Signal Processing Stack Exchange
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How do window size, sample rate influence FFT pitch estimation?

I am trying to create a pitch-detection program which extracts the frequencies of peaks in a power spectrum obtained from an FFT (fftpack). I am extracting the peak frequencies from my spectrum using Quinn's First Estimator to interpolate between…
willpett
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reconstruction filter - How does it actually work?

I'm trying to form my own understanding on the religious war around using 192kHz as a sampling rate for playback (the Internet seems to have a wealth of material on both sides). I'm struggling to understand how reconstruction filters work. The…
user1202136
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What is the meaning of the DFT?

Possible Duplicate: Real Discrete Fourier Transform What is the most lucid, intuitive explanation for the various FTs - CFT, DFT, DTFT and the Fourier Series? Discrete-time Fourier transform I read about the Discrete Fourier Transform. I…
John Smith
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Auto Detection of Rotation Angle on Arbitrary Image with Orthogonal Features

I have a task at hand where I need to detect angle of an image like the following sample (part of microchip photograph). The image does contain orthogonal features, but they could have different size, with different resolution/sharpness. Image will…
BarsMonster
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Downsampling lowpass filter for audio: FIR or IIR?

I'm working on a real-time audio processing project in which I have to downsample a 44.1 kHz to a yet-to-be-determined lower sampling rate essentially for reducing computational complexity. I'm looking for a decent downsampling filter, and I found…
Phonon
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How does the $\mathcal Z$-transform's "region of convergence" work?

I'm a novice in DSP and I have few doubts regarding the $\mathcal Z$-transform and its region of convergence (ROC). I know what a $\mathcal Z$-transform is. But I'm having trouble with understanding the ROC. First of all I have some confusion with…
Ant's
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What is Frequency Resolution?

Im trying to tackle the following problem while still not having a firm idea on what "frequency resolution" means : Suppose we sample a continuous time signal with sampling period Ts = 1/2000, and then use a window of length 1000 on the resulting…
Αποστολης Καρασμανογλου
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How to implement a gradient based Hough transform

I am trying to use the Hough transform for edge detection, and would like to use gradient images as the basis. What I have done so far, given the image I of size [M,N] and its partial derivatives gx, gy, is to calculate the gradient angle in each…
Jonas Due Vesterheden
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FFT vs DFT Run Time Comparison (Complexity Analysis) in MATLAB

So we were given an assignment to plot the time taken by the FFT algorithm by MATLAB and a DFT algorithm written by me in MATLAB.G The expected output should have been the DFT algorithm following the O(n^2) complexity, however when I plot the output…
Abhinav Jain
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How to segment phone call audio into silence/non silence?

My problem is that I don't know the energy of the background noise, so I can't just threshold the energy. The processing is done in real time, and I have about 500msec to decide. Ideally, I'd want quiet consonants considered non-silence.
Michael Litvin
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What Is the Difference Between PCA and Karhunen Loeve (KL) Transform?

I have been reading about Karhunen-Loeve (KL) transform. I see that when it is used to reduce dimension the procedure is identical to PCA, that is, for both methods the covariance matrix of the data is constructed, and then the eigenvectors are…
Roger Figueroa Quintero
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Zero Crossing of a Noisy Sine Wave

I'm trying to find the zero crossings of a sine wave to transform the sine wave into a square wave. The only problem is that the sine wave is noisy, so I'm getting lots of jitter and false zero crossings. Can anyone recommend any simple psuedocode…
Kevin Nasto
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Implementation of Wikipedia Equation for the DFT

I was writing a simple fourier transform implementation and looked at the DFT equation on wikipedia for reference, when I noticed that I was doing something differently, and after thinking about it felt that the wikipedia version must be wrong…
Nimitz14
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Relative merits of fixed point vs floating point computation?

I have a digital signal processing system that operates on a fast x86 machine using double precision floating point numbers. It occurred to me that I am not really using the huge dynamic range of the floating point representation -- all quantities…
nibot
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Detecting direction of sound using several microphones

First of all, I've seen a similar thread, however it's a bit different to what I'm trying to achieve. I am constructing a robot which will follow the person who calls it (3D sound localization). My idea is to use 3 or 4 microphones - i.e. in the…
Max Walczak
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