In signal processing, a window function is a mathematical function that is zero-valued outside of some chosen interval.
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91 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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5answers
207 views
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
96 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
65 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( ...
2
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3answers
141 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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2answers
140 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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2answers
117 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 ...
2
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1answer
150 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
102 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 ...
9
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1answer
213 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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2answers
391 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 ...
6
votes
3answers
340 views
What is a good FFT window function to reject DC?
I'm using an FFT to analyze what is essentially the power envelope of a signal (see here for info on the containing project), and, since power numbers are always positive, to eliminate the DC ...
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3answers
183 views
I need advice about how to make an audio frequency analyzer
I just need some clarification of some very basic aspects of creating a frequency analyzer. I am writing a c++ program, so far it is just a media player, with a custom explorer. You can make ...
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votes
2answers
705 views
How do I apply a function window to a signal?
How can I apply a window function like Hamming or Lanczos to a signal, using its coefficients?
I mean, which method can I use to do this? FFT? Convolution? Which method has the better performance?
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votes
1answer
244 views
Spectrum Analysis using Windowed FFTs
I have a couple of questions regarding windowed FFTs:
1) Why is the noise floor higher with windowed FFTs (according to Wikipedia's spectral leakage page, anyway), when the whole point of windowing ...
4
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2answers
275 views
Whats the optimal window function to use for analyzing real-time data samples?
Say you wanted to run a X point FFT on the last X audio samples that were played. The problem being, using a normal hann window function would place emphasis on the "middle" of the audio sample. ...
6
votes
3answers
1k views
RMS calculation in frequency domain after windowing
I can calculate RMS in frequency domain as derived from Parseval's Theorem.
But what if I have applied a windowing function before doing the FFT (in my case a Hann window)?. Now the RMS values are ...
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3answers
949 views
What should be considered when selecting a windowing function when smoothing a time series?
If one wants to smooth a time series using a window function such as Hanning, Hamming, Blackman etc., what are the considerations for favouring any one window over another?
