Questions tagged [window]
The window tag has no usage guidance.
0
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1answer
34 views
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, ...
2
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1answer
74 views
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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0answers
33 views
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?
1
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2answers
57 views
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 ...
0
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2answers
28 views
Frequency Resolution Problem
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 ...
0
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0answers
8 views
Overlap-Add for 2-dimensional windows
I understand how overlap-add works for 1-dimensional signals, but I need to do something similar in 2 dimensions. The paper at this link covers the 1D case pretty well (see p29):
http://edoc.mpg.de/...
0
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0answers
37 views
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 ...
0
votes
1answer
23 views
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 ...
2
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2answers
92 views
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 ...
1
vote
1answer
309 views
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).
\...
4
votes
3answers
1k views
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 ...
0
votes
1answer
208 views
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 ...
1
vote
0answers
98 views
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, ...
1
vote
2answers
217 views
Short length windowed sinc filter
I have a 50-60Hz signal being sampled at a frequency of 25 kHz & I'm trying to filter all frequencies beyond 70 Hz with a reasonable steep transition band (approx 4 Hz) & good attenuation (~40+...
1
vote
1answer
339 views
Gaussian window and standard deviation
I am trying to figure out how to use the matlab gausswin function which constructs a Gaussian window for $N$ samples with a given standard deviation $\sigma$. The function is defined by
...
0
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3answers
1k views
Window period(overlap) and FFT
How does changing the window period (i.e the number of points overlap between two frames) affect the FFT results ?
Suppose that a time series signal was converted to frequency domain by FFT with ...
0
votes
1answer
200 views
fft - spectral leakage from noise into target frequency?
I have an acoustic setup. A sender, emitting a clean sine signal. The receiver is far away. In the time domain, the sine is hardly visible because the noise is nearly as big as the signal. In the ...
-1
votes
1answer
75 views
Should I use window or any filtering to average my data?
I have 80 seconds of data and I have to score my data by taking the average or median (or some other method) every 10 seconds. What's the best way to do this ? Should I just use a regular rectangular ...
-1
votes
1answer
73 views
On-Chip DFT Engine vs Software DFT
I'm new to signal processing. I'm trying to build a network analyzer. So far I was only considering getting the output signal through a 16-bit ADC and then do its corresponding windowing and DFT to ...
1
vote
2answers
511 views
Hilbert transform with a sliding window
I have a input voltage signal which has disturbances present in it. I am actually discretizing the input signal into say $1300$ samples and taking Hilbert transform of the signal by taking $N$ samples ...
1
vote
1answer
44 views
Should zero element be considered to calculate mean when smoothing spectrogram by window?
My (mass spectrometry) spectrogram does not measure the intensity constantly. I obtain the spectrogram, for example,
...
1
vote
4answers
245 views
What do I lose when I set overlap rate to a really high value in STFT
If I don't care about computational cost, is there any cons when I put overlap rate really high in STFT?
2
votes
1answer
753 views
How is a signal multiplied with the window functions?
How the input signal get multiplied with the window functions like Hamming, Hanning, Blackman, etc?
I have tried to multiply the input signal of $10\textrm{ MHz}$ sampled at $100\textrm{ MHz}$ using ...
0
votes
2answers
2k views
Understanding overlapping in STFT
I understand the concept of the STFT. In order to avoid spectral leakage, you use a Hann window that overlaps by 50%. However, the problem that I have, is that the example code online does not account ...
1
vote
1answer
892 views
Inverse the Hanning Window [closed]
I am using the following formula to calculate the Hann values for a set of points:
$$
w(n)=0.5\left(1-\cos\left(2\pi \frac nN\right)\right)
$$
To implement this in java, I am using the following code:...
3
votes
2answers
147 views
Zero padding - High amplitude
I have a set of 512 samples that I have collected with a sensor. I'd like to apply zero padding to it, for better frequency bin resolution. However, all the tutorials I see to make this occur center ...
0
votes
1answer
1k views
Overlap and windowing a signal for signal processing
I’d like to digitally signal process an audio data. Therefore my idea was to:
Split the audio data into individual blocks of 16 samples each.
Each block has an overlap of 50% (8 samples are shared ...
0
votes
2answers
444 views
What is a “square window function”?
When I read previous studies it mentioned a method of "square windowing function". I searched but I did not find anything talking about it. Can someone help to explain what is "square windowing ...
1
vote
2answers
158 views
Non-symmetrical DFT of real valued signal
I have a homework assignment to take the $64$ DFT of $\cos((5\pi/32)n)$ and $\cos((5\pi/64)n)$. However, for the second case I obtained DFT spectrum such that I have that famous symmetry in real part ...
1
vote
1answer
250 views
Is information lost due to Hanning window perturbations?
I apologize for the obscure phrasing of the title of the post...My question is quite simple...
Let us imagine an audio signal (any song will do). We want to apply the Short Time Fourier Transform ...
0
votes
1answer
130 views
Hamming Window LUT function
I'm working on a project where I need to generate a LUT for Hamming Window to perform a FFT.
