Questions tagged [window]

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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
1 vote
0 answers
71 views

STFT normalization

In Scipy's implementation of STFT, an argument allows to scale the result as a spectrum or as a psd : ...
hugopb82's user avatar
7 votes
1 answer
139 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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0 answers
59 views

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
1 vote
1 answer
80 views

Can I apply an hilbert transform on a signal in subsegments [windowed hilbert transform?] [duplicate]

Consider I have a signal x which has N samples, N being a very large number. Could I create y, the analytical signal of x, by ...
Mart's user avatar
  • 195
1 vote
1 answer
79 views

Multiplying a finite signal with a unity window

I have a simple question to ask: Suppose $x[n]$ is finite and has a support for $|n|<L$ Let's denote its DTFT by $\operatorname{DTFT}\big\{x[n]\big\}(e^{j\omega})=X(\omega)$ Let's consider a unity ...
Sammy Apsel's user avatar
0 votes
1 answer
241 views

properly windowing for better FFT signal

I have an analog signal as shown below. As you can see it has a DC component, a 1MHz component and some high order component. The period of the signal is 8.0199667µs. I want to see a good accurate ...
lub2354's user avatar
  • 113
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0 answers
62 views

How best analyze a very short data record (~100 data points) windowing and padding data to perform CWT

I have short segments of a biological signal interpolated at 10 Hz (anywhre from about 8.5 sec to 10 sec length). I want to use a cwt to then convert this segment to frequency over the short time ...
Ken's user avatar
  • 1
2 votes
1 answer
187 views

upward shift in FFT windowed - attenuate fluctuation in FFT

I would like to limit the noise after the FFT. I have used this strategy: Divide the signal in segments using a Hann window Perform abs(FFT(segment)) Ensemble ...
user49811's user avatar
0 votes
1 answer
36 views

Inverting the normalized Gaussian to get a kernel window radius

I am seeking to compute a kernel radius to use with my gaussian convolution filter, and inspired by https://stackoverflow.com/a/68050503/, I came up with: $$r=\sqrt{-2\sigma^2\ln\left( \epsilon\sigma\...
multiscale's user avatar
0 votes
2 answers
2k views

FFT of signal data with windowing, overlapping and averaging

This is my first ever question here so the help is really appreciated. I am performing FFT on a signal. I want to perform windowing, 50% overlapping and averaging to the signal. There is a function <...
Anique Ahmed Khatri's user avatar
0 votes
1 answer
504 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
8 votes
2 answers
1k views

Proof that the rectangular window has the best resolution

The resolution of a window is typically defined by the width of its spectral mainlobe (3dB-width or null-to-null width). It is often stated that the rectangular window has the best resolution among ...
Lukas's user avatar
  • 185
2 votes
1 answer
292 views

Window with optimal sidelobes for a given ENBW / frequency-resolution

Is there a family of windows which is "optimal" in terms of energy above/below a boundary, but with controllable ENBW/bandwidth? By optimal, I mean maximising energy concentration inside ...
cloudfeet's user avatar
  • 301
1 vote
1 answer
2k views

Do we guess the cut off frequency when passband edge frequency and stop band edge frequency are given? FIR Filter design-LOW PASS FILTER

Say passband edge frequency=0.25 $\pi$ Stopband edge frequency=0.35 $\pi$ What is the cut off frequency? Do we average these 2 frequencies and write the answer or what is the procedure to find cut off ...
abdulkhan's user avatar
2 votes
1 answer
153 views

Biorthogonal Windows

I am starting to study about the concept of biorthogonal windows and the relation to (Discrete) Fourier transform and short-time Fourier transform (STFT). I have not found an introductionary review of ...
Triceratops's user avatar
0 votes
1 answer
188 views

Confusion understanding phase shift/delay?

I am reading proakis, as shown highlighted in attached snap shot,there is '-'sign along with j,but still it is written (underlined red) implies shift in positive n direction,why and how positive?when ...
wer's user avatar
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1 vote
0 answers
19 views

Apply window taper for selected window or to full data block in algebraic problem with known frequencies?

First, I'd like to introduce a problem. I try to solve a set of linear equations in LS (Least Squares) sense, i.e. Ax=y (LS) => A^TA x = A^T y. x is a vector I'm looking for, but y is a measured ...
Adam Ciesielski's user avatar
5 votes
3 answers
547 views

Can I use more than one Window on an FFT?

