Questions tagged [signal-processing]
Digital signal processing of sound, video or other single or multidimensional data
251 questions
2
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0
answers
136
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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 ...
- 347
2
votes
0
answers
247
views
Analysis of the periodic data by the maximum entropy method
I am trying to get the frequency spectrum of periodic data. Since the data set is short, the outcome of the frequency peaks are not sharp enough for me to do further analysis. I know the spectrum can ...
- 21
2
votes
0
answers
171
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 $9\times 2$ ...
- 361
2
votes
0
answers
395
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 ...
- 33
2
votes
0
answers
435
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 ...
- 21
2
votes
1
answer
2k
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Plot periodic function from Dirac delta function [duplicate]
Sorry for my bad english.
I need to plot periodic function from dirac delta:
δT(t)=∑δ(t–n*T), where T - is a constant, and n=-20..20
And after them, plot new function fd=f(t)*δT(t) - discrete signal ...
- 21
2
votes
0
answers
920
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Doing local FFT on huge 3D vector data cell mesh and visualizing it spatially?
Simulation type:
I'm running a simulation with the OOMMF micromagnetics package
http://math.nist.gov/oommf/
where are magnet is represented by a mesh of 3 million cells, it gets excited by a ...
- 247
1
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3
answers
347
views
1
vote
2
answers
723
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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 ...
- 119
1
vote
1
answer
168
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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:
...
- 887
1
vote
1
answer
173
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Noise filtering in audio
I was given audio with white Gaussian noise and i have to implement two types of filter: Rectangle and Triangle that filter out redundant frequencies and reduce the amount of noise
Here is the code ...
- 41
1
vote
1
answer
1k
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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 ...
- 3,511
1
vote
1
answer
718
views
Gauss Markov Process
I am trying to model a 1st order Gauss Markov Process (gyroscope drift). I know the Allan Variance characteristics of the process (bias instability, random walk characteristics).
I know the model ...
- 1,867
1
vote
1
answer
162
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Microfluctuations analysis and Power spectrum
I measured a parameter over time and obtained the values below:
0,627896 0,205004 0,259237 1,059125 0,832184 0,587992 0,565537 0,527323 0,460228 0,471958 0,26696 0,75367 ...
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1
vote
1
answer
489
views
DSP filter problem in the simulation of a Lock-In amplifier
I wanted To explain to students how a Lock-In amplifier works. The best way is to simulate the behaviour of one. However, in my program, I get unexpected behaviour, which I suspect has to do with ...
- 81
1
vote
1
answer
186
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Remove regular transient spikes from - otherwise - pretty level data
and let me just say thank you for all the help you good people have been providing to stalkers like me through the years.
So, in the next few days or months or years, I'll be acquiring data of the ...
- 343
1
vote
2
answers
284
views
Two-tone spectrogram
The default spectrogram command uses a single color and appears to just vary the saturation of the color to express intensity. So, for example, in the default implementation which looks like this:
...
- 4,102
1
vote
1
answer
3k
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Detecting beat frequency using FFT
I wrote Mathematica FFT code that works for non-beat signals, eg. Sin[2*Pi/20*x] and more complicated but I can't obtain beat frequency of Sin[2*Pi*(10)*x] + Sin[2*Pi*(11)*x]. Also, what is general ...
1
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1
answer
1k
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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 ...
- 3,167
1
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1
answer
253
views
Implementation of a Hanning filter
I'm implementing a package for in-house signal processing.
I wrote here a quite trivial function implementing a Hanning windowing of the signal.
...
- 696
1
vote
1
answer
172
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IIR Digital Filter: samples not matching the frequency response
So I am a small project in Mathematica involving a Chebyshev 4th order highpass filter, and to obtain its digital IIR filter with the bilinear transformation.
Then I implement the differences equation ...
1
vote
1
answer
135
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Track the location of of dot from noisy image
https://i.sstatic.net/QDXKL.jpg (subtraction between the image)
https://i.sstatic.net/9zqWV.jpg (orignal image)
From the original image, since my CCD camera is bad, I cannot really see anything.
...
- 1,830
1
vote
1
answer
57
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:
<...
- 21
1
vote
1
answer
445
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
...
