Questions tagged [matlab]

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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39 views

“plot” command for continous time signal in matlab?uses interpolation?

We know digital computer cannot deal with continuous time signals directly. But then how MATLAB "plot" command works? Does that uses interpolation technique to show an apparently continous time ...
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Image processing and compression

Have two quations! related to this image Is it posible to identify any spatial domain features in the frequency domain? My understanding: what i read around they are mostly the same as spatial ...
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How to get Spectrogram after fft in matlab?

I have many EEG signals which record at 100 Hz. I use FFT on them with fft Matlab toolbox. Now I wanted to get a Spectrogram. As I searched and read a lot, I figure that I should window my signal and ...
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Help with Audio Signal noise removing using FFT and IFFT in Matlab

I dont understand why my modified fft of a audio signal returns complex values after ifft. I modified my signal by zeroing out all the unnecessary freq. FFT: Fast fourier transfrom IFFT: Inverse ...
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Convolution introduces NaNs

I am performing convolution in MATLAB using the built in conv function. I am convolving an impulse response (length 500 samples) with an 1800 sample long input ...
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2answers
54 views

aliasing folding phenomena in frequency domain matlab

Hello i am trying to create the folding phenomena of undersampling in matlab, When i undersample the sampling frequency is 135 less than the Nyquist frequency for 70 Hz signal ou will see that it is ...
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Standard deviation of Morlet wavelet's Fourier transform

MATLAB has the complex Morlet Wavelet in the following form: $$\psi(t) = \frac{1}{\sqrt{\pi f_b}}e^{\frac{-t^2}{f_b}}e^{j2\pi f_c}$$ I arrived at its Fourier transform as shown below (another ...
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1answer
25 views

Solving LASSO (Basis Pursuit Denoising Form) with LARS

I'm now working on using LARS (Least Angle Regression) algorithm to solve a LASSO problem in Basis Pursuit Denoising form like: \begin{align*} \quad && \arg \min_{\beta}{\left\| y - X\beta \...
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Visualizing the “frequency shift” theorem in FFT

I was trying to visualize the frequency shift theorem in MATLAB, which states that if the Fourier transform G(f) is shifted by a constant $f_o$, its inverse transform g(t) is multiplied by $e^{j2\pi ...
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Spectral kurtosis on non-stationary signal

I posted a question some weeks ago I still have not found an answer to. I updated the old question and am hoping someone could help. Link: Varying speed of shaft Spectral Kurtosis
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Discretizing my continuous system in Matlab

I was hoping someone could help me with conducting my discretization in MATLAB. I have a linear system with known data: sampling interval $T$, system matrix $\mathbf{A}$, input matrix $\mathbf{B}$, ...
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How do i calculate the accuracy of an algoruthm?

I'm doing research on an machine learning image processing algorithm (segmentation algorihtm)i.e. computer vision performs when an image takes as an input and objects in an image are segmented and ...
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Show Equivalence Between Multiplication in Time Domain to Convolution in Frequency Domain

My goal is to compute the Fourier of the product between two discrete time signals, y1 and y2. This can be done by computing the convolution between the fourier transform of y1, f1 and the fourier ...
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Adjust signal to account for increase in gain

I have 2 signals recorded at 2 different locations along a beam. I excite one end of the beam, and measure the signals at 2 different points. Within the system I have pre-amp and post-amp gain on ...
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Adding a DC offset to a pre-emphasized signal

I'm trying to implement some speech recognition on low-end microcontrollers. so I have to rewrite and optimize some methods into C for embedded work. the audio is sampled from an AGC preamplifier ...
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Residual error when setting measurement matrix in compresssive sensing

I have an issue when implementing compressive sensing to recover sparse vector. Assume I have sparse vector $x$ of length, for example, $(256,1)$. $x = [x_1,x_2,.....x_{256}]$. This vector is ...
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What steps and methods are recommended to process various signals of a IMU sensor [closed]

I'm new here because I'm making my degree final project. See more my profile for more information. I want you to recommend me what are the tools to analyse the sampled signals and process them in ...
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Varying speed of shaft Spectral Kurtosis

I want to perform Spectral Kurtosis (Kurtogram) on 10-second vibration signal of 25.6 kHz sample rate, where the shaft is varying in speed. Will a preprocessing step of resampling the signal be ...
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Why Cross-correlation work better than Generalized Cross-correlation GCC-PHAT in MATLAB?

