MATLAB (MATrix LABoratory) is a numerical computing environment and a fourth-generation programming language. Use this tag with care.. see excerpt.

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Optimize online weighted kurtosis algorithm

I am currently working on a Simulink block designed to perform an online computation of the weighted kurtosis typical of a certain signal. This block is part of a larger control algorithm, which will ...
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14 views

LFSR in communication [on hold]

I need to use Linear Feedback Shift Register (LFSR) to generate random frequencies at which I will be shifting my signal. How can I do that? I don't understand when to choose which taps for a specific ...
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30 views

Designing bandpass FIR filter MATLAB

I am trying to design a FIR bandpass filter for a STM32F407 microcontroller with a passband of 1kHz between 59500 Hz and 60500 Hz or something similar (since I don't really know how tight I can ...
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1answer
45 views

MATLAB center frequency shift

I am wondering how to shift the center frequency of the below complex data from 0, to say 20 MHz (10 MHz to 30 MHz- 20 MHz bandwidth). I tried to change the indexing of the bins but I could not get ...
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4 views

Am to measure fatigue in different individuals using EEG based BCI [on hold]

How do I measure the brain activity using BCI i.e where the recorded signals will be viewed How do I interpret signals that constitute fatigue What method is the best for extraction of these signals ...
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2answers
51 views

Undoing a filter operation in MATLAB

Out of curiosity, is it possible to actually reverse a filtering on MATLAB. For example, if I have ...
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2answers
54 views

MATLAB $\tt butter$ function

I suspect I have a very basic misconception so I'm trying to clarify that here: A signal should be filtered before it is sampled, correct? That is, I always sample an analogue signal at some sampling ...
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2answers
51 views

Butterworth filtering behaving unexpectedly -MATLAB

I'm new to signal processing but I'm trying to understand how the Butterworth filter works. To do so, I did the following: I assumed a sampling frequency of 100Hz and wanted to attentuate everything ...
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1answer
44 views

Confusion about adjoint of convolution

I have the following problem with convolution operators. I know that if I have a filter $g$, then the adjoint filter would be given by $h(x,y)=g(-x,-y)$, so that $\langle g * u,v \rangle = \langle u,...
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32 views

How to calculate correlation between frames , PDA algorithm

I am working on an assignment in which I am asked to calculate, per frame, the modified correlation between the signal's frames as following: ...
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46 views

What transformation (or similarity metric) is rotation, shift, and scale invariant?

I have an algorithm to to detect copy-move forgeries in images. I used block matching to detect regions of an image that were forged with copy-move forgery and highlighted the alleged areas. For block ...
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1answer
95 views

Problem in understanding DDFS (Direct Digital Frequency Synthesizer.)

I need to generate sine and cosine signals using DDFS (Direct Digital Frequency Synthesizer.) I'm unable to get the idea of the phase increment applied as input which changes the frequency of the ...
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62 views

Save ROI and background in two images

I'm using MATLAB Training Image Labeler app for labeling images and exporting the regions of interest (ROIs) which I save in .jpeg files.The ROIs are exported as a structure $1\times 430$ with two ...
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1answer
37 views

PSD looks to clean/continuous

I generated an signal with a base frequency of $50\textrm{ Hz}$ and its harmonics and quantization noise in it (as an array in MATLAB). It's sampled fast enough to make sure there is no aliasing etc. ...
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1answer
22 views

Smoothed image produces contour-like ripples, yet it disappears in saved image?

I smoothed a grayscale image using a size 10 gaussian filter and display it in Octave (imshow) which resulted in ripples which appears to be contours for image intensity. Yet if I save the image (...
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1answer
86 views

Weighting function for output error IIR filter design

I noticed, when I try to fit filter coefficients to a given complex transfer function with the output error method, implemented for example in the MATLAB function ...
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25 views

How to extract 2D image points from an RGB image?

My approach is to implement Depth Image Based Rendering algorithm. The first part of the algorithm is, m1 = A1*P*M and ...
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2answers
85 views
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2answers
77 views

Frequency shifting of a quadrature mixed signal

I've a quadrature mixed signal with 10 MHz as highest frequency available. I want to shift it to any frequency lesser than 10 MHz. I should get it by multiplying this signal by cosine of the required ...
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1answer
65 views

How is quadrature mixing done?

I've a Gaussian modulated signal whose quadrature and in phase components are separated. I'm multiplying these components with quadrature and in phase components of a signal of 10MHz frequency, ...
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58 views

Frequency shift in signal in MATLAB

I'm trying to shift the signal in the attached image to $0.5\textrm{ MHz}$ frequency. Multiplying it with a cosine of $0.5\textrm{ MHz}$ results in this: I have lowpass filtered the signal to ...
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10 views

Windowing the sequence to compute Correlation

I want to compute the Correlation Functions of the input and output time-domain sequence, ...
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2answers
71 views

PSD of sine wave

I'm learning some basic signal processing to use in my research. So I'm trying to understand the pwelch function in MATLAB to calculate the PSD. My understanding ...
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1answer
35 views

Extracting filter coefficients from frequency response

The frequency response of filter transfer function is given as $$H(j\omega)= \begin{cases} 0 &, \textrm{if }\quad (1+r)\frac{\pi}{2} < \lvert \omega \rvert < \pi \\ 1 + \cos \left ( \...
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46 views

Epilepsy seizure detection in EEG

I want to develop a method to detect the occurrence of epilepsy seizure in an EEG signal. I am using a large data set for number of patients so the algorithm has to detect the seizure in any of the ...
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1answer
53 views

Calculate sum of absolute difference per pixel

I am trying to implement a research paper just to verify my results. I have shared the code (written by me) and the description of the process given in the research paper. Unfortunately my results are ...
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1answer
22 views

How to filter a signal knowing the frequency response of a system in MATLAB?

