Hi, I am trying to use Kaiser-Bessel window before FFT. However, I am a bit confused about what is the difference between Kaiser and...

Hi, I am trying to use Kaiser-Bessel window before FFT. However, I am a bit confused about what is the difference between Kaiser and Kaiser-Bessel window. There is a definition of Kaiser window: http://en.wikipedia.org/wiki/Kaiser_window and also definition of Kaiser-Bessel derived (KBD) window. According to this document, Kaiser and Kaiser-Bessel windows are the same: http://local.wa...

Hi all, My understanding is that FFT needs to operate on a window. If I want to look at the spectrum of a series data, I guess I have to...

Hi all, My understanding is that FFT needs to operate on a window. If I want to look at the spectrum of a series data, I guess I have to do a rolling-window, let's say N=256, The first window is from 1 to 256, and the second window is from 2 to 257, the third window is from 3 to 258, etc. For each window, I will have 256 numbers as the FFT outputs, What's the best way to present...

Hi, I've made a Blcakman window in Matlab with the...

Hi, I've made a Blcakman window in Matlab with the code: windowWidth=256; Window=(0:windowWidth)/windowWidth; Window=0.42-0.5*cos(2*pi*adaWindow)+0.08*cos(4*pi*adaWindow); This looks fine when I plot it, But Im not sure wether how to calculate the time derivative of it. An fft of the Window variable gives just a single peak and a flat line, and gradient(Window)*Fs doesn't look r...

Hi all. I'm playing a bit with window functions in filter design etc, and have come across a couple of gruelling expressions. More...

Hi all. I'm playing a bit with window functions in filter design etc, and have come across a couple of gruelling expressions. More specifically, the Chebychev window [1, eq. 5-17], the Tukey window [2, table 8.1] and the Lanczos window, [2, table 8.1]. I would like to know how one estimates the width of the main lobe for these filters, and how one uses the various control parameters....

I have some questions about length of windowing functions applied to 1D and 2D FFT. For a N point 1D FFT, it is very straightforward, I can...

I have some questions about length of windowing functions applied to 1D and 2D FFT. For a N point 1D FFT, it is very straightforward, I can generate a N point window function, and multiply it with the signal before doing FFT. But for N*N point 2D FFT, what length of window function should I use? Should I generate a N*N point window same to the one used in 1D FFT, or a N point window and repeat the...

I am studying a matlab function specsub.m,which perfom Martin's spectral subtrction method. specsub.m can be found in the lately voicebox. A...

I am studying a matlab function specsub.m,which perfom Martin's spectral subtrction method. specsub.m can be found in the lately voicebox. A new window usage attractted me and made me puzzle. what is charecteristic of the follwing window? Why use such a window? w=sqrt(hamming(nf+1))'; w(end)=[]; % for now always use sqrt hamming window w=w/sqrt(sum(w(1:ni:nf).^2)); % normal...

Is the triangle window pretty much lame or are there examples where the triangle window is the best window to apply to data prior to...

Is the triangle window pretty much lame or are there examples where the triangle window is the best window to apply to data prior to an FFT? Could anyone provide examples of when triangle window is the best choice?

On Friday, January 21, 2011 6:59:36 PM UTC-5, dbd wrote: ... > The window is how the user trades off locality and variance. It is an > ...

On Friday, January 21, 2011 6:59:36 PM UTC-5, dbd wrote: ... > The window is how the user trades off locality and variance. It is an > important tool in controlling the selected processing. It is useful to > put the window conceptually in the DFT because basis function values > outside the window are never calculated while the data values outside > the extent of the window are used.

I have done some experiments with a Gaussian window applied to real signals. The signals were pure sinusoids of a fixed frequency...

I have done some experiments with a Gaussian window applied to real signals. The signals were pure sinusoids of a fixed frequency and phase. I used this window: w(k) = e^( -(1/2) * (k - (N-1)/2)^2 / (a*(N-1)/2)^2 ) with N=32, k = 0, ..., N-1 and a = 0.265391249974779 I multiplied my signal with the window and did the DFT. Then I calculated the magnitudes around the peak. I took the...

I am trying to sample the magnitudes of a shifted window in the frequency domain. But I wonder what to do when a part of the window sits in the...

I am trying to sample the magnitudes of a shifted window in the frequency domain. But I wonder what to do when a part of the window sits in the negative frequency. Here is an example: if the window (ps. a real symmetrical, ie. H[-k] = H[k]) is centered at 80 Hz, and the sampling interval (the interval between two bins) is 43 Hz. These are the bins around the center of the window to be sampled:...

