Questions tagged [window-functions]
In signal processing, a window function is a mathematical function that is zero-valued outside of some chosen interval.
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Advantage of applying a Window Function in Analysis and Synthesis of STFT?
I'm studying Short-time Fourier Transform and I learned that if you apply a windowing other than rectangular, you need to overlap the frames---for example, 50% overlap for Hamming family---to ...
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23 views
Synthesis of 75% Window Overlap Add method for Short-Time Fourier Transform (STFT)
I'm doing the overlap-add method for STFT and I quite understand the implementation if it's a 50% overlap (where I add the 2nd half of the previous frame to the 1st half of the current frame during ...
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0answers
18 views
Pandas resample.mean()
I have a question to all you filter experts out there. I have some engine data sampling irregularly at about 50Hz. Recently I've been downsampling via the Pandas resample().mean() method. Basically ...
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2answers
57 views
spectral leakage for integral number of periods
I'm attempting to understand spectral leakage and read the following quote on wikipedia:
Windowing a sinusoid causes spectral leakage, even if the sinusoid has an integer number of cycles within a ...
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0answers
36 views
How to applly Hanning window on S parameter results?
I am working on Time domain computation. I have S parameter results simulated, using these results I do the Inverse FFT to get results in time domain.
I want to filter/window results using Hanning ...
0
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1answer
32 views
Recoverable continuous function after average sampling
I have a personal interest in this question, but I don't know if it is unfounded.
Suppose I have a continuous function x (t), which is sampled using an average sliding window, which performs a ...
2
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1answer
97 views
Does spectral leakage include negative frequencies?
When choosing a window function, window duration, and/or transmission frequency (assuming sampling rate satisfies Nyquist), one may want to understand what sort of spectral leakage would occur at a ...
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0answers
28 views
Why is the coherence function unity at all frequencies when only one reading is done?
Several papers on the internet states that the coherence function is unity for all frequencies if only one reading is done, and that the coherence function requires an average of two or more readings ...
3
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1answer
113 views
FFT strong signal in middle frequency bin
I've developed a radar that I'm using to determine the distance to remote objects. It uses a custom PCB with an onboard FPGA that performs the DSP algorithms. The data from it is then plotted on a ...
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1answer
39 views
Python window funtion implementation [closed]
Can you help me implement window functions in python?
I have to write functions for following windows:
rectangular
triangular
hamming
hanning
blackman
parzan
Thank you in advance
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1answer
54 views
When can a windowed cosine be considered band-limited signal?
I have an exam in the following days and i have no clue of what is the response to this question in the exam:
given this signal:
$$g(t) = H\left(t+\frac{T}{3}\right) f(t) - H\left(t-\frac{2T}{...
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1answer
57 views
Correctly scaling FFT of different lengths
I have been looking at using two FFTs of different lengths and displaying the output magnitudes on the same graph (a shorter length window for the higher frequencies, and a longer one for lower ...
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30 views
How to applying window function to get same result with pwelch in MATLAB
I'm trying to calculate the power spectral density (PSD) to analyze signal power. To do so, I wrote a MATLAB code with the great help of others and below is my code.
...
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230 views
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101 views
Can Kaiser's formula be used to estimate the filter length of an FIR filter for all windowing methods?
I came across this problem while designing a FIR filter for given $\omega_p = 0.4\pi$ and $\omega_s = 0.6\pi$ along with the minimum stop-band attenuation $\delta_s$.
I have worked out some examples ...
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0answers
41 views
Magnitude attenuation by a filter
I have a filter, with coefficients given by W=sin((2*pi*2*Ff*k/Fs)/(2*pi*2*Ff*k/Fs))*h(k), where Ff is the filter reference frequency, k runs from -N/2 to N/2 (N is the order of the filter), Fs is the ...
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2answers
103 views
STFT on time varying signal with good time and frequency resolution
I am trying to determine the main frequency of a noisy signal that varies in frequency over time. Ideally I want to detect changes in the frequency as rapidly as possible - say 50Hz update rate, but I ...
