# 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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### 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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### What is the spectrum of generalised periodic signals assuming mainlobe covers the first two harmonics?

I found this statement in the paper here which I have difficulty seeing why is it true. Let $H(\omega)$ represent the Fourier transform of a time-windowing function. Assume the width of the mainlobe ...
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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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### Deriving expression for the DTFT of a rectangular window

Looking at the picture above, how did the author get from point A) to B)? My Approach: Multiply A) by $e^{j\omega/2}/e^{j\omega/2}$. Now I am stuck with simplying the numerator.
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### LowPass Filter & Window *Img & Code* - Frequency Response has no lobe roll off

Not sure if I am doing something silly but I am not seeing lobe roll off on the frequency response of my windows and the low pass filter I made in MATLAB. Please can you help ... several hours just ...
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### High Order Filtering [duplicate]

Which window has better performance for higher order filtering? A. Rectangular window B. Hamming window C. Kaiser Window D. Hann Window Can anyone please answer this with explanation.
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### Fundamental component estimation

I am dealing with phasor estimation (fundamental component extraction primarily), and i am using sliding window DFT (which happens to be very popular for phasor estimation). Now at nominal frequency (...
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### Effect of changing sample rate, window duration and zero padding on DTFT and DFT

Let $T$ be the window duration, $N$ be the DFT size, $F_s$ be the sample rate, and $F_{max}$ be the frequency of the highest bin. In the context of image below: halving the $F_s$ (keeping $T$ ...
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### Smooth signal with Hanning

I have an acceleration record and i want to smooth it's spectrum by using a hanning window with Bandwidth=0.5 Hz. How could i do that? Example in python/matlab will be appreciated!
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### Hanning Window Bandwidth

I am using scipy's "scipy.signal.hanning" to determine a hanning window. This method returns an array with the window and specific number of points based on your input. More info: https://docs.scipy....
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### Confused in Smoothing a signal in the Frequency domain

First of all i am new in DSP, so i have no solid education in the field. I have convert my time domain acceleration-seismic data to frequency using DFT and i am trying to smooth the DFT data, in ...
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### Rectangular vs Hann windowing

I'm trying to create a basic digital signal processing pipeline, to manipulate a WAV file. Nothing fancy, I'm just looking to apply some filtering. My first attempt was to divide the input signal to ...
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### Harmonic Product Spectrum from FFT output to the fundamental frequency

I'm trying to do the HPS algorithm on my FFT output, but I'm stuck here. My signal is from a bass (cable), 16bits, 48.000Hz. I split in time domain the array of the whole record into multiple arrays ...
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### Using overlap add for drawing spectrogram

I'm confused with overlap-add (OLA) in the following two scenarios filtering/convolution an input signal; applying an STFT on input signal only and draw its spectrogram. When applying OLA to ...
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### Windowed N-point FFT

In the previous question, Smoothing in frequency domain and impulse reponse of the filter in time-domain I guess I have made a mistake in-terms for applying windowing to FFT. After reading "...
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### 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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### 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. ...
496 views

### windowed sinc filter in matlab

Hello i'm designing a low pass filter windowed sinc in matlab ...
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### Magnitude attenuation by a filter

I have a filter, with coefficients given by $$W=\sin((2*\pi*2*F_f*k/F_s)/(2*\pi*2*F_f*k/F_s))*h[k]$$, where $F_f$ is the filter reference frequency, $k$ runs from $-N/2$ to $N/2$ ($N$ is the order ...
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### 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 ...
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. ...