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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 ...
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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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2answers
257 views

How can I generate a sin wave with power law noise?

I am interested in simulating a signal with different types of power law noise, as entitled in wikipedia, "Color of Noise". (The audio examples are pretty cool). Basically, white noise, which many ...
1
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1answer
41 views

How to compute delta coefficients in mathematica

I want to get delta coefficients calculated. The definition can be found here. However, I don't know what to do with the minus indices. I have tried computing it in a slightly different way, namely: <...
5
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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 ...
3
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1answer
90 views

Approximating decay rate of an amplitude and frequency of an oscillating function

I have an InterpolatingFunction constructed from a discrete set of values obtained by numerical methods. Let's denote it $f(x)$. The function demonstrates an ...
0
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1answer
113 views

Adding white noise to a signal of two variables

When a signal depends on two variables, e.g., f[k1_, k2_] := Exp[I 0.75 (k1 + 0.3 k2)] + 1.5 Exp[I (0.2 k1 + 0.3 k2)] + Exp[I (0.2 k1 + 0.4 k2)]; where ...
5
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1answer
2k views

Data filtering using Butterworth filter

I want to filter data using Butterworth filter. I am currently using Matlab and I want to know how to do it in Mathematica. I have the following data: ...
2
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3answers
124 views

Signal Processing [closed]

The image above is the list plot of discrete data I'm working on. Please I need help on how to zero out all the high amplitudes signal from the data. That is all the data in areas circled, I want to ...
2
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1answer
145 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 ...
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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 ...
2
votes
2answers
631 views

How to generate a random signal consisting of the specified functions

Let's assume that I have some particular signal on the finite time interval which is described by function $f(t)$. It could be, for instance, a rectangular pulse with amplitude $a$ and period T; Gauss ...
13
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3answers
351 views

Deleting noisy data from a plot (manually) and export the best remaining data

I have the following temperature time-series. As you can see it contains very very noisy points in some periods (Fig.A). I tried to approach the best data(the black one in the center) based on the ...
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2answers
130 views

How to find the rectangle with those text

In this image: I want to find this rectangle with all contents(without those grid's lines) I think the total of the pixels can help a little like: ...
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,...
2
votes
1answer
191 views

Generate noise time series with given data's PSD

I have PSD data as a 1D array, function of frequency(rad/sec). It is like powerspectrum for damped oscillator. Considering 3 modes, PSD is shown here. I want to generate noise time series which ...
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0answers
68 views

Processing and visualizing data to show Doppler shift [closed]

I want to write a program which can read a .wav file and manipulate the data so I can observe the Doppler effect in a plot. My problem is I can't figure out a way to isolate the frequency x time. ...
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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}) $:- ...
30
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3answers
12k views

What's the correct way to shift zero frequency to the center of a Fourier Transform?

I'm trying to apply a Fourier transform of a one dimensional list of a time history of some quantity using the Fourier function. I'm interested in the frequency ...
9
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2answers
234 views

Frequency of ticks in mechanical watches

I'm looking to find the frequency of a relatively large dataset (or a relatively short audio file) of a repeating sound, like so: Here are the original files, for those willing to play. :) eta2412 ...
0
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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 ...
13
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2answers
525 views

Processing images from NASA's Juno Jupiter Orbiter

Question Can you help me improve what I’ve done to create an enhanced-color picture from an image provided by NASA’s JunoCam? [My work is shown in the penultimate image of Jupiter in this post.] I’...
5
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1answer
183 views

Fourier transform of a complicated function

This question is related to "Numerical Fourier transform of a complicated function" from 2012. I have pretty much the same problem: I have a function $f(x)$ which is complicated to evaluate, and want ...
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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 <...
8
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1answer
253 views

Sample rate severely influences quality of ButterworthFilterModel?

I've hesitated for a while about whether this should be posted to dsp.SE or not, but still decide to discuss it here. Today I was playing with ...
8
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3answers
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 ...
2
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1answer
99 views

Butterworthfilter highpass/bandpass

this should be a fairly straightforward question since Mathematica has included functionality to filter data. Nevertheless, I am not being successful to solve the problem. Following the proposed ...
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 ...
4
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2answers
107 views

Filtering data with timestamps

How to apply filter to data that was sampled in certain moments of time? Examples from documentation deal only with uniformly sampled data: ...
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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: ...
2
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3answers
868 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
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1answer
43 views

How to get a single evaluation of RandomReal in a Block

I want to generate (and eventually sample) a sine wave with a random frequency in the range [½, 1] (i.e. capture somewhere between half and one period of the waveform over the domain [0,1]). The two ...
0
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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 ...
20
votes
1answer
4k views

Extracting information from the result of ContinuousWaveletTransform

I'm trying to analysis a signal and identify some time-frequency information of it. For example, around which time the specific frequency arrives. It appears that Mathematica has very powerful wavelet ...
1
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1answer
98 views

remove noise while preserving peak

I have a data (see this link) which has some wiggles at both end. I tried to apply different filters to smooth the data, like this ...
2
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1answer
59 views

Is there a discrepancy between reported and actual SampleRate in AudioGenerator

When AudioGenerator is used to generate an Audio object, there may be a discrepancy between the specified (and reported) SampleRate and the actual time difference between the samples. This was ...
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4answers
5k views

Savitzky-Golay Filter to smooth noisy data

I do have noisy data and want to smooth them by a Savitzky-Golay filter because I want to keep the magnitude of the signal. a) Is there a ready-to-use Filter available for that? b) what are ...
9
votes
2answers
896 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 ...
7
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1answer
350 views

Working example for the built-in SavitzkyGolayMatrix for doing polynominal smoothing

Have been using various packages SavitskyGolay.m for Savitsky-Golay polynomial smoothing but just noticed the built-in matrix kernel. I am looking for an example ...
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2answers
100 views

Problem with using Integrate and Plot functions [closed]

I'm pretty new to Mathematica. I'm trying to implement the following 2 lines: ...
26
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4answers
7k views

Computing and plotting a spectrogram in Mathematica

How can I compute and plot the spectrogram of a signal/time series/data in Mathematica? I have a WAV file, sampled at 44100 samples/second and I want to generate a spectrogram of that data. Something ...
1
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1answer
281 views

Remove large spikes in data set

I need remove large spikes on my dataset that looks like this: I would like automatically replace the spike with data shown in dotted red segment. Is it possible if I choose the spike interval by ...
27
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4answers
951 views

How fast is my fidget spinner spinning? A sound experiment!

I would like to measure how fast my 6-bladed fidget spinner spins. To do so, after giving it a hard spin, I gently touch the spinner with a wooden stirring stick to create a buzzing sound which ...
0
votes
1answer
202 views

Ideal/Brick wall Low/High-pass filters: Fourier approach not working

I am trying to take a signal (as a list) and separate it into the low frequency and high frequency parts around some split frequency f. Given that what little signal processing I ever studied is now ...
27
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4answers
10k views

Implementing discrete and continuous Hilbert transforms

What is an efficient and accurate Mathematica implementation of the Hilbert transform, for both continuous and especially discretely sampled functions? This transform relates phase and amplitude in ...
0
votes
1answer
431 views

FFT of data to obtain resonance frequencies and correct amplitudes

I have often to do with experimental data (with a certain length and given sampling frequency) where I obtain trajetories of moving objects in 2d. Then I am interested to find out what the ...
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 ...
0
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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 ...
6
votes
2answers
174 views

How to segment nuclei from a noisy image

(data can be downloaded from this link.) I am trying to segment and count nuclei in a noisy 3-D image stack and it is proving to be somewhat challenging. The strategy I could come up with requires ...