Questions tagged [window]
The window tag has no usage guidance.
100
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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 ...
- 1,632
0
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0
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34
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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 / ...
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1
vote
1
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63
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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 ...
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1
vote
1
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77
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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 ...
- 113
0
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1
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176
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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 ...
- 113
0
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0
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61
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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 ...
- 1
2
votes
1
answer
171
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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 ...
- 33
0
votes
1
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36
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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\...
0
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2
answers
975
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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 <...
0
votes
1
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365
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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 ...
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2
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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 ...
- 175
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1
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218
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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 ...
- 261
1
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1
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1k
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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 ...
- 11
2
votes
1
answer
148
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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 ...
- 398
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1
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124
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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 ...
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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 ...
5
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3
answers
464
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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 ...
- 141
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votes
2
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409
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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 ...
0
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0
answers
83
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 ...
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1
vote
1
answer
136
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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 ...
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2
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153
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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 ...
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109
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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: ...
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2
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3k
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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....
- 101
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35
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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 ...
- 101
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2
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93
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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?
- 632
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122
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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 ...
- 13
2
votes
1
answer
394
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 ...
- 21
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votes
1
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909
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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 ...
- 1
1
vote
3
answers
1k
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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 ...
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0
votes
1
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474
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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 ...
- 422
3
votes
1
answer
1k
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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....
- 155
0
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1
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290
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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}{...
0
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1
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121
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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 ...
- 293
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165
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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 ...
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2
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730
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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 ...
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1
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145
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1
vote
2
answers
760
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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.
...
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2
answers
200
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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) ...
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votes
1
answer
337
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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, ...
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1
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9k
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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?
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0
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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?
- 101
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3
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332
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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 ...
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4
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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 ...
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0
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158
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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 ...
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1
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38
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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 ...
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2
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257
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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 ...
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2
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2k
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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).
\...
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3
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4k
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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 ...
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676
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Interpolated FIR filter group delay
I'm trying to design a digital low pass filter with a narrow transition band. My sampling rate is 25 kHz, the cut off frequency is 60 Hz & the transition band width is 4 Hz. I'm looking for about ...
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0
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383
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Windowing a signal by using Hanning / Hamming or... zero padding?
My question is about the use of Hanning or Hamming windows versus "square" windows.
In my understanding, I will use a Hanning or Hamming window to limit the spectral leakage. But, on the second hand, ...
- 151