File:Processing gain comparison (Hann vs Blackman).gif
Processing_gain_comparison_(Hann_vs_Blackman).gif (647 × 518 pixels, file size: 16 KB, MIME type: image/gif)
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Summary
[edit]DescriptionProcessing gain comparison (Hann vs Blackman).gif |
English: This figure compares the processing gain of two window functions for sinusoidal inputs, with both minimum and maximum scalloping loss. |
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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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Other versions |
Derivative works of this file: |
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GIF development InfoField | This GIF graphic was created with LibreOffice. |
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Gnu Octave Script InfoField | This graphic was created with the help of the following script:
Octave codegraphics_toolkit gnuplot
N = 256; % sams_per_fft;
window1 = hann(N)'/sum(hann(N));
window2 = blackmanharris(N)/sum(blackmanharris(N));
%
Fs = N; % sams_per_sec;
HzPerBin = Fs/N;
F1 = -20.0*HzPerBin; % bin -20
F2 = +20.5*HzPerBin; % bin 20.5
%
L = 100000;
n = 1:L;
x = exp(j*2*pi*F1/Fs*n) + exp(j*2*pi*F2/Fs*n);
x = x + (randn(1,L) +j*randn(1,L))*1.4;
%
sams_per_offset = 0.75*N; % overlap = 25%
%
% number of samples available beyond just one FFT
excess_sams = length(x) - N;
%
j1 = floor( excess_sams / sams_per_offset );
sams_per_offset = floor( excess_sams / j1 );
num_ffts = 1 + j1;
%
% define the first block of data
samples = 1:N;
%
amplitude1 = zeros(1,N);
amplitude2 = zeros(1,N);
%
% Loop over all the available blocks
for j1 = 1 : num_ffts
amplitude1 = amplitude1 + abs(fft( x(samples) .* window1 ));
amplitude2 = amplitude2 + abs(fft( x(samples) .* window2 ));
samples = samples + sams_per_offset;
end
%
amplitude1 = 20*log10(fftshift(amplitude1/num_ffts));
amplitude2 = 20*log10(fftshift(amplitude2/num_ffts));
%
abscissa = -40:40;
figure
set(gca,'FontSize',8)
subplot(2,1,1);
h = area(abscissa, amplitude1(abscissa +N/2+1), ...
'FaceColor', [.871 .49 0], 'edgecolor', [.871 .49 0])
set(h,'BaseValue',-20)
xlim([-40 40])
ylim([-20 2])
set(gca,'XTick', [ ])
set(gca,'YGrid','on')
ylabel('decibels')
title('Hann');
%
subplot(2,1,2);
h = area(abscissa, amplitude2(abscissa +N/2+1), ...
'FaceColor', [.871 .49 0], 'edgecolor', [.871 .49 0])
set(h,'BaseValue',-20)
xlim([-40 40])
ylim([-20 2])
set(gca,'XTick', [ ])
set(gca,'YGrid','on')
ylabel('decibels')
title('Blackman-Harris');
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Date/Time | Thumbnail | Dimensions | User | Comment | |
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current | 01:02, 25 February 2013 | 647 × 518 (16 KB) | Bob K (talk | contribs) | User created page with UploadWizard |
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