Digital signal processing of sound, video or other single or multidimensional data
3
votes
1answer
77 views
How does Mathematica's LowpassFilter work?
I don't really understand the documentation for the LowpassFilter[] function in Mathematica. In the course I have about signal processing, low-pass filters come in ...
1
vote
0answers
237 views
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 ...
0
votes
0answers
130 views
Obtaining fourier transform for Root Raised Cosine pulse
I have been trying to obtain the Fourier transform for time domain root-raised-cosine pulse using Mathematica. The answer I'm getting from Mathematica is not the correct answer. When I input the ...
21
votes
7answers
610 views
Graphical representation of a moving sound source
Some explanation since I have got a specific and another more open-ended question:
I used two microphones in a 90° arrangement (see picture below) to capture sound from a source moving around the room ...
1
vote
1answer
287 views
BodePlot Phase disagrees with convention. How do I make it agree? [closed]
This question is similar to a previous question, but I did not find an adequate answer there.
If I type in the command BodePlot[1/(s^2)] I get a horizontal line ...
10
votes
3answers
445 views
What is Mathematica's equivalent to MATLAB's filter function?
The MATLAB code
filter(0.5,[1, -0.5], [1:10])
is equivalent to
Rest@FoldList[(#1 + #2)/2. &, 0, Range[10]]
I don't ...
0
votes
1answer
144 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 ...
4
votes
1answer
192 views
How to get the total intensity of a certain frequency range in an audio file?
Does anyone know how to get the total intensity of a certain frequency range in an audio file?
Let's say an audio file has a frequency range from 0Hz to 20KHz, and I want to extract the total ...
2
votes
1answer
214 views
Spectrogram of complex exponential functions in Mathematica 9
How can the v9.0 built-in Spectrogram[list, n, d] function be modified to accept complex exponential functions?
The V8.0.4 code that produces the result I'm ...
2
votes
1answer
205 views
Obsolete Signal Processing functions
I need some tools to detect the fundamental frequency and pitch of a sound. I Googled for "pitch detect" and found some .nb files that do these tasks, but all the files are in Mathematica 3.0 format. ...
-3
votes
1answer
162 views
Given a time series of n samples with a known probability mass function, how can I predict the next sample? [closed]
What I would like to do is create a tool that takes as an input, a set of samples that are known to behave according to a known probability distribution and predict the next sample. The tool will ...
3
votes
0answers
647 views
Eulerian Video Magnification with CurrentImage[] [closed]
I saw yesterday a post here in SE that I think was deleted. It was about the recently published MIT algorithm called "Eulerian Video Magnification for Revealing Subtle Changes in the World ACM ...
27
votes
4answers
579 views
Filtering beat-to-beat heart rate data
From an experiment, I have a dataset of beat-to-beat heart rate data: a list of the time between each heart beat in [ms].
The data is measured using an infrared optic sensor at the finger tip. The ...
6
votes
0answers
182 views
Cluster a signal into areas of equal intensity
Introduction
I have a greyscale photograph that I want to partition into areas of equal intensity.
This means, that the integral over each partition should be (roughly) equal.
There is no unique ...
16
votes
5answers
2k views
How to find the phase difference of two sampled sine waves?
I'm trying to measure a phase difference between two Sine functions I've acquired with a computer. I'm uploading one of the .txt files with the data I'm working with here: txt file. To remove the ...
15
votes
1answer
1k views
How to demodulate an FM signal in continuous-time?
I'm not sure if this is a math or Mathematica question, but I'm posting it here because I'm interested in possible Mathematica tools/functions to solve the problem.
I'm stuck. I want to simulate ...
2
votes
1answer
278 views
non-linear trend reduction using thresholds
Doing some mappings of the earth magnetic field results in the left-hand figure below (which consists of 181 profiles):
To improve this I tried a non-linear trend reduction using, for example,
...
17
votes
2answers
391 views
Implementing continuous phase/Arg function
In MATLAB there's a function called phase that is just like our Listable friend Arg, but ...
6
votes
3answers
455 views
How to properly plot a response of a transfer function in Mathematica?
I'm trying to display the output response of a transfer function in Mathematica with and without a compensator. The problem is very strange: while the transfer function compensate is showing well, the ...
17
votes
3answers
1k views
Can one find the beat of a tune with Fourier analysis?
I'm trying to find out if it's possible to find the beat of a tune by Fourier analysis with Mathematica. I'm taking a 44.1 kHz sample sound and hoping that I might get a nice peak for a frequency ...
18
votes
3answers
2k 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 ...
12
votes
4answers
1k views
Numerical Fourier transform of a complicated function
Say I have a function $f(x)$ that is given explicitly in its functional form, and I want to find its Fourier transform[1]. If $f$ is too complicated to have an analytic expression for $\hat f(k)$, how ...
12
votes
3answers
2k 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 ...
