Signal Processing Stack Exchange
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Moving average vs. Moving median

I have read in many places that Moving median is a bit better than Moving average for some applications, because it is less sensitive to outliers. I wanted to test this assertion on real data, but I am unable to see this effect (green: median, red:…
Basj
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Determining how similar audio is to human speech

While looking for an answer to this problem, I found this board so decided to cross post this question of mine from Stack Overflow. I am searching for a method of determining the similarity between an audio segment and a human voice, which is…
Jeff Gortmaker
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Discrete Fourier transform symmetry

I was reading the chapter on discrete Fourier transforms in Lyons' book -- Understanding Digital Signal Processing -- and could not understand the last paragraph about symmetry. There’s an additional symmetry property of the DFT that deserves…
someguy
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What is meant by 20 dB signal-to-noise ratio?

I'm reading a paper in which a discrete signal $$x(n) = s(n) + w(n)$$ is considered. $s(n)$ is a known, deterministic series, and $w(n)$ is white noise with zero mean. The authors write that signals were generated with an SNR of 20 dB What does…
Anna
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What are the basic categories of operations performed on audio signals to create interesting sounds?

I don't know if this question will make sense as I'm very new to dsp. In my limited foray into audio dsp I've come across: Frequency Modulation Amplitude Modulation Additive Synthesis Subtractive Synthesis My question is: are these the main…
kiman
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Tutorial on 2nd generation wavelets (with lifting)?

For some denoising and deconvolution experiments, I'd like to apply a 2nd generation wavelet transform (using lifting steps) to images. I know that there are several implementations available, but most of them use Matlab, while I want to work in C++…
sansuiso
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How to estimate a transfer function from a magnitude-only frequency response?

Given an arbitrary frequency response, what signal processing methods might exist that could guess, estimate or determine a transfer function (pole and zero constellation) which gives a "reasonably good" approximation (for some given estimation…
hotpaw2
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Difference between power spectral density, spectral power and power ratios

What 'exactly' is power spectral density for discrete signal? I was always under the assumption that taking the Fourier transform of the signal, and then the ratio of desired frequency range magnitude over the entire frequency range gives the power…
anasimtiaz
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Auto-focus estimation?

What kind of analysis might be used on sets of 2D monochrome image matrices or bitmaps to estimate or compare their relative quality of being "in focus"? Is there an efficient way of computing a scalar metric on something like overall contrast,…
hotpaw2
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Why does my stop-band filter attenuate other frequencies?

Here is my code for a two-toned signal, where I use a stop-band to remove the higher tone and then plotted the before (in blue) and after (in red) in the frequency domain after convolving my signal with the filter coefficients. If you put this code…
Zaubertrank
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Why do I see ringing in the output of a digital filter with a narrow transition band?

I am doing some 'extreme' eq for spectral mangling type effects with audio. Im using brick wall filters, and very narrow band pass and reject filters (vst plugins), and I'd like to know if there's anything I can do about the pre/post 'ring' with the…
Dale Newton
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What kind of filter is that? Is it IIR?

I am trying to answer the following question: Is the system described by equation: $$y[n]=0.5y[n-1]+x[n]-0.5x[n-1]$$ an IIR filter? My answer is yes. Thank you
Black Yasmin
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When Is a Kalman Filter Different from a Moving Average?

this thread asks when a discrete time Kalman filter is better/different from a simple moving average of the observations: Why use a Kalman filter instead of keeping a running average? there's no definitive answer. can someone give a definitive…
user24823
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What statistic is used to determine presence of a signal in noise?

This is a detector problem I believe: I am being stumped by what appears to be a simple problem. Basically, I have a band of interest. If signal energies exist within this band of interest, then I perform operation X on my signal. My problem is…
Spacey
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Image Denoising with Better Edge Preservation

I have the input image : and the output of vein detection for the leaf using a Gabor filter, but the output is really noisy: I tried using Total variation denoising however the results are not good: However I don't want to loose the fine details…
vini
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