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

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How to compute the main lobe width of generalized Hamming windows (i.e. Hann, Hamming, etc.)?

Is there a way to compute the main lobe width of windows of the generalized Hamming window family (i.e. Hann, Hamming, etc.)? By main lobe I mean the first zeros left and right of the center of the ...
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100 views

At which point in the signal processing chain to use Hann Window?

I have a question about signal processing. Experienced with embedded design and code, but DSP is in new territory. Thus far I am using the CMSIS DSP library functions, which are working well. I am ...
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51 views

Improve spectrogram appearance using windowing functions MATLAB

I have a program which plots data obtained in a NI USB DAQ realtime to a spectrogram plot using the surf function. I'd like to improve the appearance of the plot using some sort of windowing function. ...
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81 views

How can I load a wav file, split it in frames, apply different filters do different frames and then recombine the filtered frames into a single file?

I'm working on a wav audio file using MATLAB. What i would like to do is: load a wav file and divide it into frames of the same dimension filter these frames (with a different filter for each ...
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88 views

Window functions with rippleless spectra

On Wikipedia I found the Hann-Poisson window, and the article claims the spectrum is smooth, but it isn't theoretically smooth, as it turns out. In practice you achieve partial smoothness by jacking ...
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89 views

What exactly is the effect of a Hann Window on the FFT output?

In the code I am trying to understand, there is an usage of Hann window multiple times (There's overlapping frames, the size of each is 512 and the overlapping factor is 75% so each time we capture ...
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88 views

A question about spectral leakage

I have read about spectral leakages in other posts here. From what i understand, it occurs because you dont have an integer number of time periods in your sampled data. By default a rectangular window ...
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59 views

Spectral leakage - understanding the integer number of cycles while windowing

I am reading tutorials about windowing and have read following sentence: For an integer number of cycles, all smoothing windows yield the same peak amplitude reading and have excellent amplitude ...
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61 views

is there a mathematical relation between percent overlap and window length or amplitude

I am trying to plot short time energy of an utterance with percent overlap as an input variable. As I referred to the short time energy equation it can be represented as square summation of ...
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1answer
76 views

Is there a closed form expression for main-lobe width increase given a window?

We know that when we window a signal, we increase the main-lobe width. Let 'main-lobe-width' here be the null-to-null bandwidth of the main lobe. Let us further more say that the main-lobe width of a ...
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198 views

Convolution in the frequency domain

We often hear that "convolution in time is the same as multiplication in frequency", and vice versa, that "convolution in frequency is the same as multiplication in time". So in a typical windowing ...
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90 views

What is the difference between Filters and Windowing?

I'm finding some difficulties to understand the difference between Filters, and Windowing. accoriding to my understanding both filters and window functions will make changes to the input signal ...
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How to acquire the `mainlobe` width to be less than the separation between two components that we wish to distinguish?

How does the mainlobe width of your window affect your ability to resolve the two components? Suppose a safe choice is to ...
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186 views

FFT - Effects of Windowing,Improvisation approaches on RealTime FFT Hardware

Fore-word :Kindly Observe this question has multiple updates take the latest update as question ! here below is my 256pt FFT on an 2Khz sinusoid signal,on a fixed point DSP tms320c5515 please ...
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52 views

STFT - Stride the windows?

In matplotlib's spectrogram function, this is how they "seperate and overlap windows": result = stride_windows(x, NFFT, noverlap, axis=0) What this is doing: ...
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62 views

STFT - Putting it all together

I'm currently reading this paper: http://www.rssd.esa.int/SP/LISAPATHFINDER/docs/Data_Analysis/GH_FFT.pdf On page 21, it has a section called "Putting it all together", it states the following ...
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394 views

Effect of Hanning Window on phase of FFT

I'm calculating the beat of song through the frequency domain. I have 60 seconds of audio sampled at 48000Hz, multiplied by a Hanning window in the time domain. This gives me a resolution in the ...
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42 views

phenomenon when window size for STFT is too short

Hi I was researching on STFT when I encountered this slide online I don't understand the points, Can anyone explain them? Thanks in advance.
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81 views

gabor wavelet and gabor transform

I was reading a paper 'A Flexible Framework for Local Phase Coherence Computation' (paper URL) on using wavelets for local phase coherence. I just want to be sure. Is the gabor wavelet the same as the ...
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233 views

Zero-pad before or after windowing for FFT

What's the correct way. Should I zero-pad a signal before or after applying a windowing function?
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245 views

Working around FFT windowing?

I have the following problem, that I ran into recently, when calculating the spectra of data that I obtain from a measurement technique, we are using in our group. In short what we do in the ...
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3answers
613 views

Choosing the right overlap for a window function

On Wikipedia there is quite a list of window functions. However, when you are doing a lot of STFTs, you often have to have some overlap to get better results. Generally an overlap factor of 2 (i.e., ...
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5answers
146 views

To what extent can we see signals that fall between frequency bins?

I have a simple problem I would like to figure out for fourier analysis of seismic data. Let us say that we have a signal $z[n]$, of length $N$. If I take its (same size) FFT, I will get $Z[k]$, ...
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123 views

Short term energy signal explanation

I'm trying to calculate the short term energy of a digital signal in python, using a rectangular window, but don't understand the basics of how this works, a pointer to any good explanation would be ...
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1answer
73 views

frequency components of discrete Gaussian-windowed signal

When we are do a discrete Gabor transform on a 1D signal, we apply a Gaussian window on a segment of the signal. However, due to the tapering ends of the Gaussian window, the magnitude of the data ...
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59 views

How do you choose a size for a windowing function in FFT?