Fs = 192000; t = 0:1/Fs:(0.01-(1/Fs)); F1 = 10000; x = 1*sin(2*pi*t*F1); nSamplesGausswin = length(t); w = (gausswin(nSamplesGausswin))'; s = w .* x; this is ...
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Removing Noise from time across signal data

I am new to the field of signal processing. I have sensor data (Impedance across time), that output is like this. On the right side, I have a noisy signal portion in my data, marked by the red block....
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28 views

Adjusting coefficients of a LP and HP filter for a new sampling rate

I am pretty new to DSP and try to undertand some concepts and the relations between them. I currently learning about the Pan-Tompkins algorithm and trying to recreate it in Matlab (Pan–Tompkins ...
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41 views

MATLAB- Add Envelope to Sound Signal

I’m in the process of making a convolution reverb and I’m trying to add an envelope to my impulse response signal and plot it in order to change the RT60 of my sound signal (Just a song). I’ve looked ...
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Unexpected Results in Rank Transform Based Disparity Estimation

I am applying a normal rank transform of size 7 x 7 to the right/left shifted images in order to obtain their disparity map using a typical block matching algorithm in MATLAB. My code to obtain to the ...
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2answers
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Explanation for the quantization matlab function

I found this code on quantization on page 314 in the book Modern Digital and Analog Communication Systems by B.P.Lathi and Zhi Ding. I can understand only half of the code. Please, someone, help in ...
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How to put specific frequency in a specific bin in frequency domain?

I have eight tones as represented by f, and I want to the distance between every two tones is different as shown in the figure, I have the frequency spacing, but I need to put the tones properly, and ...
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28 views

bandwidth between the signal and the channel

I have a signal with a bandwidth $B=4$ kHz and the bandwitdh is between $6$ kHz and $10$ kHz. I want to transmit this signal in a channel with bandwidth $B'=4$ kHz but for the channel the bandwidth is ...
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1answer
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Factored form vs partial fraction form?

I have already understood partial fraction and here is link for my relevant DSP SE question Finding inverse z transform for two sided ROC? But now i want to know, is there any difference between ...
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How to compute the DFE based MMSE equalizer FF and FB coefficients in a non adaptative way?

I seek your assistance, I am reading the Proakis 5th edition and I came across a paragraph explaining the tuning of DFE filters, i.e, how to compute the FF(FeedForward) and FB (Feedback Filter) ...
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84 views

Converting PSD to Time Domain Signal

I am currently using MATLAB and I'm thinking if I can reconstruct PSD back to time domain signal using MATLAB's ifft. I found a link in solving this problem but it's in Phyton and when I tried it in ...
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113 views

How to Reduce Phase Lag Caused by Kalman Filter

Background I have been developing a system using a moving robot with a distance sensor against another robot. I want to control these robots by estimating relative velocity and acceleration derived ...
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49 views

Least square error channel estimation in the presence of AWGN noise

I want to implement Least Square (LS) channel estimation method in the presense of AWGN noise in MATLAB. $y(n) = x(n) * h(n)$ $Y(k) = X(k)H(K)$ Y(k) is the received signal in frequency ...
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1answer
121 views

Evaluating the continuous Fourier transform of a constant, and matching it up with the FFT result

I am following my optics textbook (Optics, by Eugene Hecht), throughout which are given various exact analytical results for the diffraction patterns that result from light passing through differently ...
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33 views

Matlab DFFT phase shift or data problem

Good day, I found a problem with calculating DFFT in Matlab. I have 1200 signals and for each I calculate FFT separately and then plot them together. it is a wave signal (simulation) propagating with ...
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43 views

Why are MATLAB and matplotlib spectrogram value different?

