How to obtain the magnitude with dB in DFT?

I want to do a DFT of a fragment of music,and then plot the magnitude with dB instead of amplitude. For example: ...
5
votes
1answer
186 views

How to fit data to a convolution equation

How to fit data to a convolution equation: ...
0
votes
1answer
96 views

Phase spectrum of a linear chirped signal

I am calculating the phase spectrum of a linear chirped signal. I actually don't know how the phase spectrum should be, but I would expect something in the range of interest (the bandwidth) at least ...
5
votes
3answers
239 views

Find when two lists are parallel with autocorrelation

I am working on a signal processing project with two oscillators. The first oscillator has a frequency $f_1$ that is independent, and the second oscillator has a frequency $f_2$ that increases, and ...
0
votes
0answers
55 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 ...
11
votes
1answer
273 views

How can I use Mathematica to numerically compute a Wigner spectrogram of an optical pulse?

This question was inspired by this question where it is necessary to numerically compute the Fourier transform of a Gaussian optical pulse with a Gaussian chirp function. $$E(t)=e^{-t^2} \cos(50 t - ...
2
votes
1answer
69 views

Digital filter. Why do these two methods produce such different results?

I am trying to produce a transfer function with a peak=3000 and gain=1 first order on the high pass side and second order on the low pass side. I believe the below two methods should produce ...
3
votes
2answers
144 views

How can I filter this signal in mathematica

Given the transfer function $H(z) = \frac{1}{4}(1+z^{-1}+z^{-2}+z^{-3})$ and the input signal $x[n] = \cos(\frac{\pi}{50}n)+\cos(\frac{4\pi}{5}n)$, how can I find the output signal $y[n]$ in ...
2
votes
1answer
163 views

How can I convert a Sound created with SoundNote to a list of samples?

I have a Sound created with SoundNote, as follows: simpleSound = Sound[SoundNote["C"]] ...
0
votes
0answers
94 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 ...
3
votes
0answers
77 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 ...
-1
votes
1answer
64 views

Mathematica nested loops [closed]

I can write down the following Python code: for j1 > 2: time1 = i1 for i2 > i1: if j2 < 2: time2 = i2 break Purpose of the above code: ...
3
votes
0answers
196 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 ...
0
votes
0answers
36 views

1D phase unwrapping [duplicate]

I want to unwrap a signal but I don't know where to add the 2 Pi. How should I unwrap the phase? ...
1
vote
0answers
343 views

How to compute the Power Spectral Density of an EEG signal [closed]

I have an EEG signal of length N on a given channel (FP1). I would like to compute the power spectral density of the signal. More specifically, once the PSD is computed, I would like to sum the ...
0
votes
0answers
84 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. ...
2
votes
0answers
68 views

We need to know the input signal when we use KalmanEstimator?

The first "Application" in the documentation for KalmanEstimator is copied below with additional variables for clarity. ...
4
votes
0answers
54 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 ...
3
votes
0answers
51 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. ...
7
votes
1answer
180 views

Why the BandpassFilter is different than applying LowpassFilter then HighpassFilter

If I generate some data with noise, and use a filter to filter the noise, why does BandpassFilter not produce the same results as using ...
6
votes
1answer
294 views

How to make sense of LowpassFilter, SampleRate and the cutoff frequency ωc in different Mathematica versions?

How do you make sense of the scale of "time" and "sampling" when using LowpassFilter and SampleRate ? Given the test data with ...
7
votes
1answer
398 views

How to extract notes and chords from audio?

I have a 3-second recording of a guitar chord which you can safely download here. I'm trying to use Mathematica's wavelet features to find out the notes in the chord, at least the docs says that ...
3
votes
0answers
164 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 ...
0
votes
1answer
79 views

How to find the starting point of an oscillation (with noise)?

I've got a series of coordinates which start to oscillate from some time (and with noise), like this: ...
0
votes
1answer
162 views

Are there any open source projects related to signal processing

I am going to make a program related to audio signal processing . Are there any open source projects related to it?
1
vote
0answers
60 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 ...
14
votes
4answers
673 views

Cross-Correlation with TimeSeries

How to find hidden relationship between two TimeSeries data sets? I normally compute the Cross-Correlation function, but I cannot find an easy way of doing this on the TimeSeries objects in ...
1
vote
1answer
222 views

Extracting out the Fourier modes of a series, and using these to reconstruct data series

I would like to extract the most important frequency modes from a data set which exhibits strong annual periodicity, as well as some (less) important shorter-term frequency components. The following ...
5
votes
0answers
456 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 ...
7
votes
2answers
386 views

Building Butterworth Bandpass Filters

In order to bandpass filter data it is necessary to use ButterworthFilterModel, followed by ToDiscreteTimeModel and RecurrenceFilter. I have two questions: I wish to specify the order of the ...
1
vote
0answers
182 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 ...
2
votes
0answers
137 views

Position from 3 dimensional acceleration data? [closed]

Per a previous post on Mathematica StackExchange here I'm trying to utilize 3-axis accelerometer data to determine approximate 3D position. I wanted to start with a simple case. To this end I've ...
2
votes
1answer
314 views

Is there any function in Wolfram Mathematica simmilar to fft.fftfreq (Python)

Here is an explanation of fft.fftfreq I have data with random noise: ...
4
votes
2answers
340 views

FindPeaks does not smooth noise on peak?

I have experimental data which is noisy. My objective is to find the peaks. Here is a short part of the data. ...
3
votes
2answers
155 views

Compare two shifted signals

I have one set of original data (signal A) and a second set of derived data (signal B) which was computed from A by position rotation (circular shift). Here are the data for the signals (A and B): ...