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Questions tagged [window-functions]

In signal processing, a window function is a mathematical function that is zero-valued outside of some chosen interval.

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Increasing the number of points in the frequency spectrum

I have an image with few pixels in length and height. For this image I calculated the two dimensional Fourier transformation. What I got for the frequency spectrum in one direction was a very ...
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131 views

What happens if you apply window after filtering a discrete signal to get it back to its original length?

What happens if you filter a discrete bandpass signal of length $N$ with a bandpass filter(Hann truncated sinc) of length $L$ and apply a window of length $N$ to the filtered signal of length $N+L-1$ ...
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MATLAB : How to filter a data signal

I have a data signal (column vector) with N values taken over at specific sample rate (dx) at a fixed frequency. After taking the Fourrier transform of this signal and representing it in the Fourier ...
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751 views

segmenting an EEG data

I have an EEG labeled data, which is the data that used for training, And I want to segment those data based on the time of EEG signal (Time-based Epoching) as a preprocessing step, based on the ...
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162 views

Overlapping power-of-cosine windows with constant weight

I would like to refer you to a relevant question I posed on the Math StackExchange: A generalisation of the Pythagorean trigonometric identity. As can be seen from the question and the answer, what ...
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273 views

When does a Window function's sidelobe level become out of band attenuation?

Another question I'm struggling to answer by myself. For a Window function, say Blackman (response pictured), what is the out of band attenuation? If I'm designing a filter with out of band ...
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1k views

How to calculate the power of a discrete signal? / Clarification on PSD estimates

I want to calculate the channel power $ P_\mathrm{x}$ of a given discrete and complex signal $x[n]$ (with a length of N) in a given bandwidth $B$. I'm aware, that I could probably apply a sharp ...
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385 views

Filter, window function and audio signal: how to link them to each other?

I have a question about the implementation of digital filters in CoreAudio. I'm in big trouble because it is a few weeks I'm trying to understand how to implement them. The basic idea is this: while I ...
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1answer
64 views

Difference between applying a window to a whole signal and frames.

I'm going to do feature extraction using a speech signal. The first step is the windowing of the signal using Hamming window. I'd like to know if I should apply one single window to the whole ...
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1answer
956 views

Power Spectrum in dBFs

I'm trying to get the spectrum of my signal in dBFS units. I'm not sure what is the refernce that I should devide by. I computed the power spectrum as follows: 1) FFT normalized to the number of ...
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1answer
80 views

Should I use window or any filtering to average my data?

I have 80 seconds of data and I have to score my data by taking the average or median (or some other method) every 10 seconds. What's the best way to do this ? Should I just use a regular rectangular ...
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162 views

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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175 views

Auto correlation properties of window functions in pulse compression application

It is known that different window functions perform differently and users pick a window function (in amplitude modulation) based on their application or requirement. I am trying to pick a window ...
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0answers
367 views

DFT sinusoid's fundamental frequency, intuitively

I am trying to understand, intuitively, the mapping of a sinusoidal signal's fundamental frequency from time domain to frequency domain using $\textrm{DFT}$ formula. Given the time domain samples $\{x[...
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0answers
864 views

Matlab: Estimating power spectral density of an experimental data?

How do I estimate PSD in matlab ? There are lots of methods to estimate, depending on application. I am using an experimental data to identify faults ( e.g. interturn fault of electric motor), which ...
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How exactly does one apply a Hanning Window for a spectral estimate?

PREAMBLE I am a graduate student researching evolutionary ecology. My supervisor and I have been trying to learn how to simulate colored noise, discretely, by the $\frac{1}{f^\alpha}$ power law for $\...
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42 views

Frequency bins too powerful at the start and at the end of each sample computed DFT data

I've taken the following link http://coding-geek.com/how-shazam-works/#comments as a project to start practising and learning signal processing and python programming for me to get started in speech ...
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206 views

What is the algorithmic latency of STFT processing?

I was reading this paper, and in section 3 I got a bit confused. It claims that the algorithmic latency is equal to synthesis frame length. If the overlap between two consecutive frames is 50%, the ...
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35 views

Multitapering in time domain to obtain smoother filtered signals?

