Signal Processing Stack Exchange
Signal Processing Stack Exchange

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1500 questions
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3 answers

Autocorrelation in audio analysis

I'm reading up on Autocorrelation, but I'm not sure I understand exactly how it works and what output I should expect. Am I right in thinking that I should input my signal to the AC function and have a sliding window input. Each window (of 1024…
XSL
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What methods can be used to identify and remove echo from an audio system?

Background I am designing a system that will have a single small microphone and speakers for use in a phone type setting. Easiest example I can give is a Skype conversation where you are using your computers speakers and a desktop microphone. I am…
Kellenjb
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How to build a phase shifter with arbitrary phase shift

Fred, a DSP engineer, goes to his favorite DSP store to do some shopping. Fred: Hi, I'd like to buy a phase shifter. Shop assistant: Hmm, what exactly do you mean? Fred: Well, you know, if you put in a sinusoid like $x(t)=\sin(\omega_0t)$ you get…
Matt L.
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16
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13 answers

Deconvolution of 1D Signals Blurred by a Gaussian Kernel

I have convolved a random signal with a a Gaussian and added noise (Poisson noise in this case) to generate a noisy signal. Now I would like to deconvolve this noisy signal to extract the original signal using the same Gaussian. The problem is that…
user1724
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Getting loudness of a track with RMS

I'm trying to calculate the loudness of an audio track I have stored in a buffer. The buffer contains PCM data of the signal and I want to get how 'loud' it is by using Root Mean Squared. I assume I can do this in the time-domain instead of having…
XSL
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5 answers

How to write lowpass filter for sampled signal in Python?

I have some signal that sampled each 1 ns (1e-9 sec) and have, let say, 1e4 points. I need to filter high frequencies from this signal. Let say I need to filter frequencies higher than 10 MHz. I want that for frequencies lower than cutoff frequency…
Alex
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16
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4 answers

Extracting frequencies from FFT

I performed 512 point FFT on a signal. I got another set of 512 Numbers. I understand that those numbers represent amplitude of the various sine and cosine waves having different frequencies. If my understanding is correct can somebody tell me how…
gpuguy
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Is there such a thing as band-limited non-linear distortion?

So if you generate a square wave by just switching a signal between two values, at sample boundaries, it produces an infinite series of harmonics, which alias and produce tones below your fundamental, which is very audible. The solution is…
endolith
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Fast Fourier transform- non-integer number of cycles in the FFT aperture

There are a few excellent discussion threads and answers on this site (eletronics.se) on the theory of Fourier transforms. I tried implementing the same in a simulation tool (MS Excel :)). I have a few interpretation and implementation issues…
Vaibhav Garg
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What is the difference between feature detectors and feature descriptors?

What is the difference between feature detectors and feature descriptors? Which among these are detectors and which are descriptors: Harris, SURF, Min Eigen, FAST, SIFT, BRISK
Jayesh Parmar
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Fitting new images from a SVD/PCA calculation

I'm trying to replicate the ideas from the Eigenface page on wikipedia. From a hundred sample images represented by a data matrix $\bf X$ (where each image flattened to a vector of length $n$, thus $\bf X$ is a $100$ by $n$ matrix), I've computed a…
Hooked
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3D reconstruction of an image based on depth of intensity levels?

Is there anyway of segmenting objects based on how far they are from the viewer? Can color values assess this sort of a thing for us? How will intensity levels help in determining how far the object is from the viewer? Another image:
vini
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What distance metric can I use for comparing images?

I usually use the mean squared error (MSE) or peak signal-to-noise ratio (PSNR) to compare two images, but this isn't good enough. I need to find a formula that returns a very big distance between an image A and its pixellated (or blurred) version…
lezebulon
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Image Reconstruction:Phase vs. Magnitude

Figure 1.(c) shows the Test image reconstructed from MAGNITUDE spectrum only. We can say that the intensity values of LOW frequency pixels are comparatively more than HIGH frequency pixels. Figure 1.(d) shows the Test image reconstructed from PHASE…
sagar
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How to extract vocal part from stereo audio signal?

I'm now processing MP3 file and encounter this problem. My MP3 is stereo encoded. What I want to do is extract vocal part for further processing(whatever mode of output signals, mono or stereo are both OK). As far as I know, audio is encoded into…
Summer_More_More_Tea
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