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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Doubt regarding scaling of Welch Overlap Segment Averaging with Lomb Scargle

I am doing something similar to this question Comparison of results own implementation and python signal.welch. In my case there is no Welch method associated with the scipy lomb scargle spectrum so I ...
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How to generate a raised-cosine window with a specific roll-off factor in Matlab?

I have recently started working on signal processing. For a small project, I have to shape cosine signals using a raised-cosine window with certain roll-off factors in Matlab. To give you an example, ...
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Antenna pattern in frequency domain and Hamming window

I have an antenna pattern (azimuth cut) and I want to apply a Hamming window to it. In SAR processing the target is shaped by the azimuth antenna pattern, and on top of it it should be possible to ...
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Impact of STFT window function and FFT length on computation time

I have been doing a study which part of it includes a comparison of computation time vs window type and length (among some other things in the computation time, however I speak in terms of relative ...
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Sampling, filters, windowing, FFT. From theory to help on this coding list

My plan is to analyse the spectrum of samples from a microphone. I wonder how correct this suggestion is. The below description may then fail on several points. I am in need of somebody with a red ...
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Applying a window to a signal

How can I Gaussian or Bartlett window to a signal? On the other hand, is it a good way of smoothing signals? If not what are the differences between smoothing and windowing?
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FFT with High Time and Frequency Resolution

Can anyone describe in a bit more detail or provide references to the techniques for simultaneous enhancements to time and frequency resolution described in a high level in this video? Can anyone ...
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Low-pass vs. windowing function in front of FFT

I am sampling sound at 48 kHz because that's what the DAC for the headset needs. I take every 6th of these. So I have 8 kHz and process 1024 at a time. My goal is to analyse the spectrum in the final ...
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Complex Windows

Typically windows are symmetrical and real. Are there any applications where complex windows have been used (other than applying the same real window to the real and imaginary components of a complex ...
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Understanding spectral leakage in a pink noise dominated signal

I've been reading about power spectral density estimation based on the DFT, about spectral leakage, windowing functions and the Welch method. I've recorded a signal that's supposed to be pretty much ...
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normalize STFT output by magnitude

I am using torch.stft() to generate spectrograms for neural networks and come across the below code. ...
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Optimize window length (STFT) via gradient descent (in neural networks)

The authors from this paper optimized a Gaussian window size via gradient descent (the σ parameter of the bell curve) together with the other parameters of neural networks. I don't use Gaussian window ...
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Artifacts on frequency spectrum

I made a spectograpm in C that takes in a wav file (44.1kHz), converts it to 8bit pcm(can't go higher because of memory constraints) and does 1024 sample FFT on a number of bins, using Welch method. I ...
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Proof that the rectangular window has the best resolution

The resolution of a window is typically defined by the width of its spectral mainlobe (3dB-width or null-to-null width). It is often stated that the rectangular window has the best resolution among ...
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lopsided Hanning Window function

I am processing sensor signals and have been looking at using window functions to smooth out the signal before I conduct a fft on it. A normal symmetrical hanning function seems to disorientate the ...
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Graph Plot On Time Shift of Cosine Signal Hanning Function

I am plotting time shift of the Hanning function. I find few plot result that I am not able to understand. Therefore I would like to ask my question here. The given Hanning function is: $$ x(t)={\tt ...
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Under which conditions will windowing with a rectangular window intime always lead oscillations in the spectrum?

I'm going through some conceptual questions about windowing signals. I came across the following: Assume a sinusoidal signal - under which conditions will windowing with a rectangular window ...
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Direct calculation of the fft of a rectangular window

For a rectangular window defined as, the frequency spectrum equation and magnitude (or pseudo-magnitude) plot are, However, when I apply Scilab's fft() function or the definition of DFT definition ...
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Window with optimal sidelobes for a given ENBW / frequency-resolution

Is there a family of windows which is "optimal" in terms of energy above/below a boundary, but with controllable ENBW/bandwidth? By optimal, I mean maximising energy concentration inside ...
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sensor data windowing and normalization

I am getting up to speed with working with sensor accelerometer data. I am looking to conduct a FFT on this signal. I found that the signal being non periodic is causing issues so I have tried to look ...
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Plot of the Fourier transform of the Sine Window

In Wikipedia, a Fourier transform of the Sine Window \begin{align} w[n] = \sin \left(\frac{\pi n}{N} \right), \ 0\leq n \leq N \end{align} is plotted like below. However, I am not sure how to obtain ...
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Do we guess the cut off frequency when passband edge frequency and stop band edge frequency are given? FIR Filter design-LOW PASS FILTER

Say passband edge frequency=0.25 $\pi$ Stopband edge frequency=0.35 $\pi$ What is the cut off frequency? Do we average these 2 frequencies and write the answer or what is the procedure to find cut off ...
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Calculating Hann WIndow

Hey I have this CSV file which contains 8 chunks of 256 samples of a sine wave with different frequencies (each chunk has different frequency starting from 8 to 64Hz). The total samples of this file ...
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What is the effect on the cross-correlation of two windowed signals?