I have a signal of period $T_0=8$, let's say $x(t)$, and it has the following Fourier coefficients: $$ a_k=\frac{1}{4} \mathrm{sinc}^2\left(\frac{3k}{8}\right) e^{ik\frac{\pi}{2}} $$ for $1\le|k|\le6 ...
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2answers
23 views

How to discover an image clone

I have an image depicting a results of gel electrophoresis (it does not really matter - it just means: no bodies, faces, predictible objects) and I have a strong suspicion that a part of the image ...
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27 views

Wavelets: how to determine scales from frequencies?

(Reposted from StackOverflow) In the following code sample, I would expect the rows of the printed output to match each other, at least approximately. ...
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29 views

removing noise from data

by using ADv(Acoustic Doppler velocimetry) in 200 Hz and 120 s in different depth of river, there is 24000 velocity data in each depth . I want to remove noise from those data. the result must be one ...
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52 views

How to calculate Power spectral density of windowed signal

To compute the (absolute) spectral powers in the above eight frequency bands, PSD of the input signal needs to be estimated. The PSD of a signal describes the distribution of the signal’s total ...
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1answer
32 views

Matlab: Separate data samples from signal

I have data samples for an EMG signal of three arm reps. In the data I have 1 signal that is flat then fluctuates in voltage then becomes flat again shows three pulses for each rep. I want to separate ...
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1answer
32 views

Classifying Discrete time filter

So let's say i have this frequency response of a digital filter: My question is how can i classify this type of filter ( low pass, high pass,...)?
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1answer
33 views

Soft question: Seeking compressive sensing imaging demo in MATLAB

I am looking to experiment in MATLAB with image restoration/reconstruction using compressed sensing. I am relatively new to compressive sensing, and was inspired by the following Wired article to ...
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1answer
46 views

Difference between $\tt rand()$ and $\tt randn()$ in MATLAB [closed]

rand() is for "Uniformly distributed pseudorandom numbers" I generate two rand arrays, and then use the cross-correlation (<...
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11 views

How to hide the number on the constellation points in matlab? [migrated]

This is how you plot a constellation: hMod = comm.RectangularQAMModulator('ModulationOrder',32, ... 'SymbolMapping','binary'); constellation(hMod) but how do ...
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1answer
47 views

How to find PSD (Power spectral density) of spatial data

I have profiled a surface, measuring the height of peaks and troughs at 0.02mm intervals. I have 1501 data points, the below listed as an example: $$\begin{align} x &= 0\,\mu\text m & y &...
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17 views

How can I estimate a signal similar to my data using ar modeling in matlab

To be more specific, I have a time series which corresponds to a section from an EEG signal. The idea is obtain AR coefficients and then use these coefficients to create a simulation where I can get a ...
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11 views

Time shift in DWT using Mallat algorithm over the $2^{10}$ scale

I am doing DWT on $2^{10}$ scale using the Mallat algorithm. As I know, DWT using the Mallat algorithm decimate sampling frequency 2 times at every next scale, it means $F_s$ is different for each ...
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1answer
15 views

Do I need an I-Q (in-phase/quadrature) mapper in Simulink with the QAM modulator?

Would it be correct if I use the Random Integer Generator block with a certain $M$-ary number (say $M=16$) followed directly by the ...
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1answer
32 views

How to calculate Long Term Average Spectrum of an audio file?

I'm working with audio files and I have to find their long term average spectrum. Although I had an option available in the software Praat but I don't understand the algorithm of finding the spectrum. ...
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20 views

object selection from an image using watershed

I have already done the thresholding and skeletonising that image for the separation of the fiber.How to separate a fiber from a group of fibers and to find out the length and other properties of that ...
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59 views

RLS or another way to solve Ax=b in batches

I need to solve a system of linear equations to do the imaging. My A is 60k by 10k or so and not full-rank. What are the ways to proceed? I tried matlab built-in LSQR algorithm, which allows ...
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48 views

GCC-PHAT Python

I'm implementing a GCC-PHAT function from matlab to python using this code (as the gccphat function in matlab) : ...
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1answer
25 views

Power/Amplitude Response of a system

I am currently looking over filters and understand the frequency response of a system, e.g. a low-pass filter. However I am confused by the 'Power/Amplitude response' of a system as detailed in my ...
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1answer
39 views

Wavelet transform in MATLAB

Suppose I have a wave with $20 \textrm{ kHz}$, $100 \textrm{ kHz}$ and $300 \textrm{ kHz}$. Sampling frequency used is $1000 \textrm{ kHz}$. I apply the discrete wavelet transform on the wave like <...
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42 views

Implementing blind deconvolution in MATLAB

I want to implement blind deconvolution for the signal $ r(n) = h(n) \star s(n) + a(n)$ in MATLAB where $r(n)$ is the recorded speech $h(n)$ is impulse response of room acoustics $s(n)$ is desired ...
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26 views

How do we find the Power Spectrum Density (PSD) and which data type is valid for that?

I want a simple explanation on how to find PSD and which type of data (in which units, I mean) can be used for doing so. If found similar interesting questions 1 & 2 and some on Mathworks, like ...
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2answers
25 views

How does MATLAB's $\tt upfirdn$ select extra points when downsampling?

I had a signal 512 samples long and I used upfirdn to filter and downsample it by a factor of 2. I thought this would result in a 256 sample long variable, but ...
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18 views

Generating discrete filter polynomials in Simulink

I would like to implement some digital filters in Simulink. I tought of using the Discrete Filter block. To do so, I would like to generate the discrete polynomials of the filter with a tool instead ...