I was wondering if it is possible to take a signal and run it through an FFT multiple times with a range of different windows, and then combine/average the results to get a more accurate Signal ...
Jacob wood's user avatar
0 votes
2 answers
429 views

Windowing of signal before FFT

I am facing an interesting problem: I have a signal in the time domain. In order to avoid discontinuities at the edges of the signal --- which would lead to artifacts when calculating the FFT --- I ...
Sandro Camenzind's user avatar
0 votes
0 answers
86 views

Blackman window magnitude attenuation

I am trying to compute the fundamental phasor using sliding window DFT. I have employed a Blackman window in conjunction i.e $$ \sum_{k=0}^{L_{DFT}-1}x(k) w(k) e^{-j2\pi k/N} $$ where $x(k)$ is the ...
mka_07's user avatar
  • 15
1 vote
1 answer
159 views

minimal signal window size (length)

In order to detect a frequency component of 1 Hz with a DFT - do I need a signal window (signal in time domain) of at least 1 second length (in order to have at least 1 cycle of the desired minimal ...
Andreas's user avatar
  • 11
0 votes
2 answers
171 views

why is the signal divided into epochs in EEG classification?

I'm new in EEG signal classification. Studying the literature on this topic, I wonder why the EEG signals are divided in epochs, so, instead of classifying the whole signal all at once, we usually ...
volperossa's user avatar
0 votes
1 answer
115 views

Discrete Signal Windowing

How do we apply windowing of 50% (4 samples) to a discrete signal with the odd number of values as 1234567? Is it done as: ...
Konzo's user avatar
  • 1
1 vote
2 answers
4k views

Find the Equivalent Noise Bandwidth

I have already asked (in another thread) how to quantify (specify) the window function I have created. One figure I need it seems is the Equivalent Noise Bandwidth (ENBW) Or Noise Equivalent Bandwidth....
Richard's user avatar
  • 101
0 votes
0 answers
38 views

How to specify a window?

I have developed my own window function for pre-processing signals prior to a DFT (FFT). How do I measure the performance of the window so that I can specify how good (or bad) it is? Maybe other ...
Richard's user avatar
  • 101
1 vote
2 answers
98 views

Frequency Support of Window Functions

All window functions, which go from zero amplitude, up, then back to zero amplitude, are all base-band signals. Why is this? Are all functions that have this behavior always band-band aka low-pass?
The Dude's user avatar
  • 632
1 vote
1 answer
132 views

Is it okay to interpolate between overlapping areas obtained using a sliding window?

I am using a 50x50 pixel sliding window which moves left to right every pixel so that it covers a whole binary image which is about 2000x2000 pixels. In the window, the ratio value of black to white ...
sgericeb's user avatar
2 votes
1 answer
472 views

Why coherence function calculation needs averaging of different segments of the signal?

I am trying to understand coherence function calculation. I am working with a non-linear system without any noise. Coherence function is defined as: I understand that coherence is 1 for N=1, but I ...
Swati Jain's user avatar
0 votes
1 answer
1k views

RMS from calculation from PSD using Welch's method [duplicate]

I've used Welche's method on a vibration signal to get the averaged FFT which I want to used to calculate the PSD from which I can calculate the RMS. Within the Welche method i've use Hann window ...
G.David's user avatar
1 vote
3 answers
2k views

Rectangular vs Hann windowing

I'm trying to create a basic digital signal processing pipeline, to manipulate a WAV file. Nothing fancy, I'm just looking to apply some filtering. My first attempt was to divide the input signal to ...
WantsToLearn's user avatar
0 votes
1 answer
574 views

Energy using Hanning window

I am a newbie in signal processing. I am testing the Hanning window on a signal. Obviously doing this window also means cut some energy of the signal, and when I do the DFT, the 0 frequency is not ...
Luca Mirtanini's user avatar
3 votes
1 answer
2k views

Use of Tukey window and its effect on a graph

I am trying to minimize the noise in a spectrum of a variable. I am trying to to divide the time history in equal parts, to do the FFT of this time history parts and to do an average between these FFT....
Ashish Bhigah's user avatar
0 votes
1 answer
316 views

When can a windowed cosine be considered band-limited signal?

