# All Questions

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### Do all Harmonics of a periodic sound start from a 0 base

I've been thinking about additive synthesis and I'm wondering if all sounds begin at (theoretically) phase 0?
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First post, and this isn't my field of study, but I'm giving this a go anyway: My latest endeavor is to use a bit of DSP magic to match up various pairs of headphones, at least in terms of their ...
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### Does scaling property imply superposition?

For a system to be linear,it follow the principles of scaling and superposition.Does scaling imply superposition?If so why are two different conditions given for linearity?If not can u specify an ...
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### what is the preffered data and FFT length for blackman harris window for improving Accuracy due to ENBW Consideration of window?

for Rectangular window if data length is 1K then FFT Length Should be 1K FFT only because ENBW of rectangualr window is 1.0 but for Minimum 4-Sanple BlackmannHarris window is 2.0. so for improving ...
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### Forward and backward filtering

I have an input sequence $x(n)$ and impulse sequence h(n) = \begin{cases} 0 & \quad \text{when } n = 0 \\ .239052 & \quad \text{when } n = 1 \\1.3357\exp(-0.650286n) & ...
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### Which anatomical model to use as “ground truth” for validating an MRI segmentation method?

I am research in brain segmentation task that classify a brain in to 3 classes : White Matter, Gray Matter and CSF. To validate my method, I used Dice Coefficient that compare my result and ground ...
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### Python bandpass filter - singular matrix error

I've been trying to design a bandpass filter using scipy but I keep getting a LinAlg Singular Matrix error. I read that a singular matrix is one that is not invertable, but I'm not sure how that error ...
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### How to use wavelet decomposition for feature extraction (of fMRI images)?

I have a dataset consisting of fMRI images (from mice) which are divided into 4 groups (different drug dose levels applied). Each fMRI image is 4D, that means each voxel is a time series. For each ...
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### Image segmentation: Grabcut versus Level-set

Checking the literature about image segmentation, if I am not wrong, there are two main approaches: Variational approach e.g. level-set optimization in Chan-Vese Combinatorial approach e.g. using ...
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### 2D Log-Gabor implementation in C++?

Is there anywhere out there a 2D log-gabor implemenataion in C++? I have been searching all day and I just couldn't find a normal implementation. I just want to test the filter in my prgoram and I ...
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### Any good C# library for signal processing?

Does anyone can link me to a good C# DSP library? I saw some good C++ libraries but I don't have much with C++. Is there any way to wrap them ? My main porpuse is to apply some filters(Lowpass, ...
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### WiFi and the sampling rate of spectrum analyzer

I'm trying to understand the correlation between RF analyzesrs and WiFi. Looking at the device's datasheet I see that it has a sample rate of (max.) 100msec. [to my understanding, the device can ...
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### applying single pole filter to simple signal

How to apply single pole filter to simple signal fs = 500; ts = 1/fs; t = 0:ts:1-ts; fc = 50; S = cos(2*pi*fc*t);
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### Zero Cross Rating synchronization

I send some pure sinuses that are representing bits. I found that after some bits the system is losing synchromization so for example: if I want to catch a 13Khz sinus I get 12.8K. I use ZCR to ...
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### Invariances in Neural Networks

I have a question about invariances in neural networks. In general, neural nets with enough layers can learn arbitrarily complicated nonlinear functions. Therefore, it's not hard to understand how ...
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### Correlation of an image in the Fourier Domain

I have been reading up on correlation in the frequency domain, and I just had two questions which I could not find in the book I was reading nor online: [1] So correlation is the same as a normalized ...
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### FIR filters always linear?

Are Finite Impulse Response filters always linear? I looked at https://en.wikipedia.org/wiki/Nonlinear_filter and its says that if a filter does not obey linearity, it is non-linear filter. Thats ...
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### Template matching for object recognition and pose estimation

I am currently reading a series of articles from Hinterstoisser about template-based real-time detection of texture-less objects and estimation of their pose. It is the series of articles that ...
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### What does “A Target with Zero Doppler” Mean?

I have seen several references to target at zero Doppler and some simulations that command users to place a target at zero Doppler. I know that when a target is flying tangential to the signal the ...
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### What is Single pole filter?

Can anybody tell me why do we use single pole filter? And may be an example of Single pole filter in matlab. Good literature recommendations are also welcomed.Moreover, that would be good if anyone ...
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### Estimation of latency for music played through a speaker

I need to estimate the latency for a music source that is played through stereo speakers but also transmitted wireless to the recipient. The music needs to be synced at the recipient by using a ...
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### Advice on autocorrelation via FFT

I have been creating an application in Java that transforms an audio signal and writes it to a midi file. At first I tried using autocorrelation to find the fundamental frequency. However, I have ...
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### Matlab fspecial disk: Algorithm reference or algorithm logic

I'm trying to figure out how the fspecial function works to create a discrete disk in Matlab. This function is an averaging filter that arises in an image processing environment. The Matlab algorithm ...
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### Advantage of using FIR Polyphase Decimator over just computing FIR output every D samples

Let's say you want to implement an FIR filter $h[k]$ with $L$ taps and downsample the output: $v[k] = x[k] * h[k]$ $y[m] = v[kD]$ The "naive" way would be to compute all the samples of $v[k]$, then ...
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### Resampling data from impact testing

I have asynchronous data from two different data acquisition systems (one for the impact hammer and the other from accelerometers). I am using pwelch and cpsd in matlab to calculate the FRFs however ...
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### Sound Characterization [on hold]

For the last 6-7 months I have been working on a small project attempting to get sound-recognition to work on a raspberry pi in real time. My last iteration of sound recognition was centered around ...
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### How to estimate the power spectrum in yule walker method?

I'm trying to estimate the power spectrum using yule walker method in C++ . After finding the coefficient ,how to estimate the power spectrum ? Example: I got the coefficient up to 30 ...
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### Difference between a calculated envelope and the actual magnitude envelope?

The magnitude of a given signal is also an envelope (?), but usually envelope is used to refer to computed techniques (https://en.wikipedia.org/wiki/Envelope_%28mathematics%29) for finding an envelope ...
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### Frequency response of a (rectangular) integrator

A very simple question which can't really figure out: I have a simple discrete time rectangular integrator with Z transform H(z) = 1/(1-Z^(-1)) Plotting the frequency response with Matlab using ...
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### Is real-time Hilbert envelope feasible?

Is the Hilbert envelope (analytic signal) feasible to be calculated in audio frames/blocks in real-time, when using FFT with windowing. What I'm specifically concerned with is that how does it not ...
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### If accept Incoming call which kind of acknowledgement go to the server.? [on hold]

In mobile communication, If accept Incoming call which kind of acknowledgement go to the server.? can i change the acknowledgement..?
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### simulating noise with Yuler and burg

I want to simulate short term white noise with Yuler and Burg. It's said that it can give better results than Gauss-Markov. The problem is that each time the series diverge. Do you think that I made ...
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### Defining an average in time for a density in time

I'm reading the text book "Time-Frequency Analysis" by Leon Cohen and I've made my way through a decent portion. There is however a conceptual issue I keep coming back to. The book states: If we ...
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### Noise reduction on wave file

I have created a simple plot of waveforms using matplotlib of 2 wave files on python. Here is the code: ...
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### probability distribution of complex Gaussian column vector and conditional probability of complex Gaussian column vector

I have column vector $\vec r=[r_1\ r_2]^T$. $$\vec r =hA\vec s +\vec n$$ where $h$ is a complex number , \$\vec n \sim \mathcal{C} \mathcal{N}(\begin{bmatrix} 0 \\ 0 ...
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