File:Pwm.gif
From Wikimedia Commons, the free media repository
Jump to navigation
Jump to search
Pwm.gif (640 × 480 pixels, file size: 268 KB, MIME type: image/gif, looped, 44 frames, 11 s)
File information
Structured data
Captions
Summary
[edit]DescriptionPwm.gif | de:Pulsweiten-Modulation |
Source | Own work |
Author | Mik81 |
% GNU Octave / MATLAB
% Benutzer:mik81 @ de.wikipedia.org
%
%
% Große Frage:
% Welche "amplitude" haben die Spektren?
%
%
printf("mik81 @ de.wikipedia.org\n\n");
printf("Spectrum of rectengular waveform\n\n");
stepsPerPeriod = 128; % 2^8
periods = 16; % 2^4
steps = periods*stepsPerPeriod;
timebase = 0:1:steps-1;
size(timebase)
% dutycycle = 0.05;
mkdir("./data");
axis("labelxy", "ticxy", "on");
for count=1:1:40
countString = sprintf("%03i", count);
dutycycle = count/80;
dutycycleString = sprintf("%0.3f", dutycycle);
realDutycycle = 0;
%
% set up waveform
%
printf("Calculating waveform: %i\n", count);
for period=0:1:periods-1
for step=0:1:stepsPerPeriod-1
if ( step >= dutycycle *stepsPerPeriod)
square = [square, 0.];
if ( realDutycycle == 0)
realDutycycle = step/stepsPerPeriod
dutycycle
endif
else
if (period == 0 && step == 0)
square = [+1.];
else
square = [square, +1.];
endif
endif
endfor
endfor
for step = 0:1:steps-1
if ( step == 0)
sinus = [sin(2*pi*0)];
else
sinus = [sinus, sin(2*pi*step/stepsPerPeriod)];
endif
endfor
sinus = 0:1:steps-1;
sinus = sin(2*pi*sinus/stepsPerPeriod);
% size(sinus)
% size(square)
plot((0:1:steps/(0.25*periods)-1)/stepsPerPeriod
, square(1,1:steps/(0.25*periods)), [";Tastgrad: " , dutycycleString, ";"]);
axis ([0, 0.25*periods, -0.2, +1.2]);
axis ("nolabel");
axis("labely", "ticxy");
xlabel ("");
__gnuplot_set__ size 0.42,0.42;
print(["./data/waveform", countString, ".png"], "-dpng");
__gnuplot_set__ size 1.,1.;
%
% DFT
%
printf("Calculating DFT: %i\n", count);
freqSteps = steps/2;
%
% Frequenz = freq*Samplerate*steps
% n * Fenster
% remove DC-part
%square = square .- sum(square(1,:));
for freq=0:1:freqSteps
pad = square .* sin(freq*2*pi*timebase/length(timebase));
dft(1, freq+1) = sum( pad(1,:) );
pad = square .* cos(freq*2*pi*timebase/length(timebase));
% cos^2 + sin^2
dft( 1, freq+1) = dft(1, freq+1)^2 + sum( pad(1,:) )^2;
% normalize = max(dft(1, freq+1), normalize);
pad = sinus .* sin(freq*2*pi*timebase/length(timebase));
dftSignal(1, freq+1) = sum( pad(1,:) );
pad = sinus .* cos(freq*2*pi*timebase/length(timebase));
% cos^2 + sin^2
dftSignal(1, freq+1) = dftSignal( 1, freq+1)^2 + sum( pad(1,:) )^2;
endfor
dft = sqrt(dft);
dft = dft/(periods*stepsPerPeriod);
dftSignal = dftSignal/(periods*stepsPerPeriod);
%envelop = dft(1,1) * abs(sinc((0:1/10:freqSteps)*dutycycle));
envelop = dft(1,1) * abs(sinc((0:1/10:freqSteps)*realDutycycle));
%size(dft)
%semilogx((0:1:steps-1)/stepsPerPeriod, square);
%semilogx((1:1:freqSteps-1)/periods, dft(2:freqSteps,1));
% plot
plot((0:1:freqSteps)/periods, dft(1, 1:freqSteps+1), ["+1;Spektallinien;"]
, (0:1:freqSteps)/periods, dft(1, 1:freqSteps+1), ["^1;;"]
, (0:1/10:freqSteps), envelop, ";Einhuellende;");
dftSelected = [dft(1,1)];
for selected=periods+1:periods:freqSteps+1
dftSelected = [dftSelected, dft(1,selected)];
endfor
%size(dftSelected)
%size([0, (periods+1:periods:freqSteps+1)/periods])
plot([0, (periods+1:periods:freqSteps+1)/periods-1/periods], dftSelected(1, :), ["+1;Spektallinien;"]
,[0, (periods+1:periods:freqSteps+1)/periods-1/periods], dftSelected(1, :), ["^1;;"]
, (0:1/10:freqSteps), envelop, ";Einhuellende;");
%semilogx((1:1:freqSteps-1)/periods, dftSignal(2:freqSteps,1));
%plot((1:1:freqSteps/8-1)/periods, dftSignal(2:freqSteps/8,1));
axis ([0, 20, 0, 0.6]);
axis("labelxy", "ticxy", "on");
xlabel ("Vielfache der Grundfrequenz");
%axis ("ticx");
print(["./data/spectrum", countString, ".png"], "-dpng");
%if ( freq == 8)
% fetch = pad;
% sum(pad(1,:))
% dft(1, freq+1)
% endif
%plot(0:1:length(fetch)-1, fetch, [";fetch", dutycycleString ,";"] );
%print(["./data/fetch", countString, ".png"], "-dpng");
endfor
Bash/ImageMagick
[edit]#! /bin/bash
echo "Script of mik81 @ de.wikipedia.org"
#vor00() {
# let "${{#1}==2" && $1=0${{1}
# let "${{#1}==1" && $1=00${{1}
# let "${{#1}==0" && $1=000
# echo $1
#}
#echo (vor00 5))
((i=1))
((m=40))
rm ./data/*
octave ./pulsweite.m
while ((i<=m)); do
case $i in
??) composite -gravity East ./data/waveform0$i.png ./data/spectrum0$i.png ./data/composite0$i.png;;
?) composite -gravity East ./data/waveform00$i.png ./data/spectrum00$i.png ./data/composite00$i.png;;
*) break;;
esac
((i=$i+1))
done
((i=41))
((m=45))
while ((i<m)); do
#octave ./pulsweite.m
cp ./data/composite040.png ./data/composite0$i.png
((i=$i+1))
done
convert -delay 25 ./data/composite*.png ./pwm.gif
Licensing
[edit]I, the copyright holder of this work, hereby publish it under the following license:
This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication. | |
The person who associated a work with this deed has dedicated the work to the public domain by waiving all of their rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law. You can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission.
http://creativecommons.org/publicdomain/zero/1.0/deed.enCC0Creative Commons Zero, Public Domain Dedicationfalsefalse |
File history
Click on a date/time to view the file as it appeared at that time.
Date/Time | Thumbnail | Dimensions | User | Comment | |
---|---|---|---|---|---|
current | 14:16, 26 February 2008 | 640 × 480 (268 KB) | Mik81 (talk | contribs) | {{Information |Description= de:Pulsweiten-Modulation |Source=self-made |Date= |Author= Mik81 |Permission= |other_versions= }} == en:GNU Octave == <source lang="c"> % GNU Octave / MATLAB % Benutzer:mik81 @ de.wikipedia.org % % % |
You cannot overwrite this file.
File usage on Commons
The following page uses this file: