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Questions tagged [signal-processing]

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

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28 views

How to add vertical lines under points? [closed]

Say I have a list x, and I want to draw a plot, so I will use the below code: x = RandomReal[1, 10] ListPlot[x] However, I ...
120 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 ...
26 views

Find repeating chunks in audio file

I have a long audio file (12+ hours). I know that there are some unknown small (2 minutes each or thereabout, it varies) repeating (not bit by bit: it is recorded with a mic) chunks in it, repeating ...
18 views

Plotting DiracDelta series

I'm dealing with the Fourier Transform of the following signal: ...
22 views

Why is the number of sample points of an audio changed after being export?

I have an audio audio001 and I need to export/import it so that I can do auto-correlation. Below I used ...
6k views

Implementing continuous phase/Arg function

In MATLAB there's a function called phase that is just like our Listable friend Arg, but ...
151 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 ...
30 views

Plot Audio DAta

I am a beginner in mathematica. Currently i am working on audio file my problem is when i extract audio information using BinaryReadList and try to plot it works with mono wav file but cannot get ...
35 views

How to filter audio to get best results in correlation?

I am trying to recognise the alphabetical letters by saving some data of records of me and others saying each letter, then comparing a test audio not contained in the data to each letter using the ...
50 views

Removing Extra Points When Finding an Audio Envelope

I am trying to reproduce Camtasia's way of displaying audio signals which is a strictly positive envelope of the audio signal and very easy for me to identify some sounds visually. These are displays ...
49 views

Fourier Transform and Inverse Fourier Transform of Lists

I am trying to compute the Fourier transform of a list, say an array of the form {{t1, y[t1]},.....{tn, y[tn]}}; apply some filters in the spectral components, and then back transform in time domain. ...
291 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 ...
43 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: <...
61 views

GaussianMatrix algorithm details

GaussianMatrix[] supports a Method -> "Bessel" option which the documentation describes (in the Details section) as: With ...
103 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 ...
168 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 ...
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: ...
129 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 ...
151 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 ...
68 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 ...
659 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 ...
420 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 ...
138 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: ...
194 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,...
271 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 ...
69 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. ...
41 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 $(-\frac{1}{2},\frac{1}{2})$:- ...
13k 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 ...
269 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 ...
54 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 ...
574 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’...
215 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 ...
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 <...
262 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 ...
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 ...
106 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 ...
70 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 ...
176 views

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117 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: ...
30 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: ...
934 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"]] ...
53 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 ...
103 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 ...
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 ...
115 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 ...
62 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 ...
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 ...
920 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 ...