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1500 questions
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Frequency Analysis (DFT / FFT) of a Signal Without a Constant Sampling Frequency (Non Uniform Sampling in Time Domain)

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 $10000\times 2$ double variable. The data is available…
Pedro
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How can I measure noise and sharpness of an image?

I'm working on a project which ranked some images based on quality. For this project, I want to figure out the noise and the sharpness from a image. To calculate the noise (from a CCD-Sensor) I think I can calculate the average noise from a image.…
501 - not implemented
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How/why are the $\mathcal Z$-transform and unit delays related?

The $\mathcal Z$-transform uses the same notation as the unit delay $z^{-1}$, but in $\mathcal Z$-transform $z$ is a complex number. What's the relation between the $\mathcal Z$-transform and the unit delay concept? Also, is there a complex number…
mavavilj
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Audio fingerprint questions

I am developing an application that requires audio fingerprints. I have been reading a lot of articles and PDFs, now i think i have gotten myself confused. Based on my present understanding, I have some questions After decoding the audio to its…
Kennedy
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Is there a strategy for discrete control of a system with dynamics near sample rate?

I'm trying to control a system where the controller sample rate is physically fixed and the plant has significant dynamics on the same order as the sample rate. I understand that one would prefer to have the sample rate considerably faster than the…
tkw954
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What is difference between terms $X(j \omega) ,X(\ e^{j \omega })$ and $ X(\omega)$?

While studying frequency transforms ,I get confused with the terms like $X(j \omega) ,X(\ e^{j \omega })$ and $ X(\omega)$ ,where $ \omega = 2 \pi f $. So what is the difference between them ?
pandu
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Is my transform the essence of DFT?

I'm someone just learning DSP, and want understand its essence. My transform is the simplest possible. Input signal is just one frequency: $256\textrm{ Hz}$. Sampling frequency is $2560\textrm{ samples/sec}$, so $10\textrm{ samples}$ correspond to…
George Theodosiou
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Can you turn a square wave into a sine wave using a low pass filter?

And if it could, would it make the sound of the square wave thinner than before because of losing its harmonics?
Mark
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How to de-noise raw sound data

What techniques/algorithms can I use to remove noise from a raw recording of sound (voice)? The purpose is to get a smoother graph (removing the "jaggedness"). What I have tried was to average-out small deviations by using the surrounding two…
slashmais
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Implementing Convolution in Frequency Domain?

Suppose, we have a bitmap image represented as a 2D integer array, int [,] image2D; whose FFT is Complex[,] fftImage2D; Suppose, we have an kernel represented as a 2D integer array, int [,] kernel2D; whose FFT is Complex[,] fftKernel2D; We know…
user18425
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Estimating attenuation using sliding windows

I am looking for an algorithm to measure attenuation of a discrete signal $s[t]$. Starting at the beginning of the signal sequence, is it possible to compute either sliding DFT or Gabor transform windows and use the amplitude and phase information…
Nicholas Kinar
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Blending Artifacts in Photo Stitching

I am working on a photo stitching application that uses multi-band blending. I need to get rid of unpleasant edges appearing at some places: Here is the area of overlap (left - new image added to the mosaic, right - current mosaic contaning pixels…
Libor
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What's the Difference Between LMS and Gradient Descent Adaptation?

I found algorithms that seems the same to me, but they are described with different names (in field of adaptive filtering). For example: LMS - least-mean-squares seems to be GD - stochastic gradient descent Often the stochastic gradient descent is…
matousc
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Bandwidth expansion by computing missing harmonics in music?

In old recordings or highly compressed audio files (lossy), the higher frequencies are lost, and we hear a distinctive muffling effect. (Just like if the song was played through a wall) Is it possible to compute the missing harmonics using any…
Bloc97
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Intuitive interpretation of Fourier transform in beamforming

When applying Fourier transform in time domain the signal will be carried to frequency domain. And when we apply Fourier transform in spatial domain the signal will be carried to directivity domain. $$ D(\theta) = \sum\limits_{n =…
Kadir Erdem Demir
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