Suppose we want to approximate the instantaneous power $z(n) = |y(n)|^2$ of the discrete-time signal $y(n)$, where $y(n)$ is the result of filtering $x(n)$ with a given window $h(n)$, $y(n) = x(n) \...
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FIR filter design in matlab using Kaiser window (using 'fir1' and 'designfilt')

Here are the specs for FIR filter using Kaiser window. ...
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Where can I find more information about this formula relating a window's time and frequency size?

I remember having seen a formula of the form $C=\frac{B}{L}$ that relates a duration $L$(s) of a window to its width $C$(Hz) in the spectrum (defined at -3dB or so). The constant $B$ would be ...
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86 views

Window function on large arays

Hello I'm reading the following document to better understand windowing and how to use it. "Spectrum and spectral density estimation by the Discrete Fourier transform (DFT), including a ...
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61 views

Specifications (N) FIR Low Pass Resamplig, Hamming Window

I'm learning about DSP and I've doubts. The resampling process can be do it with only one filter. $L$: Increment Sample Rate Integer $M$: Decrement Sample Rate Integer $f_S$: Frequency Sampling ...
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instantaneous frequency

If my signal is $$ f(t)=\exp[i\phi(t)], $$ how do I show that $$ \int_{-\infty}^{\infty} {\xi}\left|S_f(u,\xi)\right|^2 d\xi = 2\pi\int_{-\infty}^{\infty} {\phi'(t)}\left|g(t-u)\right|^2 dt, $$ ...
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How to relate power spectral density with the number of resource blocks in LTE?

I am running a simulation with 100 Resource blocks for LTE OFDM and I plotted a PSD for it. Now I am able to bring down the out of band emissions when I perform an algorithm on it. Based on the ...
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35 views

Attempting to remove the 60Hz frequency out of a noisy ECG signal

load eeg_plus_noise Fs=200; Fn=Fs/2; b = fir1(64,[59.8 60.2]/Fn,'stop'); figure(3) freqz(b,1,512,Fs); y = filter(b,1,eeg_plus_noise); I am then using the ...
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Windowing in frequency domain. how to cut a spectrum using window function in frequency domain?

I have a set of measurement data of a FMCW radar and trying to estimate the system transfer function. In the frequency spectrum, I can see multiple peaks due to the non-linearity that exist in the ...
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How to extract desired frequencies from a spectrum using e.g. a Parzen window?

Disclaimer: I am a geophysicist working with time-domain data which needs to be converted to the frequency domain evaluated at a specific set of logarithmically-spaced frequencies. The textbooks I am ...
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200 views

Edge effects in cross-correlation

This is a follow-up of this question. The problem explained in the linked question has been in part solved by the mean of a windowing function. But my cross-corrleation still exhibits strong edge-...
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156 views

Analysis with Window before FFT

I have two signals $x$ (see below) and $k$ (obtained by giving circular shift of 106.5849 in $x$). Before I take FFT of both ($x$ and $k$) I want to do window analysis on them. Kindly can some one ...
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123 views

Lost power while using FFT with apodizing mask

Previously I asked this question about FFT artifacts. The solution that is most easily implemented is using an apodizing mask on the original image, tapering the borders to zero making the image left-...
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277 views

hamming window for LPC

I am working on a library for generating LPC for speech synthesis. I am currently using a hamming window for the spectral analysis which goes in 200ms blocks over the signal, and does the a-to-k ...
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Audio output distorted with any FFT Windowing other than rectangular

For an experiment i have a simple application that takes a quadrature signal from a radio and then does the following: Complex FFT -> Inverse FFT -> Cartesian to Polar -> audio out If I tune the radio ...
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55 views

Relation between Gaussian and Savitsky-Golay kernels

I would like to make a mathematical comparison between two methods in my field. One smooths with a Gaussian filter, and one smooths using a second-order Savitsky-Golay filter. Let's say the window ...
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213 views

BandPass and StopBand FIR filters (Hamming) is not working

I have two groups of 3 frequencies of tone (music), First Group Tones: 39 (77.7817 Hz), 40 (82.4069 Hz) and 41 (87.3070 Hz). Second Group ...
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268 views

Reducing latency due to FFT windowing for a real-time signal

I need to compute the amplitude of a certain frequency band as the input to a PID algorithm. My system looks like this: ...