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Questions tagged [signal-processing]

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

7
votes
1answer
531 views

How can I generate pink noise using Mathematica?

I need a time series of pink noise. How can I generate pink noise using Mathematica?
3
votes
1answer
107 views

Confused about the usage of AudioSpectralTransformation

The documentation for AudioSpectralTransformation says: AudioSpectralTransformation computes the short-time Fourier transform of audio, maps every value at ...
1
vote
1answer
63 views

Creating time varying 2d coordinates with OrnsteinUhlenbeckProcess

I see that I can create time varying 1d data with e.g. ...
2
votes
1answer
175 views

Implement inverse discrete-time Fourier transform

In Mathematica after version 9. We had ListFourierSequenceTransform to do discrete-time Fourier Transform, but we do not have the inverse function. If we peform it ...
1
vote
2answers
117 views

How to detect the singular value with wavelet analysis

I have a series data data=Uncompress[ FromCharacterCode[Flatten[ImageData[Import["http://i.stack.imgur.com/ApipY.png"], "Byte"]]]]; We can show it ...
6
votes
2answers
192 views

How to calculate the amount of offset about two list

You can get my data by this code {data1, data2} = Uncompress[FromCharacterCode@ Flatten[ImageData[Import["https://i.stack.imgur.com/ShSMY.png"], "Byte"]]]; We ...
2
votes
1answer
368 views

How to measure the pulse width in Plot Graph?

I'm practicing "Inverse Fourier transform" with impulse train using Diracdelta function. Condition Wavelength: 800(nm) Velocity of Lingt: 299,792,458(m/s) Using 1 and 2 >> Frequency0 = 299,792,458(...
0
votes
2answers
110 views

Can't get Mathematica to use FourierTransform in the way I want it to [closed]

I'm an EE working with signals and systems trying to get Mathematica to do a few basic functions to see if I could use it regularly in my work. Here's the code I'm working with: ...
1
vote
0answers
136 views

Manipulate Z-transform transfer function [closed]

I would like to express a Z-plane transfer function in a form of a difference equation so that I can implement it as an infinite impulse response filter. Here is an example of a continuous time ...
5
votes
0answers
164 views

Comparison of Continuous and discrete Fourier Transform

Consider a continuous signal as follows: ...
0
votes
1answer
66 views

Why am I getting unexpected result while implementing Fourier Transform?

I have considered five signals of different amplitude, frequency and phase components and applied Fourier Transform using the code given below: ...
3
votes
2answers
510 views

LowpassFilter Mathematica

I have this example signal: w1 = 3; (* rad/s *) w2 = 50; (* rad/s *) w3 = 4; (* rad/s *) signal[t_] = Sin[w1*t] + Sin[w2*t] - Sin[w3*t] I would filtrer this ...
3
votes
1answer
189 views

SAX implementation in Wolfram Mathematica

I have to deal with time series to find some patterns there. The method selected is SAX (based on PAA). There's a built-in function to convert a numeric times series into a series of letters with a ...
0
votes
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: ...
3
votes
0answers
132 views

Challenge: Calulating The Resulting 2D Image Behind A Lens [closed]

This is a tough question! I would like to calculate how an image (a real 2D photograph) looks if I place a lens at a certain distance d1 from it and I observe it at a certain distance d2. It is ...
1
vote
1answer
96 views

Sum and dump operation

I've looked a different Mathematica functions, and I don't find the following: sum and dump. It would be: ...
3
votes
1answer
329 views

Fourier Transform accelerogram seismic

I have a seismic accelerogram. I tried to apply the Fourier Transform to interpolate function, but dosn't work. So, i applied the ...
2
votes
1answer
718 views

Finding peaks on a Periodogram

I am currently working on a school project involving modelling sound recordings of piano notes. I have used the periodogram function to graph my recording and would like to find the peaks of this ...
7
votes
2answers
795 views

How to get a smooth derivative graphic

You can get data by this code: data = Normal[Databin["fHVr7FSi"]] Visualize it like following We can find some non derivable ...
4
votes
1answer
206 views

Applying filters to data of the form {{x1,y1},{x2,y2},…}

When working with any kind of measurement data there is (at least) for me always a phase where I have to play around with different filters (such as MedianFilter, <...
3
votes
3answers
3k views

How to do deconvolution in spectrum with some peaks?

For example, I have the next spectrum: I've seen the next question ["How to perform a multi-peak fitting?"][2] but not answer to my question. I want deconvolution the spectrum to obtain three peaks (...
4
votes
1answer
141 views

Experimental Data Overlay/Fit

I have two different sets of data represented in Contourplots: As you can see, in different positions of space, both have these very characteristic sets of four peaks (2 blue and 2 yellow). What I ...
32
votes
3answers
5k views

Remove noise from data

Hi, as you can see above I have some experimental data which has a large offset and shows clear noise fluctations around the tendency of the curve. I wanted to ask if someone could suggest me a method ...
8
votes
2answers
286 views

How to detect discolorations in an image?

I'm evaluating the technical quality of an images and I'd like to scan it for defects from dirty sensors. Are there any filters to quickly detect a blob of discoloration? Here are a few examples:
3
votes
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 ...
1
vote
0answers
69 views

GW150914 gravitational wave detection incident analysis [duplicate]

I'm analyzing the data from LIGO project, about first detection of gravitational waves. In one of the many threads here, someone said when I want to do an ASD of the strain I should use ...
0
votes
2answers
288 views

Power spectrum density calulation with ARProcess

I have a measurement of $x$ coordinates of an oscillating particle at presence of noise taken at constant time steps of 1/60 s. The corresponding data set can be obtained here: https://drive....
6
votes
5answers
760 views

Why isn't LowPassFilter working for these parameters?

First I define a function, just a sum of a few sin waves at different angular frequencies: ...
4
votes
1answer
220 views

Identify a note in a song using Mathematica

I'm trying to figure out how to use Mathematica to identify a note from a song. The short .mp3 file found here or here contains a bass-note that I'd like to identify. I can find it through ...
3
votes
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 : ...
0
votes
2answers
385 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 ...
8
votes
1answer
715 views

Finding outliers in 2D and 3D numerical data

I'm working on dataset which isn't normally distributed.which contains three dimensions like cost, discount and profit I'm trying to find outliers in all these dimensions. I used z score to find ...
2
votes
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 ...
2
votes
1answer
123 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
312 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
88 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
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 ...
1
vote
0answers
192 views

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

Due to ContinuousWaveletTransform[...] I can obtain information about wavelet-coefficient for example ...
4
votes
1answer
737 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
135 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
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 ...
4
votes
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:...
14
votes
1answer
661 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
481 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
619 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
345 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
430 views

How to fit data to a convolution equation

How to fit data to a convolution equation: ...
0
votes
1answer
292 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 ...
6
votes
3answers
326 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 ...
1
vote
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 ...