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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32 views

Simple fft to Gaussian pulse with MATLAB

trying simply to create femtosecond pulse in MATLAB exactly like in the attached image, the carrier frequency is around 374THz, and my sampling frequency is 10 times the carrier. The results of ...
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55 views

Why does a phase shift in the frequency domain not produce a time delay in the time domain?

Suppose I have an input signal which represents a vehicle front suspension response that has been measured using an accelerometer. It is seen that the measured rear suspension response is effectively ...
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12 views

Issue in partial correlation

For a time series I wanted to plot separately the partial auto correlation. Below is the graph for MA model that I want: This shows plot of two time series of two time series - one is a sequence ...
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0answers
28 views

Instantaneous power estimation by discrete hilbert transform - how far does it smooth?

In my research area, instantaneous power in a specific frequency band is commonly estimated by the following procedure: Apply a bandpass filter on the raw signal (e.g. 80-90Hz bandpass). Estimate ...
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1answer
27 views

How to change the start point of resampling process?

I'm trying to resample a digital communication signal in SciPy or Matlab. Suppose the signal was sampled at 3 samples per second, and I want to resample it to 2 samples per second, the thing is I also ...
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25 views

How can I simulate a broadband ultrasound transducer in Matlab?

I am using a Matlab model to send a broadband acoustic pulse across a fluid. The centre frequency should be 50kHz with 100% bandwidth. It has been suggested that I apply a window the pulse to ...
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1answer
44 views

map two RGB images in Matlab

I wonder is there any algorithm or method that I can map two RGB images together in Matlab. I mean assume I have following images Is there any way I find what number I should multiply each ...
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1answer
45 views

Fixed SNR with unitary noise variance

I've just one question : How can I write a model like y = x + w,( with w a white gaussian noise) with a fixed SNR and a noise variance equal to 1. What coefficient may I have before x ? Thanks !
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2answers
103 views

Plotting Real Amplitude of Sine Wave in FFT

Consider a sine wave having an amplitude of 9 and a frequency of 0.3 Hz. I wish to perform an fft and plot the frequency on the x-axis and the real amplitude (i.e. 9) on the y-axis. I am using the ...
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0answers
37 views

Issue in crest factor

From Wikipedia: Crest factor is a measure of a waveform, such as alternating current or sound, showing the ratio of peak values to the average value. It is the ratio of peak amplitude of the ...
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0answers
16 views

Calculation of Heart Rate from Pulse Plethismography [closed]

Can anyone tell me how can I calculate heart rate from the ADC data from a pulse plethismograph in Matlab?
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1answer
43 views

Matlab FFT keeps plotting mirrored values

My Matlab FFT plot keeps showing the mirrored values of my frequency of interest. In this example I am looking for 250Hz with a 3200Hz sampling freq. The FFT plots my value at 266Hz as well as 1330 ...
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45 views

Why is level of power spectrum dependent on FFT resolution?

I created a sinusoidal wave in some noise, and plotted the power spectrum of the signal using two periodogram estimates (welch procedure). One estimate is 'high resolution' - i.e. it uses a longer ...
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1answer
56 views

How to reconstruct the signal which is subjected to FIR filtering - Matlab

I have a signal $x$ which is corrupted by Gaussian noise. The signal $x$ is convolved with a filter with coefficients $h = [1, -2, 1]$, to generate signal $y$. Now the signal is taken to Discrete ...
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2answers
36 views

2D-otsu algorithm in Digital image processing

I'm working on image project using Matlab & I heard about 2D-otsu algorithm as effective segmentation with low SNR and low contrast images, but I can't find enough information about it or how to ...
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0answers
17 views

Partial derivative simulation software [closed]

Is there any way I can simulate partial derivative either in matlab or any other simulation software . The drawback in MATLAB ( PDE toolbox) is expensive. Is there any alternative free simulation ...
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0answers
44 views

Ways to find three curves from palm image

I am asked to extract three curves from palm images. original image expected result. The curves has lower intensity than ...
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0answers
42 views

