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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Remove unwanted object of image in Matlab?

I am trying to remove the unwanted object. I have an image that includes a house and the trees. I am trying to remove the trees. I am using 'imsubtract' to remove small edge. But the result is not ...
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0answers
15 views

Sliding windows and crosscorrelation of periodic signal

I am doing cross correlation in MATLAB, and have it working for generalized cross correlation (GCC), and also for GCC-PHAT (GCC with a phase transform weighting function). However, when using a ...
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0answers
8 views

how to open image according to the selected image [closed]

i am using the gui and code for selecting an image is as follows: ...
-2
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0answers
27 views

Extracting features from songs for a beginner [closed]

I' am working on an machine learning project in MATLAB which requires me to extract features from songs. I'm a complete beginner to signal processing and frankly I'm a little overwhelmed. I' am fine ...
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1answer
25 views

Errors when converting from digital filter object to transfer function

I am trying to use the designfilt tools in MATLAB to create a bandpass filter, but to be compatible with other code I need the resultant filter in transfer function ...
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0answers
34 views

Audio - TDOA and $\tt xcorr$, find the 'best' peak

I try to locate a mobile device using multilateration. The mobile device acts as the receiver and in the room I have three speakers. To calculate the position I need the time difference of arrival (...
-2
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0answers
27 views

MIT ECG data base

I had downloaded a ECG data set ($100\rm m$) from MIT arrhythmia data base. The data points shows values ranging from $900$ to $1100$. I know that maximum $R$ wave amplitude in ECG wave form is $0.6\...
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0answers
25 views

MATLAB - Stereo signal wav file generation with time and gain changes per channel

I need to create short bursts of sound, ideally clicks, where one channel is out of sync with the other (left and right) either in terms of time or gain. This I need to output as a wav file. How do I ...
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3answers
61 views

How to design a digital filter with a frequency dependent phase delay?

I want to design a filter with a custom phase delay related to frequency. As frequency increases, phase delay should increase. The time delay as a function of frequency can be expressed as: $t_d = \...
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0answers
35 views

Polyphase Analysis Channelizer in MATLAB

I am attempting to reproduce results for both polyphase analysis and synthesis channelizers found in "Non-Maximally Decimated Filter Bank and Its Applications in Wideband Signal Processing". Detailed ...
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1answer
35 views

Frequency analysis of a signal with not constant sampling frequency

I'm a stack exchange user for some time and now I'm registering to ask a simple question (I think!). I have a vibration signal with an amplitude and time (sampling frequency not constant) in a $...
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0answers
20 views

FIltering data from Accelerometer in soil (Shaking table test)

I performed a test in a shaking table in San Diego. In this test, there were several accelerometers embedded at different depths in the soil. I am using these accelerometers to determine the ...
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1answer
23 views

BiLinear Downsample and Upsample Equivalent Filter or Operation

Let's say I have an image mInputImage with numRows and numCols. I resize it using Bilinear ...
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0answers
21 views

Speaker Identification Neural Network Training

I am implementing a speaker identification problem by extracting features using MFCC coefficients. Say for one speaker I have a training data with 50 different lines read and each line now at ...
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1answer
32 views

Cross-correlation and auto-correlation of an image using $\tt fft$

I'm working on a project where I have to find the auto-correlation and cross- correlation of types of pixels in an image: I am using MATLAB and my code for the autocorrelation is: ...
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0answers
39 views

Detecting special points in signal

What tool/filter/mathematic operation would you use to detect the red points marked in this signal? As you can see there are several differentiated groups and I want to detect those moments in ...
5
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3answers
80 views

MATLAB: $\tt fft$ and $\tt ifft$ scaling

In MATLAB, the outputs of the fft and/or ifft functions often require additional processing before being considered for analysis....
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1answer
33 views

GCC-PHAT (Generalized cross correlation MATLAB)

I've been trying to implement generalized cross correlation with a PHAT weighting function for a while now, and cannot get it to work. I have tried correlating using MATLAB's xcorr.m file, and it ...
1
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1answer
34 views

Nyquist with only poles at the origin

I need to solve this three exercises: $$G_1(s) = \frac{1}{s}$$ $$G_2(s) = \frac{1}{s^2}$$ $$G_3(s) = \frac{1}{s^3}$$ This is what I did: For the single pole ($1/s$), magnitude of A is $\infty$ ...
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1answer
31 views

correcting wobbling motion in sinogram

I have measured some sinograms of a specific sample. However, there is some wobbling motion that disturbes the resulting images. Since the red upper and lower lines (indicated with black arrows) are ...
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1answer
30 views

Wavelet transform 3D plot for CoP

I'm trying to perform wavelet transform and make a 3D plot like : With the wavelet transform function : $$ \textrm{CWT}_x^\psi (\tau, s)=\frac{1}{\sqrt{\lvert s\rvert}}\int x(t)\psi\left(\frac{t-\...
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0answers
34 views

Phase correlation vs. normalized cross-correlation

I asked this over at Mathematics Stack Exchange, but since this sort of lies on the border of the questions normally asked over there and the questions you see over here I'll ask it here as well. (As ...
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0answers
29 views

generate signal with multiple frequency

I'm trying to create a multichannel multi-frequency signal. I've seen some code to generate a signal with only one frequency , but I need to have a signal with two or more frequencies simultaneously. ...
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0answers
12 views

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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42 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
51 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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2answers
54 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
60 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
52 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
46 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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0answers
34 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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0answers
49 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
117 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 ...
2
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0answers
66 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
39 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
24 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
92 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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0answers
28 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
88 views
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2answers
80 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
74 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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0answers
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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0answers
13 views

Windowing the sequence to compute Correlation

I want to compute the Correlation Functions of the input and output time-domain sequence, ...
0
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2answers
84 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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0answers
56 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 ...
0
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1answer
62 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
24 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
24 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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0answers
31 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 ...