# Questions tagged [signal-processing]

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

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73 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 ...
1k views

### high pass filter without losing detail

I have troubles doing a simple high pass filtering... Downloading the test data https://pastebin.com/74J8t2YV as "test.dat", you can see that overimposed on the signal there are some low frequencies ...
105 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 $9\times 2$ ...
75 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 ...
148 views

### Computing FundamentalFrequency

How does Mathematica use AudioLocalMeasurements to compute the fundamental frequency? Is there any formula? I can't seem to find what method Mathematica makes use ...
564 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?
110 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 ...
64 views

### Creating time varying 2d coordinates with OrnsteinUhlenbeckProcess

I see that I can create time varying 1d data with e.g. ...
182 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 ...
119 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 ...
200 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 ...
380 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(...
114 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: ...
144 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 ...
173 views

### Comparison of Continuous and discrete Fourier Transform

Consider a continuous signal as follows: ...
67 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: ...
554 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 ...
190 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 ...
105 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: ...
133 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 ...
102 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: ...
334 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 ...
746 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 ...
861 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 ...
212 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, <...
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 (...
142 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 ...
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 ...
290 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:
280 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 ...
71 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 ...
296 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....
777 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: ...
225 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 ...
181 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 : ...
405 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 ...
756 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 ...
205 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 ...
124 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 ...
320 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 ...
89 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 ...
107 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 ...
197 views

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

Due to ContinuousWaveletTransform[...] I can obtain information about wavelet-coefficient for example ...
782 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 ...
139 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 ...
309 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 ...
345 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:...
692 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 ...
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 & ...