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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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Which FFT Window to use for data gathering of complete mastered songs - for AI

I have a novel technology that I developed, which I plan on incorporating AI beginning with simply recording a basic machine learning strategy of Input - Output for eventual training. In this case ...
Sarp Saysel's user avatar
4 votes
1 answer
66 views

How does MATLAB's edgetaper function work?

MATLAB has a function edgetaper that does something I haven't seen before: J = edgetaper(I,PSF) blurs the edges of the input ...
Cris Luengo's user avatar
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Differences in PSD for windowed vs non-windowed spectra

For a non-windowed spectrum, this article gives this equation for the power spectrum $$\text{PS}(k)=\frac{1}{N^2}|X(k)|^2$$ and this for the power spectrum density $$\text{PSD}(k)=\frac{N}{f_s}\text{...
RF Shenanigans's user avatar
10 votes
3 answers
1k views

Why doesnt DFT Padding cause sinc like features

I'm new to the land of DSP so any incorrect terms please let me know. It seems padding the time domain signal can make the magnitude spectrum look 'nicer', the fact it doesn't gain any more useful ...
George kirby's user avatar
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How to find frequency , location and phase of two sinusoid signal buried in noise?

There is a data set which has two different sinusoids buried in noise. Data record has following properties: A data records with a total data length of 2048 points. The sampling frequency is 100 Hz. ...
Thouhidul Islam's user avatar
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Looking for an online course

I work for a company with expertise in electromagnetics physics, specifically dealing with time domain-based simulation software. We routinely need to transform our results into frequency domain, ...
DrEarlGray's user avatar
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1 answer
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Calculating stopband cut-off frequency and stopband attenuation for FIR lowpass window filter

I am aiming to create a digital windowing FIR filter on MATLAB and have been given specs such as a: sampling frequency of 360Hz maximum filter order of 5 cut-off frequency of 98Hz/ 1.710rad/sample (...
EEE22's user avatar
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Filter coefficients hamming window for low-complexity Welch PSD computation

I am trying to implement the proposed method from this paper 1, to eventually have a more efficient PSD computation for feature extraction on a microcontroller. The method is suitable since I am using ...
michael's user avatar
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Speech Endpoints Detection using Explicit approach

The "Fundamentals of Speech Recognition" text by Rabiner, mentions three approaches for Speech (Endpoints) detection - Explicit, Implicit, and Hybrid approaches. I am studying the block ...
Anantha Krishnan's user avatar
3 votes
1 answer
180 views

Why is there a tradeoff between simplicity of a window function and its ability to be adjustable and controllable?

While studying and applying different window functions in a project I am working on, I found that known windows (here is an example paper which cataloged numerous windows) suffer from 2 kinds of trade-...
RajaKrishnappa's user avatar
2 votes
1 answer
140 views

Window function with no sidelobes

I found the Hann–Poisson window on Wikipedia. It has no sidelobe for $\alpha \ge 2$. I am interested to know more examples of such window function with no sidelobes and what they are useful for. I ...
anonymousRabbit's user avatar
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What are the *undesirable* effects of windowing in Fourier space?

My goal is to split a periodic signal into two (or more) signals. The first signal would contain the low-frequency information, and the later signals, the higher-frequency information. These signals ...
user572780's user avatar
2 votes
1 answer
363 views

Taylor Window Algorithm

I am trying to find out the algorithm for taylor window function but i have looked everywhere and i dont see any proper algorithm. I read it is similar to Kaiser Window but thats all I know. Can ...
Shubham Kapoor's user avatar
3 votes
1 answer
91 views

Why window functions can't have both narrow main lobe and low-level side lobes?

Why window functions can't have both narrow main lobe and low-level side lobes? i got a hint from my mentor that it's quite often expained in books about wavelets... I thought it could be associated ...
Alexander's user avatar
1 vote
2 answers
141 views

What can be done, on top of windowing, that can reduce spectral leakage?

I am relatively new to DSP, and I am trying to create a spectral suite plugin using the IPlug2 library for creating vst plugins, and an FFT library I found on GitHub. So far, I can perform an FFT on a ...
Kallyn's user avatar
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Welch method implementation not smooth

I have been trying to recreate the welch method implemented in scipy.signal by hand but my results don't look close enough in my opinion. How come the scipy.signal.welch method is displaying much ...
Flitschi's user avatar
1 vote
1 answer
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Calculating the main lobe width of Dirichlet kernel

The Dirichlet kernel of order $N$ is defined as: $$ D(\theta,N)=\frac{\sin(N\theta /2)}{\sin(\theta /2)} $$ We know that the main lobe widths between zero crossings is: $4\pi/N$ I was wondering if ...
Sammy Apsel's user avatar
2 votes
1 answer
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FFT Window question - high resolution windows

So I am pretty familiar with FFTs and FFT windows. I know that in general there is a tradeoff between mainlobe width and sidelobe levels. However, I recently stumbled across this discussion, where ...
Colin Marcus's user avatar
7 votes
1 answer
143 views

What window functions allow for controlling the location of nulls?

