Questions tagged [window]

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31 views

Window function correction when using frequency domain likelihood

I was wondering if someone could tell me or point to resources which discuss what kind of of windowing corrections factors one should use when using a frequency domain Whittle likelihood for spectral ...
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1answer
55 views

What is the proper way to filter out unwanted noise from accelerometers?

I'm a beginner in signal processing and have a hard time to filter out environmental noise from the floor vibration data collected using accelerometers. I have tried using butterworth filter (IIR) ...
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24 views

what should the the output of an FIR filter (root raised cosine) look like?

I am implementing a filter that is FIR on verilog HDL ,, I understand what happen in the filter well, I mean the delay, multiply and sum, the problem that I can't imagine how can I get the desired ...
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13 views

FIR Kaiser Window Discrete Time Filter Design

Please look at Part (c) of the question. How do we know that the Filter is a Low-pass or High-pass and is the filter designed in C a multi-band-pass filter.
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1answer
38 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, ...
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1answer
149 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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34 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?
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2answers
67 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 ...
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2answers
33 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 ...
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14 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/...
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63 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 ...
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1answer
25 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 ...
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2answers
97 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 ...
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1answer
394 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). \...
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3answers
2k 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 ...
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1answer
225 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 ...
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0answers
117 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, ...
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2answers
256 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+...
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1answer
460 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 ...
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3answers
2k 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 ...
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1answer
226 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 ...
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1answer
87 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 ...
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1answer
89 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 ...
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2answers
583 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 ...
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1answer
48 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, ...
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4answers
284 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?
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1answer
918 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 ...
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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 ...
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1answer
1k 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:...
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2answers
158 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 ...
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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 ...
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2answers
507 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 ...
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2answers
186 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 ...
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1answer
287 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 ...
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1answer
134 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): ...
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2answers
134 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 $N+L-1$ ...
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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 ...
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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 ...
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45 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 ...
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1answer
157 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 ...
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1answer
105 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 ...
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1answer
432 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 ...
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1answer
48 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....
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1answer
393 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 ...
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1answer
422 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 ...
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2answers
159 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 ...
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1answer
137 views

How to Calculate the Hann Low Pass Filter / 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 ...
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1answer
197 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 ...
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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 ...
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1answer
207 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: $\...