File:Sigma delta.png
Size of this preview: 800 × 560 pixels. Other resolutions: 320 × 224 pixels | 640 × 448 pixels | 1,024 × 717 pixels | 1,280 × 896 pixels | 1,500 × 1,050 pixels.
Original file (1,500 × 1,050 pixels, file size: 93 KB, MIME type: image/png)
File information
Structured data
Captions
File:Sigma-delta PWM.svg is a vector version of this file. It should be used in place of this PNG file when not inferior.
File:Sigma delta.png → File:Sigma-delta PWM.svg
For more information, see Help:SVG.
|
Summary
editDescriptionSigma delta.png | Main signals of a sigma-delta Pulse-Width Modulation (PWM) |
Date | |
Source | Own work |
Author | Cyril BUTTAY |
Permission (Reusing this file) |
as licenced |
Licensing
editI, the copyright holder of this work, hereby publish it under the following licenses:
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License.http://www.gnu.org/copyleft/fdl.htmlGFDLGNU Free Documentation Licensetruetrue |
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. | ||
| ||
This licensing tag was added to this file as part of the GFDL licensing update.http://creativecommons.org/licenses/by-sa/3.0/CC BY-SA 3.0Creative Commons Attribution-Share Alike 3.0truetrue |
This file is licensed under the Creative Commons Attribution-Share Alike 2.5 Generic, 2.0 Generic and 1.0 Generic license.
- You are free:
- to share – to copy, distribute and transmit the work
- to remix – to adapt the work
- Under the following conditions:
- attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
- share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.
You may select the license of your choice.
Details
editThis graph represents the main signals of a sigma-delta PWM. The top green waveform is the reference signal, on which the output signal (PWM, in the middle plot) is substracted to form the error signal (blue, in top plot). This error is integrated (bottom plot), and when the integral of the error exceeds the limits (red lines), the output changes state.
This plot was created with Gnuplot by n.
This figure was made using the following python code (requires gnuplot 4.0 and scipy):
#!/usr/bin/python #this file generates data and the gnuplot file used for the sigma # delta pwm plot. Needs python, scipy and gnuplot (4.0 used) from scipy import * freq= 0.05 # frequency of the reference signal step=1e-3 # calculation time step hysteresis=0.15 # hysteresis of the sigma-delta pwm pwm=[1] # This vector is the pwm signal grid=["0"] # this vector contains the x-values at which the pwm signal # changes state error=[0] integral=[0] file = open("sigma_delta.dat","w") # the data file for i in range(int(1/(freq*step))): reference=sin(i*step*freq*2*pi) error=reference-pwm[i] integral.append(integral[i]+step*error) if integral[i+1]>hysteresis: pwm.append(1) grid.append("%s"%(i*step)) elif integral[i+1]<-hysteresis: pwm.append(-1) grid.append("%s"%(i*step)) else: pwm.append(pwm[i]) file.write('%s\t%s\t%s\t%s\t%s\n'%(i*step,reference,pwm[i], error,integral[i])) file.close() # end of data generation xtics=',"" '.join(grid) # creates a string used for the x-tics file = open("sigma_delta.plt","w") # generates the gnuplot file file.write(""" # This file is used to generate a plot that explains the # principle of the sigma-delta pwm # graph configuration set terminal postscript eps enhanced "Times-Roman" 24 color solid set encoding iso_8859_15 unset title set line style 1 lt 3 lw 3 pt 0 ps 0 set line style 2 lt 2 lw 3 pt 0 ps 0 set line style 3 lt 8 lw 2 pt 0 ps 0 set line style 4 lt 4 lw 3 pt 0 ps 0 set border 15 lt 7 lw 4 set grid xtics ytics set xlabel "" set format x "" set bmargin 0 set tmargin 0 set ytics 1 set xtics (%s) set output "sigma_delta.eps" set multiplot set ylabel "Ref. and Error" set origin 0,0.695 set size 1,0.3 plot [0:19][-2.2:2.2] 'sigma_delta.dat' using 1:2 ls 2 title '' w l,\ '' using 1:4 ls 1 title '' w l set ylabel "PWM" set origin 0,0.395 plot [0:19][-1.2:1.2]'sigma_delta.dat' using 1:3 ls 4 title '' w l set arrow 1 from graph 0,first %s to graph 1, first %s nohead set arrow 2 from graph 0,first %s to graph 1, first %s nohead set ylabel "Integration" set xlabel "Time" set origin 0,0.095 plot [0:19][-0.25:0.25] 'sigma_delta.dat' using 1:5 ls 1 title '' w l unset multiplot """ %( xtics, hysteresis, hysteresis, -hysteresis, -hysteresis)) file.close() # end of the gnuplot file. #%set ytics ("0" 0, "-1" -1, "1" 1)
File history
Click on a date/time to view the file as it appeared at that time.
Date/Time | Thumbnail | Dimensions | User | Comment | |
---|---|---|---|---|---|
current | 20:41, 6 June 2006 | 1,500 × 1,050 (93 KB) | CyrilB~commonswiki (talk | contribs) | {{Information |Description=Main signals of a sigma-delta Pulse-Width Modulation (PWM) |Source=Own Work |Date=6/6/2006 |Author=Cyril BUTTAY |Permission=as licenced |other_versions= }} |
You cannot overwrite this file.
File usage on Commons
The following 3 pages use this file: