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Questions tagged [signal-processing]

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

2
votes
2answers
121 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: ...
11
votes
3answers
250 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 ...
1
vote
1answer
72 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 ...
3
votes
0answers
146 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
108 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 ...
1
vote
0answers
58 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. ...
1
vote
0answers
37 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}) $:- ...
0
votes
0answers
47 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
votes
2answers
452 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’...
9
votes
2answers
182 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 ...
5
votes
1answer
144 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 ...
2
votes
0answers
36 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
votes
1answer
238 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 ...
2
votes
1answer
91 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
votes
0answers
49 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 ...
2
votes
2answers
168 views
4
votes
2answers
85 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: ...
1
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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: ...
0
votes
1answer
34 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
votes
0answers
60 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 ...
1
vote
1answer
76 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 ...
0
votes
2answers
77 views

Problem with using Integrate and Plot functions [closed]

I'm pretty new to Mathematica. I'm trying to implement the following 2 lines: ...
1
vote
1answer
113 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
votes
4answers
889 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
152 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 ...
0
votes
1answer
283 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 ...
2
votes
1answer
54 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 ...
0
votes
0answers
45 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 ...
0
votes
0answers
48 views

Prevent running out of memory when doing SpectrogramArray?

I was using SpectrogramArray[Import@"myFile", 22050, 22050]to transfrom a piano mp3 file so that I can (probably?) generate a midi file from that mp3. The step size ...
6
votes
2answers
166 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 ...
1
vote
2answers
98 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: ...
1
vote
1answer
512 views

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 ...
2
votes
2answers
168 views

Plot cumulative distribution of a function

I want to calculate the probability $P(X\le-0.5)$. I have the probability density function $1/(\pi\sqrt{A^2 - x^2})$. $A$ is supposed to be the square root of noise power, $A = \sqrt{N_0}$, and so ...
3
votes
0answers
91 views

FIR filter and the relation between Sample rate and cut-off frequency

I have problem to unterstand the logic of the cut-off frequency of the FIR filter. Suppose my sample rate is 2MHz and I want to design a lowpass filter with a cut-off frequency 100Hz. What will be $\...
1
vote
0answers
91 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 ...
2
votes
1answer
463 views

Cut off frequency of low pass filter

I have a data here, I want to make sense of Lowpass filtering function in Mathematica.I do not fully understand units of cut off frequency in this option since the data is in frequency space. What I ...
2
votes
0answers
145 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 ...
0
votes
0answers
61 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 ...
8
votes
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
votes
0answers
87 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 $9\times 2$ ...
0
votes
0answers
68 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 ...
0
votes
1answer
106 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 ...
6
votes
1answer
459 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?
3
votes
1answer
96 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 ...
1
vote
1answer
60 views

Creating time varying 2d coordinates with OrnsteinUhlenbeckProcess

I see that I can create time varying 1d data with e.g. ...
2
votes
1answer
155 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 ...
1
vote
2answers
114 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 ...
5
votes
2answers
179 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 ...
2
votes
1answer
299 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(...
0
votes
2answers
104 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: ...