Window functions are commonly used to control spectral sidelobes. Typically there is a trade between supressing sidelobes, and maintaining the resolution of the mainlobe. A window with lower sidelobes ...
Gillespie's user avatar
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177 views

Decreasing gibbs phenomenon with window functions multiplied in time domain

I know about using fitering(e.g. window filters that used in frequency domain), wavelets for decreasing or even full eliminating gibbs effect but don't really understand how we can use window ...
Alexander's user avatar
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How to adjust the length of the window of the Fourier transform with respect to the length of the signal in Python

I ran the following code in Python, setting the window length to 5s, but he reports an error as the window length does not match the signal length. How should I adjust it please? code: ...
BaiYueChu's user avatar
2 votes
1 answer
113 views

Noise spectral density and windowing

I am wondering about the definition of Power Spectral Density, in the context of measuring noise, i.e., Johnson-Nyquist (thermal) noise. Usually a windowing method, like Welch's method, is used to ...
Nick's user avatar
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Power spectrum, Power spectrum density and windowing functions

At the moment I have some trouble understanding the different methods. I would like to calculate both the Power Spectrum and the Power Spectrum Density. As the name suggests I thought that $PSD = PS / ...
3dSpatialUser's user avatar
3 votes
1 answer
222 views

How Best to Characterise a Window Function

How do I characterise my window function? Do please forgive me here as I am more a practical than theoretical person. I have invented a window function which I use prior to discrete Fourier transforms....
Richard's user avatar
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108 views

Dropping the zeros at the edge of window functions

I have learned that Scipy's implementation of the Hann window allows receiving both a symmetric window, and a periodic window (meaning the last zero element is dropped). As far as I understand, the ...
Gideon Genadi Kogan's user avatar
1 vote
1 answer
210 views

N-point DFT of window function

I am currently choosing a window function to analyze signals in frequency domain. While I understand the reasoning behind using a window function and what to look for concerning main lobe and side ...
Geralt von Riva's user avatar
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25 views

Kaiser window but desired frequency response extends beyond pi?

Passband : 0 to 0.5π Stopband : 0.7π to 2π Is there a way to reduce this to a 0 to π scale? If I had to guess, we should be able to simply divide the edge frequencies by 2 and use the time scaling ...
rjpj1998's user avatar
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1 answer
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Understanding FIR windows

We learnt about the various windowing techniques recently and I can't seem to wrap my head around why one would use anything other than a rectangular window. I created a signal with 10 evenly spaced ...
rjpj1998's user avatar
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2 votes
2 answers
707 views

Amplitude scaling of window functions for FFT

I need to perform an FFT on a signal sampled with 20 kHz and a measurement time of about 10 seconds. The signal contains frequencies of up to 2 kHz but I am mainly interested in the bandwidth of 0 to ...
Geralt von Riva's user avatar
1 vote
1 answer
110 views

Effect of windowing on signals

I have an input signal of frequency 1000Hz. Sampling frequency=16kHz. I compute the FFT on 128 input samples and plot the magnitude spectrum. I am not doing the normalization by 128. My two sided ...
Aami's user avatar
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Proof for the energy correction factor of DFT

I am looking for a mathematical proof for the energy correction factor in conteext of windowed discrete fourier transform. In Spectrum and spectral density estimation by the Discrete Fourier transform ...
mocquin's user avatar
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How to understand "independent sample rate" of windows?

A window metric called independent sample rate is given in a book that I recently read. It says that in spectral estimation, the variance of power-level estimates is inversely proportional to the ...
ecook's user avatar
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1 vote
1 answer
133 views

What is the necessity of shifting the impulse response of a filter to the front of the time domain buffer and windowing?

I was reading the answer to this question provided by Phil Karn. In the answer, it has been said: Ensure that the impulse response of your lowpass filter is shifted to the front of your time domain ...
alireza's user avatar
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Trade offs in window based design of FIR filter

Please find attached snap of proakis dsp book. It shows rectangular window has minimum value of stop band attenunation and transition width and as we go on towards Hamming and Blackman window,stop ...
DSP_CS's user avatar
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4 votes
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How does the effect of windowing change with the phase of the input signal?

