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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46 views

How to determine number of filters in filter bank based on spectrogram of audio signal?

I want to do an analysis and than synthesis of audio signal, which is audio of vowel 'a', using Matlab. For this I need to use filter bank(array of band-pass filters). I have drawn four different ...
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54 views

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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43 views

FIR filter design using Kaiser window - passband ripple and stopband attenuation

I have been given the following parameters : lower cutoff frequency = $\pi/3$ lower cutoff freq = $2\pi/3$ beta = 5.6533 M = 51 Now I have to get magnitude and phase response of the filter using ...
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101 views

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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30 views

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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What is appropriate windowing technique for sine burst excitation?

I had to give sine burst to get good SNR. In above Blue color -> Actuation signal or input. Orange -> Response or output. I did use hanning window for both. The frf real & imaginary plot ...
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1answer
46 views

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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2answers
54 views

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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22 views

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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57 views

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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123 views

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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114 views

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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39 views

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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51 views

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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36 views

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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41 views

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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153 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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117 views

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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176 views

How to removed ripples cause by zero-padding in fft?

Desired outcome: Interpolation in frequency domain Attempts: Zero padding when doing fft Problem: Ripples in frequency domain appeared after fft with zero padding Code to reproduce the problem: ...
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72 views

Gibbs phenomenon, which window to use?

"Rectangular window" and "Triangular window" have gibbs phenomenon So which window should be used in fir filter design to have minimum or zero gibbs phenomenon
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1answer
89 views

Confusion calculating length of Kaiser window

I am reading Digital Signal Processing Using Matlab by Ingle and Proakis (3rd ed.) In Chapter 7, Section 7.3, I am confused why he is adding 1 to main lobe width for calculating length of window. I ...
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117 views

Compute Hann window without cos function

In an environment with limited memory and computing power it is interesting to be able to generate a Hann window without using a cache or repetitive calling of expensive functions such as sine and ...
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1answer
104 views

What is the difference of windowing functions for FIR filtering?

What is the difference of window types such as Hann, Rectangular, Hamming in the application. Is there such a thing that the one is better than the other? There will be an oral exam for DSP course ...
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240 views

WOLA vs Simple Hamming Window on signal before FFT

Im working on a project in which I should FFT a signal coming into my FPGA from ADC. I want my FFT to show the peak values as clear as possible without the side lobes. The solution should be straight ...
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51 views

Length of Hamming Window to Resolve a Harmonic

I am trying to answer the question: "Given a single-sourced pitch signal with a fundamental frequency of 440Hz and a sampling rate of 44100Hz how long should the Hamming window of the STFT analysis ...
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82 views

Blackman-Tukey Autopower equation

I am looking over Blackman-Tukey method for Autopower. It uses the DFT after a window is applied on a autocorrelation. $$ Power Spectrum = \frac1{2\pi} \ \sum_{(k=-(N-1))}^{N-1} w[k] R[k] e^{-i\...
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81 views

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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36 views

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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33 views

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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200 views

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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126 views

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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212 views

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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138 views

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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1answer
61 views

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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1answer
106 views

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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131 views

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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130 views

Smoothing in frequency domain and impulse reponse of the filter in time-domain

I have a low-pass signal in frequency domain, $$\left[f_{min}=0, f_{max}=20\,\mathrm{GHz}\right]_{n=100}$$ After re-configuring the input signal as $$X=\left[-f_{max},\ \dots\ -f_{min},\ \mathrm{DC},...
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274 views

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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3answers
142 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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46 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 ...
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1answer
48 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 ...
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144 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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55 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 ...
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1answer
155 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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45 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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111 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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195 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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1answer
687 views

windowed sinc filter in matlab

Hello i'm designing a low pass filter windowed sinc in matlab ...

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