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

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Reduce “flicker” in spectrum analysis / spectrogram

I'm performing a series of FFTs on windowed extracts of an input signal, to get a frequency spectrum over time. This is for a visualisation - I'd like to keep the window small, so the visualisation ...
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107 views

Extracting accurate phase and amplitude information from FFT with an arbitrary number of samples

This is a followup question to one I asked earlier based on the chat after the answer given by @hotpaw2, and cross-posted from stackoverflow since it was suggested it is more relevant to DSP. I have a ...
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28 views

extending windowing function to higher dimensions

I was looking at this particular thread that discusses extending windowing functions for singling function to higher dimension. There is one bit in the accepted answer that I could not get my head ...
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49 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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24 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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1answer
40 views

Shape of Kaiser windowing function FFT response

I'm trying to determine the shape of the FFT response of a signal which had a kaiser windowing function applied to it. What I mean by this is if the shape is a normal bell curve or a Lorentzian ...
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1answer
82 views

Measure scalloping loss of window function

Is there an easy/general way to calculate this? For instance, the rectangular window has a maximum scalloping loss of 0.3634, which can be derived in frequency domain from a normalized ...
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82 views

DFT normalization for amplitude estimation

After an interesting recent answer, I'm doing some research on proper DFT normalization for sinusoidal peak estimation. It's clear that to get the correct amplitude from DFT peaks we need to normalize ...
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16 views

Applying window function to Gaussian Like distribution

I am trying to calculate the Modulation Transfer Function (MTF) for a CT scan. I get use the differential of multiple line profiles (as recommended by International Electro technical Commission ...
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22 views

What is the range for alpha in window equations

Alpha is used in many window functions e.g. What is the range that alpha can take and is it the same across all uses of alpha in the equations? e.g. Will any alpha still result in a stable ...
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28 views

Window functions and indexes larger than N/2

How does the n index for a window with $0 \le |n| \le N/2$ e.g the Bohman window function, get implemented when having a specific window size? ...
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1answer
41 views

Fixing for windowing function in FFT

I've been learning about the FFT and about the usefulness of windowing functions. A problem I'm running into is the affect of windowing functions on the amplitude of signals in the FFT. For example, ...
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54 views

Windowing function squared?

Reading this paper about WSOLA (Verhelst, Roelands) At page 2 there's a "time-warped STFT's synthesis function" involving $v(n)=w^2(n)$ which is a windowing function. A windowing function squared. ...
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60 views

Running window maximum: Any cautions?

Are there any statistical concerns with using a running-window maximum to capture peak values? Background: We are measuring acceleration during random impacts on a structure. The impacts need ~500Hz ...
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1answer
69 views

Minimizing sinc spectral lobes

for some reasons I'd like to minimize the secondary lobes of the FFT transform of a rectangular signal (shwon in the upper-left side of picture below) so I've used window function to do that ...
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1answer
469 views

python scipy fft on numpy hanning window smears peaks

I have a signal that I have acquired from an experimental instrument, that I wish to examine in the frequency domain. I don't care about phase for this exercise, I only care about magnitude. I ...
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1answer
67 views

Applying a window to input signal

I am sorry if I say any thing silly .Please forgive me.I want to apply a window to input signals.I have two signals each of which contains zeros (462 samples) and non zeros data (38 samples).I want my ...
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58 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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52 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 ...
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137 views

Fourier transform artifacts

My starting point in what follows is a radially symmetric random field. Taking the Fourier transform of this (and plotting it in logarithm to highlight the patterns), I obtain the following image in ...
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1answer
74 views

Non-separable, higher-order generalized cosine windows in 2D for images

Higher-order generalized cosine windows define a useful parametric family of windows functions, embedding Hamming, Hann, Blackman, Nutall, etc.: $$w(n) = \sum_{k = 0}^{K} a_k\; \cos\left( \frac{2 \pi ...
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1answer
79 views

How is the ends of a bandpass filtered signal reliable after applying the cosine taper?