I'm doing a signal processing to put data into my neural network. I noticed a difference between MATLAB and Python ...
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1answer
25 views

The complexity of such function run in Matlab

The below function is representing an algorithm, so how can I get its complexity? I don't mean the time of running by using the tic .. toc, I mean how many operation (Additions and multiplications) ...
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35 views

How to measure quality of an audio/music recording compared to the original

I have 3 wav files: The original recording of a viola note A noisy re-recording of the original clip A different noisy re-recording of the original clip I'm looking for a way to show which of the ...
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1answer
38 views

On the Use of OMP Algorithm to Estimate Sparse Vector

As known, Orthogonal Matching Pursuit (OMP) Algorithm is to recover the sparse channel after convolution with another vector. But when I implement that in MATLAB, I don't get the sparse vector ...
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1answer
35 views

MMSE- Channel estimated based - DFE Equalization

For HF ionospheric channels ( frequency range 3 up to 30 MHz), I Want to make channel equalization in time domain, using MMSE criterion. I have to do it using the channel estimation. I have some ...
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2answers
43 views

Finding inverse z transform for two sided ROC?

I have a z transform $Y(z)=(z^2-z) /(z^2+1.3z+0.3)$ In this case i have two poles ,one at -0.3 and one at -1.0 I want to find inverse z transform of Y(z) Following is my matlab code: ...
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Wavelets: Manipulate its phase and reconstruct

Usually when I read about wavelets in image processing, the authors tend to make use of its coefficients and rebuild based on certain criteria, for example de-noising an image where you usually filter ...
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1answer
31 views

Producing images with subpixel shift in region of interest

Let's say for a zebra image, and at certain pixel location, I would like to makes it "vibrate/warp" to and fro in horizontal direction at a certain frequencies in a sequence of images of time ...
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1answer
30 views

Wrong output for phase demodulation

I tried to plot phase demodulated signal and original message signal but there is a significant difference between magnitudes of the message and demodulated signal. I have attached the code and the ...
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41 views

Cross power spectral density (CPSD) comparison between signals

I want to compare various signals with Matlab's CPSD to identify shared frequency components. (If there's a better method, I would like to know!) I have 3 signals, A, B, and C. B is pure noise while ...
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1answer
21 views

Doubt in Frequency Modulation code

While searching for something FM, I came across this code. I am not able to understand a particular line of code. I have written a comment against that line of code. ...
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2answers
51 views

What is Magnitude and Phase actually represents in Fast Fourier Transform?

When we reconstruct the image from its magnitude only using Inverse Fast Fourier Transform, then why the resulting image looks nothing like but the original image? Can someone please explain me in ...
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1answer
72 views

Determing inverse Z-transform using impulse response?

In Matlab there is a command iztrans for finding inverse Z-transform. But how can we find inverse Z-transform using impulse response? The Matlab command ...
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56 views

Frequency modulation in MATLAB

I am trying to frequency modulate a cosine signal(for assignment). I have written the following code but not getting the required output. ...
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52 views

Stabilizing the inverse transform of a system

Currently I try to understand an unknown mechatronic system. I used white noise as an input signal and measured the output of the system. Then I estimated a 2nd order transfer function (Output/Input) ...
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1answer
41 views

How do I create a polar plot from a multi-channel sound file?

I have a multi-channel sound file from a microphone array. I want to get the polar plot in Matlab in order to get the directivity patter of the sound source. How do I do this? I did the FFT on the ...
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Rayleigh multipath fading channel in Matlab

I have to calculate eigen values of covariance matrix of Rayleigh multipath fading channel. The exact value should depends on delay spread and subcarrier spacing. I am able to find eigen values but ...

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