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

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What windowed Sinc might be closest to a Parks–McClellan low-pass filter?

In another question on dsp.stackexchange, a statement was made that the output of MATLAB firpm() or firls() for an anti-alias low-pass filter was "close" to the coefficients of a windowed-Sinc ...
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11 views

Dolph-Chebychev window and Beam Steering

We have made a Doppler sonar which is comprised of a braodband transmitter and an 8-element receiver arranged linearly. We collected some data at 500 kHz. I would like to steer the beams and apply a ...
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93 views

Power Spectrum in dBFs

I'm trying to get the spectrum of my signal in dBFS units. I'm not sure what is the refernce that I should devide by. I computed the power spectrum as follows: 1) FFT normalized to the number of ...
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1answer
36 views

What is the cause of slow roll off of windowed filters

Exactly why using the of windowing function, such as Hamming or Blackman, causes a slower transition to stop band? Everywhere it is mentioned just as an obvious fact that this happens but I haven't ...
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30 views

Audio output distorted with any FFT Windowing other than rectangular

For an experiment i have a simple application that takes a quadrature signal from a radio and then does the following: Complex FFT -> Inverse FFT -> Cartesian to Polar -> audio out If I tune the radio ...
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32 views

Subsampling data: terminology

I'm writing software and the data reporting frequency is slower than the acquisition cycle, so effectively sub-sampling is being done. Different data types require different methods of sub-sampling ...
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49 views

segmenting an EEG data

I have an EEG labeled data, which is the data that used for training, And I want to segment those data based on the time of EEG signal (Time-based Epoching) as a preprocessing step, based on the ...
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2answers
86 views

Computing main lobe width of Hamming window in Matlab by plotting

I wanted to verify the fact that main lobe width of a Hann/Hamming window is twice that of a rectangular window, using Matlab. I computed the analytical expressions for the respective frequency ...
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65 views

Increasing the number of points in the frequency spectrum

I have an image with few pixels in length and height. For this image I calculated the two dimensional Fourier transformation. What I got for the frequency spectrum in one direction was a very ...
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1answer
80 views

How should I select window size and overlap?

I'm new to DSP and I have a wav file with a number of different frequencies playing at different volumes. I'd like to plot the power of the 350Hz frequency signal at each point in time. The source is ...
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20 views

Relation between Gaussian and Savitsky-Golay kernels

I would like to make a mathematical comparison between two methods in my field. One smooths with a Gaussian filter, and one smooths using a second-order Savitsky-Golay filter. Let's say the window ...
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36 views

Window function for signal with 3-5 sine waves inside

Should I apply some window before FFT if i want to find 5 frequencies in signal? Signal is pure 5 sinusoids + some noise generated during trecording on analog cable.
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49 views

What is the relation of the transition band's width and the filter order for the FIR windowing method

When designing an FIR filter using the windowing method, how can one estimate the filter order ? It's obvious that the type of window and the transitions band's width has some effect on the order.
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124 views

Why are there so many windowing functions?

Many windowing functions are listed here in the Mathematica documentation. I tried using a few to reduce leakage when computing a Discrete Fourier Transform. From what I could tell it made little ...
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2answers
59 views

Fixing my FFT Plot

I'm trying to plot my FFT of File. This i my result. I made my FFT application: I want to obtain something very similar to plot of WaveSpectra, please tell me my mistakes.. My FFT The result from ...
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2answers
119 views

Is it necessary to apply some window method, to obtain the FFT? Java

I read that the window is needed to apply filter (Low Pass, High Pass, Band Pass or band Stop), but not for the FFT. 1. What advantage does apply a window or disadvantage does not apply? 2. What ...
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64 views

BandPass and StopBand FIR filters (Hamming) is not working

I have two groups of 3 frequencies of tone (music), First Group Tones: 39 (77.7817 Hz), 40 (82.4069 Hz) and 41 (87.3070 Hz). Second Group ...
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39 views

Extending 1D window functions to 3D (or higher)

(cross post of SO: http://stackoverflow.com/questions/27345861/extending-1d-function-across-3-dimensions-for-data-windowing ) For the sake of image (volume) registration, I'd like to apply a ...
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1answer
90 views

STFT: why overlapping the window?

For STFT, we impose window of certain size onto the original signal, then we perform fft on each window. The uncertanty about frequency and time is determined by the width of the window, however, I ...
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15 views

Short Time Fourier, What happen when window is outside the sample points

I am trying to compute STFT on the following signals..... such that they have 15 cycles of (1/50) second sine wave, with Fs=10000. The algorithm for STFT I am using is :STFT algorithm Then I set ...
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57 views

Reducing latency due to FFT windowing for a real-time signal

I need to compute the amplitude of a certain frequency band as the input to a PID algorithm. My system looks like this: ...
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2answers
95 views

Where do we use windowing?

I have been studying about the box window and am unable to understand one thing, do we first sample a signal and then window it resulting in up-scaling or downscaling, or is windowing a practical case ...
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1answer
128 views

FFT on Hamming Window Function [duplicate]

I want to apply Hamming window function the Audio sample then find out its fft.. ...
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44 views

Hanning Window Formula - Matlab didnt work

Im trying to do the Hanning Window manually but didnt work, what Im doing wrong? t=[0:.1:10]; x=.5-.5*cos(2*pi*t/102); plot(x); Not sure why I cant obtain the ...
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1answer
87 views

Spacing between gaussian windows for STFT

I'm computing discrete short time Fourier transform. Data is split into overlapping chunks and gaussian window is used for each chunk. However, I'm not sure how much overlap there should be between ...
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319 views

Is it customary to correct for the gain of a window?

Consider how the Hanning window is defined: 0.5 - 0.5 * cos(n*2*Pi/(N-1)) By this definition, it has a gain of 0.5, which is simply the average value of the ...
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28 views

Overlap-windowing vs preserved information

When windowing non-overlapped segments of data stream, part of the data is being "ignored" at the boundaries of the segments due to the tapering of window functions (non-rectangular). Some information ...
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99 views

Why are window functions used when calculating spectral estimates, really?

Having just read the rather long article on Wikipedia about window functions, I still do not see the mathematical point in using window functions when calculating spectral estimates (using e.g. ...
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113 views

Slepian or DPSS window

I am planning to use Slepian or DPSS window in my application where I want central lobe to be concentrated and also have low bandwidth: ...
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39 views

Using the windowing Method

I'm trying to write a C program that can get the PSD of an recorded audio file, I'm using for the fftw3 library. I wrote a program that calculate the PSD so far ...
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1answer
608 views

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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2answers
178 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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1answer
181 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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1answer
367 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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92 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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3answers
301 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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3answers
244 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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151 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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88 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
110 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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1k 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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332 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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4answers
263 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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2answers
69 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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895 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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1answer
46 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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1answer
147 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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686 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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337 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
1k 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., ...