A taper function decaying to zero at ends such as a cosine window is routinely applied to the signal before bandpass filtering to reduce end effects. Obviously the window alters the waveform. So, as ...
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1answer
62 views

is any filter whose impulse response has a discontinuity in the first derivative fundamentally high-pass?

a triangular (bartlett) window has a kink (discontinuity in first derivative). thinking in the continuous (not discrete) case, my intuition is that the fourier transform of any window with a kink ...
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55 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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1answer
132 views

PSD scaling due to the windowing

I am struggling with the following problem for a while: If I have signal of duration N and I apply window (assume rectangular window) of size M < N how will this influence PSD of that signal after ...
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1answer
81 views

Hamming window for filtering unwanted terms

I am trying to filter off two unwanted terms in this frequency spectrum (the spectrum on top). First, I used a convolution between a rectangular window to make the unwanted terms equal to zero. ...
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93 views

Apply the Hamming window to a sinusoidal signal

I am a novice in signal processing. I am writing a code to apply the hamming window to a sinusoidal signal. So first I have digitized my sinusoidal signal by choosing a sampling rate more than twice ...
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44 views

Formula to get the sui length of Blackman Harris Window

I was reading that I can to obtain the (N) length of Window function. if I have defined: ...
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1answer
101 views

How to Combine FFT Overlap Results?

We currently have C/C++ FFT code with Hann Window function support. For a large data (over 10,000) we want to split this into 1024 samples with 50% overlap. For each 1024 sample, we window and fft. ...
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71 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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2answers
180 views

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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116 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 ...
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1answer
277 views

How to calculate resolution of DFT with Hamming/Hann window?

The frequency resolution of a DFT with a rectangular window of size $N$ is given by $f_s/N$. However, when using other window functions like a Hamming or Hanning window the resolution gets worse. How ...
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92 views

Reconstruction of a windowed signal (specifically Hamming windowed)

Wondering about the resconstruction of the input signal when an overlapped windowing function has been applied. I'm specifically applying a Hamming window with 50% overlap and I wish to reconstruct ...
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34 views

Sensitiviy and Resolution in Windowing Functions

When I read the article Windowing Functions, there are two terms that are does not understanding them well, sensitiviy and resolution. I looked for this two terms on the web, And I conclude that ...
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61 views

Discontinuity at the edge of Chebychev window

I am using Chebychev window for its narrow main lobe. The problem of chebychev window is that it has discontinuities at the edge, and it seems that Taylor window solves this issue. More detail: ...
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1answer
116 views

What windowed Sinc might be closest to a Parks–McClellan low-pass filter?

In another question on dsp.stackexchange, a statement was made that the output of MATLAB firpm() or firls() for an anti-alias low-pass filter was "close" to the coefficients of a windowed-Sinc ...
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24 views

Dolph-Chebychev window and Beam Steering

We have made a Doppler sonar which is comprised of a braodband transmitter and an 8-element receiver arranged linearly. We collected some data at 500 kHz. I would like to steer the beams and apply a ...
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1answer
236 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
61 views

What is the cause of slow roll off of windowed filters

Exactly why using the of windowing function, such as Hamming or Blackman, causes a slower transition to stop band? Everywhere it is mentioned just as an obvious fact that this happens but I haven't ...
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50 views

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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1answer
48 views

Subsampling data: terminology

I'm writing software and the data reporting frequency is slower than the acquisition cycle, so effectively sub-sampling is being done. Different data types require different methods of sub-sampling ...
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97 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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2answers
324 views

Computing main lobe width of Hamming window in Matlab by plotting

I wanted to verify the fact that main lobe width of a Hann/Hamming window is twice that of a rectangular window, using Matlab. I computed the analytical expressions for the respective frequency ...
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1answer
134 views

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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1answer
973 views

How should I select window size and overlap?

I'm new to DSP and I have a wav file with a number of different frequencies playing at different volumes. I'd like to plot the power of the 350Hz frequency signal at each point in time. The source is ...
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27 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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1answer
45 views

Window function for signal with 3-5 sine waves inside

Should I apply some window before FFT if i want to find 5 frequencies in signal? Signal is pure 5 sinusoids + some noise generated during trecording on analog cable.
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199 views

What is the relation of the transition band's width and the filter order for the FIR windowing method

When designing an FIR filter using the windowing method, how can one estimate the filter order ? It's obvious that the type of window and the transitions band's width has some effect on the order.
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Why are there so many windowing functions?

Many windowing functions are listed here in the Mathematica documentation. I tried using a few to reduce leakage when computing a Discrete Fourier Transform. From what I could tell it made little ...