I am calculating the SNR (signal power to noise power) for a sine wave. I don't have an integer number of periods in the waveform being analyzed, so I am using a flattop window to reduce spectral ...
DavidG25's user avatar
  • 119
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1 answer
567 views

Applying Hanning window $w_n=1-\cos\Big(\frac{2\pi n}{N}\Big)$ to data

I have a time-series data file in python and I am asked to apply a Hanning window $w_n=1-\cos\Big(\frac{2\pi n}{N}\Big), 0\leq n\leq N=\text{file length}$ to the data given. I am very new to this ...
LianNuo 's user avatar
2 votes
2 answers
194 views

FFT of 2 sine tones using windowing and zero padding. Wrong FFT amplitude

Here is my attempt to perform an FFT on a random signal with 2 tones in which I applied zero padding AFTER windowing. (I did not apply zero padding before windowing because that would suggest that the ...
shoggananna's user avatar
2 votes
1 answer
132 views

Correct Windowing Effect at Amplitude Scale

I am trying verify the noise floor returned by Matlab sinad(). I am able to get the results matching by summing power spectrum density with $\frac{f_\text{s}}{N}$. ...
John L's user avatar
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0 answers
52 views

Determining minimum window length for DTFT [duplicate]

Let $x(t) = \cos(2\pi\times15t)+\cos(2\pi\times22t)+\cos(2\pi\times35t)+\cos(2\pi\times42t)$ and $\forall t\in\mathbb{R} :w(t) = 1$. We sample $x(t)$ and $w(t)$ with $F_s = 92 \ \text{Hz}$. So we ...
S.H.W's user avatar
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What is the right scaling factor to get the amplitude after aplying a hanning window? [duplicate]

I have a waveform where I sliced the flat top so I can do some analysis on the amplitudes of each frequency. I have a dataset of N measurements each with M samples of current (A) over time (...
Typhaon's user avatar
  • 111
4 votes
1 answer
185 views

Are there windows that create asymmetric sidelobes

I am working on a project which uses radar imaging. The radar imaging takes place at a relatively small distance from the radar (0.25m to 3m). The data is collected using an FMCW radar. The FFT of the ...
CMH12's user avatar
  • 89
1 vote
2 answers
812 views

Converting a triangle from the frequency domain to the time domain

I’ve been given a triangular signal that looks like this: $$ X^{F}(\omega) = (2 -|\omega|) \cdot W_{[-2,2]}(\omega)$$ (this is just my interpretation of the signal from a picture I’ll add). I was ...
Piratemetaldrinkingcrew's user avatar
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1 answer
60 views

Is Hann-windowing applicable when calculating a DTFT?

I have read that people often use a zero-padded DFT with Hann-windowing to get the amplitude+phase information at one frequency (where the Hann window is used to reduce the effect of a small/finite ...
Chillpadde's user avatar
1 vote
1 answer
1k views

What is the energy`correction or amplitude correction for a Tukey window?

From this page: https://community.sw.siemens.com/s/article/window-correction-factors there is a list of correction factors for popular windows. Is there a correction factor for Tukey window, depending ...
birki's user avatar
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0 votes
2 answers
242 views

How does applying a unity-gain Hann window to White Noise change its power?

What works: I generate real-valued white gaussian noise with standard deviation $\sigma$ I calculate the FFT of this noise. The Abs of the FFT is a flat noisy trace over frequency, as expected for ...
tobalt's user avatar
  • 468
1 vote
1 answer
543 views

Window gain factor and amplitudes in FFT

I have some vibration data (acceleration) on which I need to perform an FFT, integrate it and again do an FFT. I read that for the nature of the data that I have, the input to the FFT must be first ...
Teja Jupudi's user avatar
2 votes
1 answer
376 views

Applying Kaiser Window to sinc interpolation

I am trying to apply the kaiser window during sinc interpolation. The following is my sinc interpolation code: ...
Hari's user avatar
  • 93
1 vote
1 answer
54 views

Overlap correlation indices in Harris 1978

In the heavily cited paper by Harris 1978, there is a section on "Overlap Correlation" where he's using a "fractional overlap r" in his equation. Here is a screen shot from the ...
ThatsRightJack's user avatar
2 votes
1 answer
112 views

Window Choice of FFT

I am working with data from a TeraFlash THz Spectrometer from Toptica, which gives me the pulse in the time domain and the spectrum in the frequency domain I have been experimenting with the FFT to ...
lazerlini's user avatar
0 votes
3 answers
1k views

Number of periods of signal required when doing an FFT

I'm using numpy.fft in python to compute Fast Fourier Transforms. In particular, I'm using rfft as I have a real signal and don'...
Bern's user avatar
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