2
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1answer
278 views
Why is the Hamming and Hanning window the most widely used for speech spectograms?
When taking the Short-Time Fourier Transform of the speech signal, windowing is applied to taper away the signal frame at both ends and mitigate introduced artifact at expense of the maximum ...
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1answer
90 views
Cosine window function & signal with nonzero mean
I'm using cosine window function of order $p$:
$$ f(t) = \frac{2^p (p!)^2}{(2 p!)} \left(1 + \cos(\pi t)\right)^p $$
for frequency identification in real signals with several frequency components.
...
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1answer
119 views
Can the Hanning Window be represented in the time domain
I know the Hanning window, $w_{Hann}(n) = 1 - \cos \left(2\pi \frac{n}{N} \right)$, is typically applied to discrete Fourier transforms. $N$ being the total number of points in a transient signal that ...
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0answers
37 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 ...
0
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1answer
628 views
Comparison of results own implementation and python signal.welch
I am trying to replicate the output of Python's signal.welch function to make an estimate of the PSD from an FFT calculation. I don't want to use the built-in function to understand better what is ...
0
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2answers
76 views
How can I graph the amplitude for a given frequency window over time?
I have simple audio files of single plucked notes from a guitar:
I want to graph the amplitude of each partials over time, rather than just have this color-coded "dB" intensity graphing I have here.
...
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2answers
109 views
How exactly does one apply a Hanning Window for a spectral estimate?
PREAMBLE
I am a graduate student researching evolutionary ecology. My supervisor and I have been trying to learn how to simulate colored noise, discretely, by the $\frac{1}{f^\alpha}$ power law for $\...
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3answers
136 views
How does a rectangular window affect the signal?
If i am not mistaken a rectangular window of length 10 gives us an array of 10x1:
1 1 1 1 1 1 1 1 1 1
And if we apply this to a signal we are left with exactly ...
0
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0answers
40 views
How to relate power spectral density with the number of resource blocks in LTE?
I am running a simulation with 100 Resource blocks for LTE OFDM and I plotted a PSD for it. Now I am able to bring down the out of band emissions when I perform an algorithm on it. Based on the ...
2
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1answer
997 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?
2
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1answer
202 views
Purpose of multiplying fft output by Hann window?
I'm working with some acoustic propagation models at the moment.
A feature I've noticed in 2 of these models is that the output of the model is often multiplied by a Hann window in the frequency ...
4
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1answer
60 views
Amplitude Estimating Using a Windowed DFT
Let's say we want to estimate the amplitude A of a mono-frequent signal using a windowed DFT. The frequency of the signal is unknown, and the frequency resolution of the DFT is limited, thus it cannot ...
0
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1answer
38 views
Why does shortening window widen its Fourier Transform?
On page 76 of the book Discrete Time Speech Signal Processing by Thomas F.Quatieri, the author states "shortening the window widens its Fourier Transform".
Can anyone explain why?
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0answers
49 views
Attempting to remove the 60Hz frequency out of a noisy ECG signal
load eeg_plus_noise
Fs=200;
Fn=Fs/2;
b = fir1(64,[59.8 60.2]/Fn,'stop');
figure(3)
freqz(b,1,512,Fs);
y = filter(b,1,eeg_plus_noise);
I am then using the ...
0
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0answers
78 views
Windowing in frequency domain. how to cut a spectrum using window function in frequency domain?
I have a set of measurement data of a FMCW radar and trying to estimate the system transfer function. In the frequency spectrum, I can see multiple peaks due to the non-linearity that exist in the ...
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1answer
52 views
Quantized error in scatter plots for a hamming windowed LTE signal
I have a time domain signal based on LTE standards.
Carrier spacing = 15KHz, Symbols per slot = 6, extended Cyclic Prefix = 512 samples
FFT size = 2048, No. of sub carriers = 1200, channel BW = 20MHz, ...
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2answers
215 views
What version of sinc function to use ? (With additional factor of $\pi$ or not.)
I have an exam tomorrow on Signal Processing and one of the questions can go two ways:
Use a Hamming window to design an Nth
th order (N+1 tap) band pass FIR filter with a pass-band
between $f_0$-$...