How does one choose the proper windowing function to apply in an FFT? What are the benefits of larger sizes and smaller ones? Which would be the best for pitch estimation? Also which window function ...
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Why should one use windowing functions for FFT?

So I just revised my pitch calculation algorithm using a harmonic product spectrum algorithm. I was just curious about why this explanation of Harmonic Product Spectrum states that you need to ...
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1k views

Split audio signal into frames, apply window function and merge again

First off: I'm really new in the signal processing department and MatLab as well, so please bear with me here. What I want to achieve is to split my audio signal into smaller 25ms frames, where the ...
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313 views

Relationship between frame rate and sampling frequency in speech signal processing?

While I was going through the short time processing of speech signals, I got stuck at the relationship between the frame rate and the sampling frequency. Is there any relationship between them for ...
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1answer
107 views

STFT zeropadding

I am trying to implement the STFT by MATLAB, and I read somewhere that we must do zeropadding to the subsequence of the signal before windowing it with a Gaussian window. What happens if we don't do ...
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500 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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1answer
132 views

What is the physics behind the width of a main lobe?

We know that the square window gives the lowest main lobe width possible, and that other windows after that trade main lobe width for side lobe height. I also understand that the main lobe width is ...
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72 views

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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73 views

What is the correct way to calculate multi-taper estimates of spectral coherence?

I am trying to calculate the spectral coherence for two time-series using the multi-taper method. I am currently using Kiss-FFT to perform the Fourier transform. For calculating multi-taper ...
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283 views

Is the discrete Gaussian kernel an eigenfunction of the DFT?

So the Gaussian function is an eigenfunction of the Fourier transform because it transforms into itself, right? But this isn't true for the sampled Gaussian in the DFT because the tails of the ...
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149 views

STFT - Window Functions

I'm looking for your opinions. I have obtained a Speech Signal and computed a STFT on this signal. I have split the signal into blocks of (100 x 256) and computed the STFT based on different ...
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1answer
214 views

Matching masked images

Let's say I have two images that are parts of the same bigger image, cut using two masks (for simplicity, let's assume that the masks are just rectangles of the same size). The images are presumed to ...
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1answer
580 views

Frequency response <-> Impulse response

I am trying to calculate an actual frequency response from a desired frequency response. fftSize = 128; fs = 8000; I have 2 input arrays: f[] and aDesired[], ...
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7k views

How to apply Hamming Window?

I am new in matlab and signal processing. The time series that have been used are obtained from accelerometer in a building. As far as I understand both the time series' length and window function ...
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218 views

Intuitively, why is windowing function a low-pass filter?

I'm trying to intuitively understand why a windowing function of a signal is a low-pass filter. I know its DTFT is a sinc function, making it mathematically a low-pass filter, but my logic says ...
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Why do we use window in time domain rather than do FFT modify the spectrum and than inverse FFT

I thought that DSP would be done by using FFT of portions of a signal, modify the samples that result from FFT (since they represent the spectrum of our signal + noise) and remove any unwanted signals ...
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3answers
2k views

Effect of windowing on FFT magnitude

I have 2 sin waves: Fs = 1500; N = 100; t = (0:N-1)'/Fs; sinwave = sin(2*pi*15*t); sinwaveshifted = sin(2*pi*15*t + 1.3); If I get the magnitude at 15Hz using ...
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1answer
205 views

how do windowing functions not distort the signal?

I'm trying to gain a better understanding of windowing functions, but so far I can't tell why they're used. As an example, I'm familiar with the Hamming Window: $ w(k) = 0.54-0.46cos( ...
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3answers
253 views

best window for close frequency components

I'm currently designing a receiver which has to determine whether a signal contains specific frequencies or not. The frequencies are at constant 215Hz difference: ...
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215 views

PSD of Windowed signal

Suppose PSD of a signal $x(n)$ is $ PSD_{xx}(w)=1$. Now if a window function w(n) of length $ 0\le n \le N-1$ is applied to $x(n)$. what will be the new PSD?
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170 views

Applying Window Function to Low Frequency Signals

I'm computing 1 sec. hanning windows from a signal that has a variable frequency between 1-4Hz. My first impression is that data loss caused by the distortion due to the window function is greater ...
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1answer
427 views

Effect of Windowing Function on Autocorrelation Function

I need to compute FFT components and autocorrelation of a discrete signal. When I do not use any window function before taking FFT of the signal I get a reasonable AC function from FFT that includes ...
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1answer
151 views

Channel Vocoder producing output with “click” sounds

I'm trying to make a channel vocoder that takes two inputs, one a frequency rich carrier (a musical sound) and the other a modulator (vocals). Applying operations involved in the channel vocoder ...
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484 views

A few questions about Slepian and generalized gaussian windows

I'm trying to add documentation for all the window functions in scipy.signal, and I'm stuck on the Slepian (same as DPSS?) and Generalized Gaussian windows, which I'd never heard of before. There are ...
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757 views

FFT with asymmetric windowing?

Common non-rectangular window functions all seem to be symmetric. Is there ever a case when one would want to use a non-symmetric window function before an FFT? (Say if the data on one side of the ...