# Questions tagged [reconstruction]

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### How to reconstruct original signal from sampled signal?

My original signal as f1=2; f2=5; fs=100; Ts=1/fs; t=0:Ts:1; xt=cos(2*pi*f1*t)+cos(2*pi*f2*t); figure plot(t,xt) as shown below figure. and my sampled signal ...
0answers
31 views

### What is an analysis dictionary or operator in compressive sensing?

I am doing research on compressive sensing. I am new in this field. I read several papers regarding analysis dictionaries. Here are some papers that I have read so far: https://www.hindawi.com/...
1answer
36 views

### Difficulty absorbing Idea of interpolation?

I am trying to develop my understand of interpolation and signal reconstruction and uptill now i have understood that there are 3 commonly studied types of interpolation 1)Zero order hold ...
1answer
37 views

### piecewise-quadratic vs piecewise-cubic vs higher order polynomial interpolation?

There is a question available on DSP SE that mentions types of interpolation used for signal reconstruction but there isn't any mention about the difference between piecewise-quadratic,piecewise-cubic ...
1answer
74 views

### Zero order hold interpolation and Nearest-neighbor interpolation?

Is there any difference between Zero order hold interpolation and Nearest-neighbor interpolation I want to perform zero order hold interpolation in MATLAB,but there isn't any information about zero ...
0answers
9 views

### Three Projective Cameras in the Same “Projective Frame” - What Can I Do With This Info?

[I originally posted this under Mathematics, but I didn't get any replies. I thought I'd try here.] In Hartley & Zisserman's Multiple View Geometry in Computer Vision, in the chapter on trifocal ...
0answers
23 views

### Improving Vanishing Point Accuracy

I've been working for a while on 3D building reconstruction from old photos (c. 1904). In all of these cases, the cameras and buildings are long gone, making standard camera calibration impossible. ...
1answer
54 views

### Power Spectral Density Reconstruction

I am from an ML background and I am working on MP3 audio reconstruction and I have managed some amount of spectrogram reconstruction but I have noticed that the higher frequency end of the generated ...
0answers
30 views

### sampling using L1 optimization

As much as I understand the F should be the interval medians (correct me if I wrong), according to the next slide, where is also the Loss function defined: What I don't understand is the next note in ...
1answer
92 views

### Multiplying signals in discrete-time vs continuous-time

Given two discrete-time signals $a[n]$, $b[n]$ and its product $c[n]=a[n] b[n]$. The ideally interpolated, continuous-time version of $c[n]$ is \begin{align} c_1(t)&=\sum_{n=-\infty}^{\infty} a[n] ...
0answers
30 views

### Find the frequencies present when a non-sinusoidal wave is reconstructed

A 1.6kHz periodic (not sinusoidal) signal contains all its harmonics, both even and odd. The signal is sampled at 3.6kHz and ideally reconstructed. What frequencies are present in the output? I know ...
4answers
610 views

### Reconstructing a sine wave from an interval shorter than half its wavelength

I know that the function that I search is a sine wave of the form $$A \cdot \sin(x)$$ where my $A$ is unknown. I have samples of the sine wave at discrete points within an interval that's shorter ...
0answers
61 views

### 3D reconstruction of moving object

I am pretty new to the field of 3D reconstruction and overwhelmed by the large amounts of different methods. I am trying to find the correct method for my use case: Setting: I have a stationary ...
0answers
47 views

### Reconstruct a signal via continuous wavelet transform (CWT)

I want to use the continuous wavelet transform (CWT) to modify the amplitude of a signal in the frequency domain (in a specific frequency band) and then reconstruct the signal. I want to do it by ...
1answer
75 views

### Reconstruction using sinc

The signal that I produce above. What is the reason for it to slide to the right? In oversampling at Nyquist rate can I make like below picture ? do you think the signal i produced at nyquist rate is ...
2answers
396 views

### Sampling and Reconstruction of digital signal in Matlab

I'm trying to write a program in Matlab that samples (using Nyquist theorem) and recovers signal. However, I cannot write sampling part for sum of 2 signal. ...
2answers
206 views

### Types of interpolation used for reconstruction in DSP?

What are the different types of interpolation used in DSP for reconstruction of analog signal from discrete/digital signal I am able to somehow learn two types of interpolation 1st is "zero order ...
0answers
58 views

### STFT Reconstruction After Modification

Why do we want to minimize the difference between the two signals the original one and the modified one when all we want is the modified constructed signal? What is the purpose of making it the ...
1answer
56 views

### Can the Nyquist sample rate be extended to stochastic sampling?

It appears there are lots of questions here about Nyquist, and a few questions about stochastic sampling here. But I haven't found any that address quite what I'm after. This is the closest I've ...
0answers
167 views

### Lagrange Vs Sinc interpolation

I was wondering what is the practical difference between Lagrange Interpolation using Farrow Structure and Sinc Interpolation? Both require pre-computation of time offset coefficients using a lookup ...
2answers
174 views

### Proximal Gradient Method (PGM) for a Function Model with More than 2 Functions (Sum of Functions)

I am currently working in signal reconstruction. I am trying to develop an algorithm where the user can plug any constraint to the main objective function (let's say chi2, least squares). I was trying ...
0answers
36 views

### 2D IFFT implementation

I have a problem where I need to obtain 2D IFFT of a $81\times64$ signal. However, if we denote the reconstructed image $I_{m,n}$, its coordinates will be $M\times N$ but the k-space signal is sampled ...
0answers
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2answers
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### Discrete Wavelet Transform - Visualizing Relation between Decomposed Detail Coefficients and Signal

I'm trying to directly visualize the relation between discrete wavelet transform (DWT) detail coefficients and the original signal/its reconstruction. The goal is to show their relation in an ...
1answer
192 views

### How can you 'perfectly' reconstruct phase for transients in a modified audio absolute spectrogram?

I am currently working on the absolute spectrogram of an input audio signal. I am using non-negative matrix factorization to separate out the rhythmic components (bass drum, snare drum and hi-hat) of ...
0answers
145 views

### Perfect reconstruction of 2 channel filter bank

I am studying Perfect reconstruction of 2 channel filter bank for using Biorthogonal Spline wavelet for decomposing ECG signal. I am using Wavelets and Filter Banks By Gilbert Strang, Truong Nguyen to ...
1answer
322 views

### Reconstruction of a signal using an ideal DAC

I think I was able to do part (a) correctly, but now am stuck on part (b). I don't know how to approach this part or what is the theory behind it. My MATLAB code is shown below. Please let me know if ...
2answers
1k views

### Signal reconstructed using IFFT: amplitude scale larger than input

I am trying to test reconstruction of signal from IFFT. Below is the python program. I break the signal into overlapping windows and do FFT after multiplication with window function. Then I apply IFFT ...
1answer
288 views

### Inverse wavelet transform on wavelet coefficients

I have a data set which consists of Morlet coefficients for 7 channels in 18 bands. When I try to use inverse DWT in Matlab to get the raw data in time, using this code: ...
2answers
128 views

### In filtered back-projection, what does the $z$-axis in the reconstructed cross-sections represent?

The MATLAB code below is used for filtered backprojection (for $x$-rays). In this example program, it reconstructs an image of a simulated checker board, generated by the program. It uses Fourier ...