- 17.4k
1
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2
answers
204
views
How to detect the singular value with wavelet analysis
I have a series data
data=Uncompress[
FromCharacterCode[Flatten[ImageData[Import["https://i.sstatic.net/ApipY.png"],
"Byte"]]]];
We can show it
...
- 27.2k
1
vote
1
answer
179
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:
...
- 463
1
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3
answers
133
views
1
vote
1
answer
77
views
Why do I get this error message from LowpassFilter?
I have a list of numbers data of length 10^7.
I have values
rate = 100000.;
cutoff = 2000.;
I try to low pass filter with
...
- 1,941
1
vote
1
answer
140
views
Fourier Spectral Analysis [closed]
I'm currently working on an engineering exercise that goes as such:
I know that I need a step function to model the square waves, but I'm having trouble finding the right functions to generate the ...
- 105
1
vote
1
answer
231
views
Finding the phase difference between fundamental harmonics of two waveforms [closed]
I have two periodic non-sinusoidal waveforms $WV1$ and $WV2$ (See Figure). I want to extract the fundamental components of these two (i.e. $WV1_{F0}$ and $WV2_{F0}$) and find the peak amplitudes and ...
- 169
1
vote
1
answer
68
views
Creating time varying 2d coordinates with OrnsteinUhlenbeckProcess
I see that I can create time varying 1d data with e.g.
...
- 2,396
1
vote
1
answer
116
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 ...
- 475
1
vote
0
answers
173
views
How to Model a Parametric Fast Fourier Transform in Mathematica?
I'm using this code which evaluates the FFT of my original signal (which is a time series). Using the Manipulate function of Mathematica it is possible to vary the ...
1
vote
1
answer
196
views
Calculation of CIC/FIR filter is too slow
I'm investigating the propeties of Cascoded Integrator Comb (CIC) filter. (for sigma-delta modulator application). I have 2 quesitons and below is what I have done:
a). Any alternative method to ...
- 147
1
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0
answers
57
views
Phase unwrapping of transfer function model for calculating group delay [duplicate]
Suppose that I have a transfer function model
...
- 61
1
vote
1
answer
329
views
How to excite a transfer function with continuous white noise
I'm trying to get the output response of linear system represented by transfer function, once the white noise is given as an input. Here's the code:-
For generating continuous noise, I'm getting help ...
- 13
1
vote
0
answers
216
views
How to compute Total Harmonic Distortion (THD) for the following signal?
The signal is as follows
Sin[x - j]
with $j$ being
...
- 55
1
vote
0
answers
121
views
How to convolve two audio signal?
Can we obtain reverb effect by convolve two audio signal?
Here are some example.
https://www.bilibili.com/video/BV1vE411h7W2
- 11
1
vote
0
answers
76
views
SpectrogramArray timescale
I have a 600 second @ 8000 Hz WAV file which need to be analyzed in detail in terms of events (red parts in plot) defined in time and frequency that need to be rather exact, in particular the ...
- 115
1
vote
0
answers
70
views
Is there some programs about the fast inverse descrete time Fourier transform
At first, I give the definition of the inverse discrete-time Fourier transform
$$\phi(s)=\frac{1}{2\pi}\int_{-\pi}^{\pi}\exp(iks)f(k)dk$$
Here what I use is
...
- 173
1
vote
0
answers
34
views
What's the parameters of the Spectrogram function
The Spectrogram functions only has these parameters listed:
Spectrogram[list,n,d,wfun]
What's the value of the other ...
- 61
1
vote
0
answers
94
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 ...
- 31
1
vote
0
answers
89
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 ...
1
vote
1
answer
125
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 ...
- 97
1
vote
0
answers
63
views
How is the PowerSpectralDensity function implemented? [closed]
I am working on a signal processing lecture for undergraduate students with Mathematica exercises/examples, and I would like to explain to them what happens when they run the ...
- 363
1
vote
0
answers
88
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 ...
- 11
1
vote
0
answers
111
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.
...
- 203
1
vote
0
answers
52
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}) $:-
...
- 3,509
1
vote
0
answers
41
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:
...
- 11
1
vote
0
answers
165
views
wavelet fourier transform
I want to do wavelet Fourier transform of my data but I have few doubts in this. 1)first of all what is octive and voice command here when i am changing value according to that my plot is changing but ...
- 11