Not obtaining conjugate symmetry

In Matlab, I have set up input cosine signals with different frequencies and also time delayed versions of the signal. The idea is that a time delay would produce a phase shift in the frequency domain ...
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1answer
48 views

Generating a Sine Signal (for example a voltage sine wave) with changing frequency and changing sample rate (time)?

i have a measured signal (e.g. voltage sine wave) and i would like to generate a sine wave which matches this meausred signal (with the generated sine wave i remove the harmonics from my measured ...
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0answers
14 views

sine signal-->gaussian noise-->fading channel for SNR analysis

I'm new to matlab and need some help. I have a project whereby i want to to analyse the SNR of a sine signal which passes through an Additive White Gaussian Noise (simulating weather conditions) and a ...
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1answer
28 views

How to average coherences estimated using Welch's method in MATLAB

I'm trying to estimate the average coherence of discontinuous snippets of a signal in MATLAB. For Welch's spectrum estimates, the following works: ...
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0answers
11 views

Generating a Sine Signal (for example a voltage sine wave) with changing frequency and changing sample rate (time)? [duplicate]

i have a measured signal (e.g. voltage sine wave) and i would like to generate a sine wave which matches this meausred signal (with the generated sine wave i remove the harmonics from my measured ...
0
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1answer
29 views

Basics of waveform, how to define the zero point

Audio is a sequence of waveforms which have peaks, troughs, 0, just like below. How to define the x axis (y = 0) in the picture, how to choose the 0 point in the waveform since there are so many ...
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3answers
459 views

disadvantages of FFT, it can not extract enough frequencies without enough samples

Let's say sampling rate is $Fs = 44\mathtt{kHz}$, now I have $N = 2048$ samples, then I can get $N/2 + 1 = 1025$ frequencies. I'm confused by Matlab's FFT documentation that says the frequencies are ...
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1answer
22 views

Correct way to implement Discrete and Stationary Wavelet Transform?

Can someone please confirm if this is indeed the correct way to compute DWT: ...
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5answers
101 views

How to detect impulse like peaks - Matlab

I have a signal which is a matched filter output. whose values are given here: Amplitude values Input to this matched filter is radar return signals mixed with additive gaussian random noise. ...
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1answer
79 views

Frequency response of a filter - fft vs. freqz

I have designed my filter using firhalfband(N,Fo,A), which gives me the filter coefficients. Then I try to see the frequency response of it. I use these two ...
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0answers
18 views

algorithm Matlab function 'stream2' and 'stream3' use to compute streamline

Can anyone explain how the MATLAB functions: stream2(x,y,z,u,v,startx,starty) and stream3(x,y,z,u,v,startx,starty) compute stream lines from vector data u and v? In the stream2.m file, it calls the ...
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0answers
22 views

Clustering of overlapping windows (K Means)

I'm attempting the clustering of some of my data using a K-means Euclidean square method. I've broken the data down into small windows, 200 samples in size, but with a 50% overlap. I've chosen to use ...
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1answer
66 views

FFT Matlab - Meaning of Frequency Vector

I'm following a tutorial about the FFT. It's well explained but I don't understand the meaning of the frequency vector: ...
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1answer
40 views

Approximate a system frequency response with a filter in Matlab

suppose I know the frequency response of a (linear) model approximating a real physical system but only at a specific frequency $f_0$ (so basically I have a complex number whose module is the ...
0
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1answer
42 views

Make a movie from multiple images in MATLAB [closed]

I have 10 images in the folder say "D:\images\" named as frame1,frame2,...,frame10. I want to make a movie from the color images with frame rate as per choice.Also i want to save created video file in ...
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1answer
13 views

coefficients of farrow structure

what is the method for generating coefficients for farrow structure in matlab. I am designing a low pass filter using firpm but the output of farrow structure is not delayed.
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1answer
61 views