I'm using this function (doing the table with MATLAB):
...
0
votes
2answers
128 views
What happens if you apply window after filtering a discrete signal to get it back to its original length?
What happens if you filter a discrete bandpass signal of length $N$ with a bandpass filter(Hann truncated sinc) of length $L$ and apply a window of length $N$ to the filtered signal of length $N+L-1$ ...
4
votes
2answers
5k views
Why is each window/frame overlapping?
I am currently reading up on some speech recognition theory.
As it speech signals usually are non stationary, but if a speech is seen in a very small time frame can it be deemed stationary, as would ...
1
vote
0answers
28 views
Where can I find more information about this formula relating a window's time and frequency size?
I remember having seen a formula of the form
$C=\frac{B}{L}$
that relates a duration $L$(s) of a window to its width $C$(Hz) in the spectrum (defined at -3dB or so). The constant $B$ would be ...
2
votes
0answers
44 views
Separating out a sequence of DFTs with overlapping windows
Suppose I have a time series partitioned into $N$ equally-sized sections. Choosing some $k<N$, for each of the sections $i \in[0, N-k]$, I concatenate that section with the $k-1$ sections to the ...
1
vote
1answer
144 views
Why do we not use square filters without windows? [duplicate]
This question may sound like "why do we use window functions", but it's not. So here it's:
What we currently do: If we have a function $g(t)$ and its Fourier transform $G(f)$, and a window $W(f)$ and ...
1
vote
1answer
97 views
Why does my plot of the Blackman window not match everyone else's in literature?
I've seen the plot for Blackman window as so in a bunch of books, as on this website:
But plotting the same equation on Wolfram Alpha yields a different plot:
Why is their graph not centered around ...
1
vote
1answer
406 views
Is an FIR filters 'transition width' frequency dependent?
I was recently brushing up on some FIR filter design and was browsing the Wikipedia page. A claim in the article caught my attention:
The main disadvantage of FIR filters is that considerably more
...
0
votes
1answer
47 views
What does the 'B' parameter represent in Wikipedia's page on window functions?
I was trying to learn some more window functions and was referencing the Wikipedia article on the subject. I've noticed on a lot of the plots, there appears to be a capitalized and italicized letter B....
0
votes
1answer
355 views
MRI reconstruction using windowing based apodization
I am trying to apply windowing to do MRI reconstruction. I have a 256 point one dimensional k-space samples which look as follows:
Here, the real part(green) is flat around 0 and the blue curve is ...
0
votes
1answer
374 views
Integer and a half periods of sine wave in DFT window
Why does a pure sine wave starting and ending at 0 in the sample window of a DFT but containing 1.5 cycles (or periods) produce the same spectral leakage (i.e. not more) as a pure sine wave with ...
0
votes
2answers
156 views
Bandpass Filter Order vs Sample Numbers of Noisy Signal
I'm working on signal filtering in MATLAB. i wrote sample code that generate 50 Hz signal with some noisy frequency and use Kaiser bandpass filter to get only 50Hz frequency. this code work great! but ...
3
votes
1answer
125 views
How to calculate a Hann-LP kernel for image processing
I'm currently studying for an exam in image processing and stumbled upon a exercise which i could not answer and my professor will not be available before the exam anymore. The exercise goes as ...
5
votes
1answer
189 views
What is the LOW frequency resolution rule analogous to Nyquist?
If I'm analyzing a signal in the frequency domain, I know about the well known Nyquist criteria that the sample frequency must be > 2x of the highest component present in the signal.
However, there ...
0
votes
2answers
1k views
finding the fundamental frequency in frequency domain
I want to get the fundamental frequency of a signal. I used a time domain approach first. It just sums up the differences between the signal (lets say 2048 samples) and the delayed version of the same ...
1
vote
1answer
201 views
Design a FIR filter with a Kaiser window
Here is the exercise I am working on.
Use the window design method with the Kaiser window to design a linear phase high pass FIR filter of minimum order that meets the following specification:
$\...
5
votes
3answers
13k views
Moving average vs. Moving median
I have read in many places that Moving median is a bit better than Moving average for some applications, because it is less sensitive to outliers.
I wanted to test this assertion on real data, but I ...
0
votes
1answer
512 views
Why does the Hamming window attenuate the FFT?
I am working on a very simple voice recognition system using the msp430. In my research I've read that for real life audio signals its necessary to apply a window to the FFT data because the audio ...
1
vote
1answer
131 views
Non-separable, higher-order generalized cosine windows in 2D for images
Higher-order generalized cosine windows define a useful parametric family of windows functions, embedding Hamming, Hann, Blackman, Nutall, etc.:
$$w(n) = \sum_{k = 0}^{K} a_k\; \cos\left( \frac{2 \pi ...
1
vote
1answer
263 views
How is the ends of a bandpass filtered signal reliable after applying the cosine taper?
A taper function decaying to zero at ends such as a cosine window is routinely applied to the signal before bandpass filtering to reduce end effects. Obviously the window alters the waveform.
So, as ...