When making a filter for a time domain interpolation of a signal using a windowed sinc kernel, what should be the right way of aligning the...

When making a filter for a time domain interpolation of a signal using a windowed sinc kernel, what should be the right way of aligning the window towards sinc? I can think of three possibilities: 1) The center of the window could be set at 0. 2) The center of the window could be set to the value of the time domain shift of the interpolator. 3) The center if the window coul...

I'm smoothing some data and was wondering how to calculate the "width" of the smoothing window, to get an estimate of what the new resolution...

I'm smoothing some data and was wondering how to calculate the "width" of the smoothing window, to get an estimate of what the new resolution will be. Say i boxcar smooth with a window of 5 points, then obviously one can estimate the new resolution as being 5 points. If I have points in the window, in general as [a0,a1,a2,a3,a4,a5,a6,a7,0, 0,0...] where the a's are descending, how do...

This is a random question on a simple topic. Sorry if this is a little trivial. If you were to filter a signal with a windowed sinc...

This is a random question on a simple topic. Sorry if this is a little trivial. If you were to filter a signal with a windowed sinc filter, (using a Blackman window), would you get better results using a large 20,000 point window or a smaller 2,000 window? Consider the signal has no step functions or spikes, and it is a 250 sample per second signal. Consider the performance in the time domain ...

Hi all, I'm playing around with an audio level compressor and calculate the RMS value in a rectangular window. I'm quite new to this ( also to...

Hi all, I'm playing around with an audio level compressor and calculate the RMS value in a rectangular window. I'm quite new to this ( also to dsp programming ), but my questions are: - Is there an optimum size for the averaging window? The bigger the window the more true the average RMS will be, i think. But a big averaging window takes too much load on the processing power of my dsp. ...

I'm using pwelch to estimate power spectrum. Since a window is used by pwelch, then 1. if I should make the window size long enough or...

I'm using pwelch to estimate power spectrum. Since a window is used by pwelch, then 1. if I should make the window size long enough or equivalently the window mainlobe narrow enough to give an accurate estimate? 2. if I make the window size as long as 131072, the mainlobe width is less than 100Hz. How many sections are needed to make the estimate reasonably smooth? 8 or 16 sections seem to b...

Hello, I'm studying LP based coders but couldn't find proper explanation why non symmetrical window (half Hamming and quarter of cosine) is...

Hello, I'm studying LP based coders but couldn't find proper explanation why non symmetrical window (half Hamming and quarter of cosine) is used. Is it because of magnitude response or time domain shape ? What is scientific background to use of this window ? How could I evaluate performance of some other window sequences - any tutorials (preferably Matlab) available to do such evaluation...

Hi All, In Matlab there is Hanning function which implement cos^2(t) window. It has -18 db/oct roll off. I need to estimate the signal PSD...

Hi All, In Matlab there is Hanning function which implement cos^2(t) window. It has -18 db/oct roll off. I need to estimate the signal PSD using window with higer roll off. The sin^4(t) seems adequate for my purpose but it seems it is not implemented in Matlab? I wonder is there in Matlab window with roll off in terms of -30 db/oct implemented? Thanks! penev

Hi, I am trying to understand the difference between the sliding window FFT algorithm and the windowed FFT (i.e. the conventional...

Hi, I am trying to understand the difference between the sliding window FFT algorithm and the windowed FFT (i.e. the conventional method). Say we have a 6000 sample time domain data that we wish analyze in frequency. We can take two approaches: 1- Pad the data stream with 2192 zeros and apply a 8192 point FFT. 2- Choose a short window size (e.g 256 points) and slide this window acros...

Hi, I'm looking for the method to get the Rife vincent window or other windows constant value. Take for example Blackman window which has...

Hi, I'm looking for the method to get the Rife vincent window or other windows constant value. Take for example Blackman window which has below equation: w(n)=0.42-0.5cos(2*pi*n/N)+0.08cos(4*pi*n/N), 0

Hi all we are doing a voice verification project in MATLAB. I have done a pitch detection algorithm which is working ok ok depending on...

Hi all we are doing a voice verification project in MATLAB. I have done a pitch detection algorithm which is working ok ok depending on the length of the input as well the length of hamming window. Now for male input, the results are quite good if the window duration is 120-150 samples (sampling rate is 8 KHz) whereas for female voice i have to reduce window length to almost half if the voi...