How to simulate AWGN in communication systems for specific bandwidth

I am trying to generate a AWGN waveform to add it to the signal of my simulated communication system. The operating bandwidth of the communication system is about ...
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1answer
33 views

How to normalize frequency in MATLAB

I know all about conversion of frequency from HZ to normalized frequency and from normalized frequency to angular frequency ,but I wonder how it is done in MATLAB. I have the following code: ...
0
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1answer
27 views

Demodulation with matlab

I am trying to listen VLF radio signals. I have a recorded wave file (download) and here is the frequency spectrum: I have produced this spectrum using this matlab code: ...
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2answers
62 views

How to visualize and understand Gabor filter using matlab

I am reading a paper, in which the author defines gabor kernels as : $$ \psi_{\mu,\nu}(x,y)=\frac{\lVert \mathbf{k}_{\mu,\nu} \rVert}{\sigma^{2}}\exp (-\frac{\lVert ...
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0answers
26 views

Time delay analysis in different binary sequences

I am extracting a property of a signal which I represent with either a 0 for absent or 1 for present. This property is extracted for each data point in a time series and in the end I am left with a ...
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0answers
31 views

Find Chessboard Corners using RANSAC in Matlab

I have a question: I want to implement an algorithm to find chessboardcorners out of set of given points. I have an image where I already have all the chessboardcorners there are, but also some ...
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2answers
99 views

Created Matlab echo signal: Is it an actual “echo?” Or am I just manipulating the signal to make it seem like an echo?

This is just an outline of what I did (assume that all my dimensions fit): ...
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1answer
30 views

how to visualize image segmentation using matlab

After clustering in image, I want to visualize the result. To do so, I first reshape an RGB image to 3*size. The result of BSMC is the set of indices after clustering. So I change the value at the ...
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0answers
36 views

What is purpose of correlation kernel? IIs it high pass filter or low pass filter?

I am research about correlation kernel and I have some questions that need your help. Let see the pp. 3302-3303 in the paper: Changyang Li, et al., Robust Model for Segmenting Images With/Without ...
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0answers
78 views

Train a Cascade Object Detector in MATLAB

I am trying to train a cascade object detector in MATLAB using the built in functionality from the Computer Vision Toolbox. I’ve taken 500 photo’s of the sole of my shoe. Every photo is taken from ...
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1answer
67 views

Finding phase angle via FFT

I am using the FFT to calculate the amplitude and phase of AC cos signal. Regarding amplitude it gives me an accurate result but I get wrong result for a phase: 6 degrees instead of 36 degrees. My ...
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2answers
62 views

Verifying channel response identity

If $x[n]$ is input signal, $y[m]$ is output signal, $h[m]$ is impulse response of the channel, then the following relation holds $\lvert Y(\omega)\rvert = \lvert H(\omega)\rvert^2 . \lvert ...
2
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1answer
90 views

What is correlation kernel and compare with gaussian kernel

I read a paper that said about correlation kernel that defined: $$W(x-y)=(α/1+d(|y − x|))$$ where $α = (\int(1+d(y − x)dy)^{-1}$, $(d(|y − x|))$ is spatial Euclidean distance from the central pixel. ...
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2answers
44 views

shifting sequences using Matlab

I'm reading this book and I came across a function to shift sequences. Mathematically, $$ y(n) = \{x(n-k) \} $$ if $m = n-k$, then $$ y(m+k) = \{ x(m) \} $$ ...
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0answers
53 views

Deriving finite impulse response for polylogarithm

As a part of my research i have to use the following z-transform in matlab 'filter' function so as to derive the convoluted signal from the original one. $$\frac{1}{{\rm Li}_{k}(z^{-1}e^{-b})}$$ ...
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17 views

Region splitting and merge

I am currently working on an image trying to apply split and merge technique. My main problem is selecting the best predicate for my image. Furthermore, because the objects in the image are quite ...
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1answer
56 views

Find B given A and impulse response of B/A

Here is a small MATLAB function that computes B in B/A given A and the impulse response h of B/A ...