File:Spectral leakage from two 8-point Poisson windows.png
Spectral_leakage_from_two_8-point_Poisson_windows.png (742 × 424 pixels, file size: 49 KB, MIME type: image/png)
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Summary
[edit]DescriptionSpectral leakage from two 8-point Poisson windows.png |
English: Comparing the discrete-time Fourier transforms of "symmetric" and "periodic" windows. The Poisson form was chosen for its non-zero end-points, one of which is discarded in the periodic version, with a noticeable performance degradation. |
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Date | ||||
Source | Own work | |||
Author | Bob K | |||
Permission (Reusing this file) |
I, the copyright holder of this work, hereby publish it under the following license:
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PNG development InfoField | N This PNG graphic was created with GNU Octave. |
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Octave/Gnuplot source InfoField | click to expand
This graphic was created with the help of the following Octave script: graphics_toolkit gnuplot
pkg load signal
N = 8;
symmetric = exp(-abs(((0:N-1) - (N-1)/2))*2/N); % 8-point Poisson window
periodic = exp(-abs(((0:N-1) - N/2))*2/(N+1)); % 8-points of a 9-point window
L=64*N;
dr = 60;
H = abs(fft([symmetric zeros(1,L-N)]));
H = fftshift(H);
H = H/max(H);
H = 20*log10(H);
H = max(-dr,H);
x = N*[-L/2:L/2-1]/L;
figure
plot(x, H, 'color', 'blue', 'linewidth', 2)
hold on
ylim([-dr 0])
H = abs(fft([periodic zeros(1,L-N)]));
H = fftshift(H);
H = H/max(H);
H = 20*log10(H);
H = max(-dr,H);
plot(x, H, 'color', 'red', 'linewidth', 2);
set(gca,'XTick', -N/2:N/2-1)
grid on
ylabel('decibels')
xlabel('DFT bins')
text(-1.13, -36.6, '\leftarrow Symmetric', 'color', 'blue','FontSize', 14)
text(-2.1, -19, 'Periodic', 'color', 'red','FontSize', 14)
title('"Spectral leakage" from two 8-point Poisson windows','FontSize', 14)
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Date/Time | Thumbnail | Dimensions | User | Comment | |
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current | 22:43, 6 April 2016 | ![]() | 742 × 424 (49 KB) | Bob K (talk | contribs) | User created page with UploadWizard |
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PNG file comment |
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Horizontal resolution | 28.35 dpc |
Vertical resolution | 28.35 dpc |
File change date and time | 22:30, 6 April 2016 |