# All Questions

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### Implementation QPSK modulation code in Marlab

I am trying to implement modulation schemes for a codebook. I have written smth for QPSK, but I am not sure If it is correct to write in this way ...
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### Definition of MIMO (Multi-input Multi-output ),does this output mean antenna or transmitter?

I want to ask the definition of MIMO(Multi-input Multi-output ) If there are one transmitter and one receiver,each of them has $N$ antennas,$N >1$. So i can say it is a MIMO system. But if now i ...
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### DCT vs DFT why do we need/want phase?

Why do we use complex exponentials in the Fourier transform, why do we want the phase part? As opposed to in DCT where there is no phase and only magnitude? Moreover, what does this phase concretely ...
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### What is the difference between positive matrix coefficients and negative matrix coefficients of an audio?

I have turned an audio file into an one dimensional array by using audioread function in matlab and found several positive and negative fractional coefficient values.What is the basic difference of ...
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### (FFT) Is it good practice to ignore each bin's phase when characterizing a signal

I have been recently working with the FFT and realized that each frequency within a bin corresponds to a phase. I understand why a phase that corresponds to each frequency is needed because it allows ...
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### Aliased Signal's Frequency

So I have an incoming signal of 137.9 MHz and a sampling frequency of 1.4 MHz. Once sampled how do I calculate the aliased signal's new frequency? Bandwidth is 38 kHz with a subcarrier of 2400 Hz if ...
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### Signal Header:Physical Min is not less than Physical Max- after opening EDF file on the viewer

Whenever I open an EDF file on the Case Western Research University's EDF Viewer Application, I get a Scaling Warning-"Signal Header:Physical Min is not less than the Physical Max ". I am reading ...
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### What does imaginary Component of a bin's phase in the Fourier Transform mean?

I have been recently working with the FFT and realized that each frequency within a bin corresponds to a phase. This concept I have no problem with because if you wanted to construct the summation of ...
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### How can single low-resolution have multiple high-resolution versions?

I'm trying to prove the fact that the super-resolution problem is ill-posed problem. As having a single low-resolution image we can generate multiple high-resolution images. which also known by ...
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### psd in matlab, problem with the coefficient $\frac{1}{2\pi}$

Using the fft to mimic the Fourier Transform I have this question. The definition that I use for the PSD $S(f)$ is: $S(f)=\frac{1}{2\pi}\int_{\infty}^{\infty}exp(-i\tau2\pi f)r(\tau)d\tau$ where r(t)...
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### Calculation of PSD using Hamming Window

I have 600000 time domain Data. I want to calculate the psd using that data. But I want to use hamming window to my data set and overlapping them to get a smooth psd vs. frequency graph. I need a ...
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### What is the significance of y-axis in Lomb-Scargle Periodogram?

What does the y-axis of Lomb-Scargle periodogram represent? Periodogram obtained by Fourier transform contains information about the original data's amplitude, but the so-called "Lomb-Scargle power" ...
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### Classifier for detecting abnormal noise using FFT

As a simple machine learning application for quality evaluation, I want to detect abnormal sound in a product. A good product would make a signature humming sound, a bad product might make noises due ...
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### Help to identify this impulse/autocovariance

I have attached a picture of an autocovariance over a single lag. To my (inexperienced) eye this looks like some kind of impulse response but I am unable to identify the function. The picture is taken ...
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### Extract feature points and visualize on 3d Mesh

I'm Coding with python, I have a 3d Model mesh, and I'm trying to get features and descriptors So I was able to get Zernike moments using mahotas library which gives a vector of data, I have to ...
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### What is matched filter in QPSK signal?

Consider we have received a QPSK signal. We than make I (In phase) and Q (quadrature component) which I understand is nothing but multiplying the received signal by the cos(2*pi*f) and -sin(2*pi*f) ...
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### Number of microphone limitation for Spherical Harmonics based DOA estimation

I am following this book "Theory and Applications of Spherical Microphone Array Processing", as well as this paper on DOA estimation "Eigenbeam-ESPRIT for DOA-Vector Estimation". My dataset is ...
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### What does $I_{seg}$ in 3GPP TS 38.212 version 15.2.0 Release 15 represents?

I'm working on 5G NR, whereby on reading Code block segmentation and code block CRC attachment given in Subclause 5.2.1 of 3GPP TS 38.212 version 15.2.0 Release 15. What does $I_{seg}$ represent?