0
votes
1answer
51 views
I have the scatter plots for a Hamm and Tukey(0.25) windowed data. The complex data plotted from Hamm windowed forms a pattern, why?
The Hamm windowed complex data forms some sort of a quantized pattern whereas in the same code if tukeywin(0.25) is applied normal noise is observed. Any idea why ?
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1answer
49 views
How to window a time domain signal for 6 symbols with cyclic prefix length of 512 samples?
Based on LTE stds. I am running a simulation for 6 symbols (each having 1200 central subcarriers) each in a 2048 FFT/IFFT bin. To these symbols are appended 512 samples as cyclic prefixes. I have to ...
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1answer
40 views
Applying window function to reduce out of band emission for a symbol in LTE simulation?
I have to apply a window to an IFFT'ed signal (based on LTE standards, simulated for 1 symbol - 100 resource blocks - 1200 subcarriers). I have a signal which I have simulated till the IFFT. Now I ...
0
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1answer
266 views
Overlap/add time-domain audio frames: How does normalization/scaling work with overlap greater than 50%?
I am attempting to overlap-add time-domain audio frames in a real-time context (with a continuous stream of data coming-in). Each frames consist of 1024 samples and have been previously "Hann" ...
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0answers
53 views
Frequency bins too powerful at the start and at the end of each sample computed DFT data
I've taken the following link http://coding-geek.com/how-shazam-works/#comments as a project to start practising and learning signal processing and python programming for me to get started in speech ...
1
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1answer
281 views
Modified Periodogram function in MATLAB
Given below is a function written in MATLAB for computing the modified periodogram, taken from Hayes, Statistical Digital Signal Processing and Modeling
...
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2answers
110 views
Attenuate frequency bin in FFT array resulting in artifacts [duplicate]
Am trying to remove noise for certain frequency bands by attenuating freqeuncy bins in the FFT array. However this results in artifacts to be formed, where there are clicking sounds in between each ...
0
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2answers
306 views
Window length in matplotlib's specgram
In the paper about speaker verification I can read that
Two quantities have
to be set: the length of the window and the shift between two
consecutive windows. For the length of the window, two ...
1
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1answer
844 views
Seven term Blackman Harris window
I am currently trying to evaluate a high resolution ADC for which I need to window my output data for the FFT. Up until now I have been using the default 4 term Blackman harris window in MATLAB. ...
1
vote
3answers
102 views
how could window function really suppress those frequencies that we don't want?
I know we can use window function to decrease leakage phenomenon by making the end of a non-periodic signal to be zero at both end, so that to make it like "continuous and periodic" when doing fft.
...
1
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2answers
473 views
Linear Convolution in DSP and Hann window
My understanding is that when dealing with discrete finite sequences, convolution done thru FFT is circular. To obtain linear convolution, one would pad the input with zeros up some appropriate length....
2
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1answer
4k views
How to calculate the power of a discrete signal? / Clarification on PSD estimates
I want to calculate the channel power $ P_\mathrm{x}$ of a given discrete and complex signal $x[n]$ (with a length of N) in a given bandwidth $B$.
I'm aware, that I could probably apply a sharp ...
0
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1answer
353 views
Windowing a signal for FFT
I am actually working on a project involving the cross-correlation of two signals. My cross-correlation code is working fine, but I suspect that I should apply a window to my data set in order to ...
0
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1answer
75 views
Difference between applying a window to a whole signal and frames.
I'm going to do feature extraction using a speech signal.
The first step is the windowing of the signal using Hamming window.
I'd like to know if I should apply one single window to the whole ...
1
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1answer
303 views
Apply windowing before FFT or after?
I am computing a spectrogram and I've found a code example online which goes like this:
...
1
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1answer
71 views
Why is the raised cosine pulse for digital communications so popular?
The raised cosine pulse is essentially a windowed sinc function, designed with some roll-off in mind. Why do we use this particular window, as opposed to other windows such as Hann, Hamming, Kaiser, ...