I've been trying to determine the effect of performing the cross-correlation operator on two windows signals. For example: suppose we have two Sinc functions. The Sinc function is defined as $\frac{...
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Faster way to Implement a CFAR (window average) Threshold

I implemented a version of a CFAR average in MATLAB but it's 'slow' and I need to speed it up. I included the pseudo code and logic below. I used a nested for loop to calculate the moving average but ...
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Mitigating high-frequencies after sampling

I have a dummy signal that I am sampling at $T = 100 \ \mu s$. According to the Nyquist frequency, I can identify frequencies up to $\pi/T = 31416 \ rad/s$, as we can see in the FFT of my signal (blue ...
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Biorthogonal Windows

I am starting to study about the concept of biorthogonal windows and the relation to (Discrete) Fourier transform and short-time Fourier transform (STFT). I have not found an introductionary review of ...
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Basic Question about Windowing in DTFT

I was reading this and it explains the various windows such as Rectangular, Bartlett, Hanning, Hamming, and Blackman. Specifically, I saw this graph comparison of their dB magnitude frequency response ...
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Integral of Kaiser window

I want to sample (evaluate at regular intervals) the integral of the Kaiser window. Is there a nice closed-form solution to this, so I don't have to do it numerically?
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Running window design for irregular or nonuniform time series

I have to deal with multiple time series $X_n$ that are non-uniformly or irregularly sampled at increasing times $\Theta=\{t_k\}_{k\in \mathbb{Z}}$ ($ t_k<t_{k+1}$). In case this could help, this ...
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Confusion understanding phase shift/delay?

I am reading proakis, as shown highlighted in attached snap shot,there is '-'sign along with j,but still it is written (underlined red) implies shift in positive n direction,why and how positive?when ...
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Determining SINAD from measured data

I would like to determine the SINAD of a distorted signal from a measurement and have troubles to get consistent data. The problem is (at least to my understanding) that I only have a very limited ...
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Why does Matlab spectrogram look stripy when windowed input is zero-padded?

I am working on a little project, and stumpled upon something I cannot understand yet. I am learning cognitive science, and don't have DSP knowledge background, only learning from what I find on the ...
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Periodogram/PSD from FFT amplitude

I have performed a STFT for signals and obtained the amplitude through ...
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FFT/PSD/IFFT analysis on single axis piezoelectric accelerometer signals for curb impacts

I'm trying to denoise the signal by performing PSD analysis and followed by IFFT. Ultimately, I want to generate Force and Displacement plots from the denoised acceleration signal. Noisy Acceleration ...
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Windowing of signal before FFT

I am facing an interesting problem: I have a signal in the time domain. In order to avoid discontinuities at the edges of the signal --- which would lead to artifacts when calculating the FFT --- I ...
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Blackman window magnitude attenuation

I am trying to compute the fundamental phasor using sliding window DFT. I have employed a Blackman window in conjunction i.e $$ \sum_{k=0}^{L_{DFT}-1}x(k) w(k) e^{-j2\pi k/N} $$ where $x(k)$ is the ...
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What's the ideal FFT window for measuring a group of signals of differing amplitudes but close in frequency?

In my system, I need to measure the amplitudes and phases of four lasers, each of a different, known wavelength, chopped at a 50% duty cycle via TTL at frequencies spaced evenly (or not) around some ...
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Find Magnitude of a DFT signal using a Blackman window

Hi I've been given a signal made of a series of cosines. I have taken the DFT of the signal using a rectangular window (blue), hamming window (red) and a Blackman window (black). I have identified two ...
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Understanding this Hanning Window implemented in microcontroller

I'm trying to calculate RMS of an AC signal which input frequency may vary from 40 to 70 Hz. I would like to use a window function because it accounts for frequency variations and also my ADC sampling ...
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Coherent Sampling vs Windowing for 50/60 applications

Let's say I need to sample 50/60 Hz signals to find RMS. I can use for example 1kHz sampling frequency. That means 100ms sampling is 5 cycles of 50Hz and 6 cycles for 60 Hz. That's coherent sampling. ...
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window function between program and math

I'm newbie on signal processing. I know when we program python with window function. (just signal multiply with window) According to Harris paper I know we change w with different window(blackman). ...
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Is the DCT prone to spectral leakage like the DFT?

My understanding is that the DCT assumes the input to be an even periodic signal. This avoids the discontinuity that can occur in the periodic extension assumed by the DFT (see image). Does this lack ...
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Estimate Parameters of Linear Combination of Harmonic Signals with Partial Known Frequencies

Consider real signal of the form: $$ \begin{align*} x(n) = &\sum_{m=1}^{M} \left( c_m \cos(2\pi f_m n) + s_m \sin(2\pi f_m n) \right) =\\ &\sum_{m=1}^{M} a_m \cos(2\pi f_m n + \phi_m) \end{...
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Variable Window Size of Blackman FIR filter

I am trying to implement an FIR filter with a Blackman window function. The solution I got for my signal filtering problem is to have different window sizes for certain characteristics of the input ...
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Frequency Support of Window Functions

All window functions, which go from zero amplitude, up, then back to zero amplitude, are all base-band signals. Why is this? Are all functions that have this behavior always band-band aka low-pass?
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Zero Meaning a Hamming Window in Matlab

I am still relatively new to signal processing and MATLAB and am working on a short-time fourier transform of some data using a prexisting code. Within the code a Hamming window is produced and ...
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Reconstructing a signal from multiple filtered copies using overlapping tapered windows

I have an audio signal that I need to process and analyse in blocks. I've now decided to process it using overlapping non-symetric Hanning windows of length M = 9600 and a hopsize of R= M/2. I zero ...
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3 votes
2 answers
522 views

FFT result of windowed cosine function

The frequency spectrum of cosine function is as below. While adopting a square window function to the cosine function, it is same as implementing convolution of their frequency spectrum as below. The ...
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1 vote
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Why could window function help to get more accurate specific frequency amplitude?

In order to calculate amplitude of sinusoidal signal at a frequency around 60 Hz (but may be not 60 Hz), window function is adopted while using DFT. hk is the coefficient of window function and Kdc ...
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