I have an exam in the following days and i have no clue of what is the response to this question in the exam: given this signal: $$g(t) = H\left(t+\frac{T}{3}\right) f(t) - H\left(t-\frac{2T}{...
Dario Formi's user avatar
0 votes
1 answer
132 views

Peak to Average Power Ratio of an exponentially increasing signal

I am having an exponentially increasing sinusoidal signal. After sampling, I am dividing the signal into frames of length 128 and doing windowing operation with a hanning window of length 128. Then ...
Deepa's user avatar
  • 315
-1 votes
1 answer
165 views

DTFT of window function applied to input signal

$$x[n] = \cos(\omega_1n) + \cos(\omega_2n)$$ $w[n] = 1/N$ for $0 \leq n < N, 0$ for everything else Find the DTFT of $y[n]=x[n]w[n]$ expressed by the DTFT of $w[n]$, $W(\omega)$ I was thinking ...
Matty111's user avatar
1 vote
2 answers
806 views

Multi Resolution STFT for audio

I am looking at trying to achieve a multi resolution STFT analysis on a log sine sweep audio measurement. I have an impulse, and I would like to perform two different windowed length FFTs on the ...
samp17's user avatar
  • 159
0 votes
1 answer
149 views

Yet another fft question - a vocoder

Lets assume a pipeline X: ...
Michal Pawluk's user avatar
1 vote
2 answers
831 views

Half Window Functions and Formulas

I am looking at implementing different window functions in an application I am making. I have found the formulas for all major symmetrical windows, however I would like to implement half windows. ...
samp17's user avatar
  • 159
2 votes
2 answers
225 views

What is the proper way to filter out unwanted noise from accelerometers?

I'm a beginner in signal processing and have a hard time to filter out environmental noise from the floor vibration data collected using accelerometers. I have tried using butterworth filter (IIR) ...
DrakeL's user avatar
  • 21
0 votes
1 answer
353 views

How to deal with overlap in STFT when considering the highest energy among multiple channels

I have a 4 channels audio file. As a pre-processing step, it goes through an STFT with $T$ frames and $M$ frequencies. The output is divided into magnitude and phase per channel, so for $C$ channels, ...
havakok's user avatar
  • 672
5 votes
1 answer
10k views

Hanning and Hamming Window

I am new in the field of signal processing. What's the different between Hamming and Hanning window? When we use the former and latter?
Andreas Chandra's user avatar
1 vote
0 answers
104 views

Is there a window with both a lower side lobe level and higher side lobe roll of rate than Blackman

Is there a window with both a lower side lobe level and higher side lobe roll of rate than the Blackman window - even if it is poor or useless for some other reason?
Richard's user avatar
  • 101
0 votes
3 answers
344 views

Multiple different length Windows for high resolution realtime FFT

I am looking at trying to achieve a 'realtime' (as quick as possible to acquire, process and present data) FFT application to analyse audio. I have setup my app to acquire a set of samples, apply a ...
samp17's user avatar
  • 159
10 votes
4 answers
11k views

What is Frequency Resolution?

Im trying to tackle the following problem while still not having a firm idea on what "frequency resolution" means : Suppose we sample a continuous time signal with sampling period Ts = 1/2000, and ...
Αποστολης Καρασμανογλου's user avatar
0 votes
0 answers
160 views

How to know the time of my window to calculate the STFT with python knowing only the length?

I am trying to implement a work presented in an IEEE paper where they have mentioned that the STFT was performed on the signal measurements to obtain a spectrogram with no overlap window of 3 min : I ...
MakBad's user avatar
  • 1
0 votes
1 answer
39 views

identify equilibrium region after large transient

I am looking at data from a mechanical system under an unsteady load. I'm trying to find the simplest way to identify the portion of the signal once the system reaches its new equilibrium. Here's a ...
weymouth's user avatar
  • 101
2 votes
2 answers
289 views

Fundamental misunderstanding of windowing

I believe I have a fundamental misunderstanding of windowing. I thought that windowing is applied to a signal with pointwise multiplication, then some sort of filtering is then done to it (say using ...
Xymistic's user avatar
1 vote
2 answers
2k views

How to design a lowpass filter using Hamming window and sinc function

I have these three equations and have a noisy voice signal. I have to design a low pass filter of length N=1000 using hamming window technique. I have selected its cutoff frequecny 0.25 (normalized). \...
M.Digits's user avatar
5 votes
3 answers
4k views

Correct method for processing FFT in realtime

I am attempting to build a 'live' FFT for continuous analysis of an audio signal. I am relatively new to this, but have attempted the full thing, and then updating the graph at 20Hz refresh rate. My ...
Sam Proctor's user avatar