View source for Scilab/C4/Digital-Signal-Processing/English

'''Title of script''': '''Signal processing Using Scilab'''

'''Author: Manas'''

'''Keywords: Video tutorial, Signal'''



{| style="border-spacing:0;"
! <center>Visual Cue</center>
! <center>Narration</center>

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 1
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Dear Friends,

Welcome to the spoken tutorial on “'''Signal Processing using Scilab'''”

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 2 -Learning Objective Slide
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| In this tutorial, using Scilab, I will show you how to


Generate different kinds of signals , and


Perform different operations to analyse signals.

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 3-System Requirement slide
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| To record this tutorial, I am using '''Ubuntu 11.04''' as the operating system with '''Scilab 5.3.3''' version 

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 4- Prerequisite slide
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Before practicing this tutorial, a learner should have a basic knowledge of Scilab. 

To know the basics of Scilab, please refer to the series of basic level spoken tutorials in Scilab....


....which is available on our website www.spoken-tutorial.org

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 7
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| In this tutorial, I will describe about 3 basic Signals.

* Plotting continuous and discrete sine wave.
* Plotting '''step function'''.
* Plotting '''ramp function'''.

Let me start with “Plotting continuous and discrete sine wave”

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Switch to the Scilab Console Window and type:

'''t <nowiki>=</nowiki> 0:0.1:2*%pi;'''

'''x <nowiki>=</nowiki> sin(t);'''

'''plot2d(t,x)'''
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Let us switch to the Scilab Console Window.

Here type: 


'''t equal to zero colon zero point one colon two multiplied by precentage pi semicolon.'''

'''x equal to sin of t semicolon plot 2D into bracket t comma x'''


and press '''Enter''' key on your keyboard. 

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Display the plot generated
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| This is a '''continous sine wave'''




|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| On the console window type:

'''plot2d3('gnn',t,x)'''



| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Let us discuss the '''discrete sine wave.'''


On the console window type: '''plot two d3 within bracket invertes comma gnn comma t comma x and press Enter.'''




|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Display the plot generated
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| This is '''discrete sine wave.'''

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Switch to Slide 7: and display 2<sup>nd</sup> and 3<sup>rd</sup> point of Slide 7
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Let us now discuss about Plotting '''step function''' and 

plotting '''ramp function.'''

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Open scilab editor.

Open the file signal.sce
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| I have already written the code to generate '''step''' and '''ramp''' signal in the file called '''signals.sce.''' 


Let us open this file '''signal.sce''' using '''scilab editor'''.


Let us execute this code.


Click on the “Execute” button in the Menu bar




|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Display the plot generated
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| '''Step''' and '''Ramp''' signal is displayed in this plot.

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 8
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Now let us learn how to perform different operations to analyse signals.


Let us see how to perform '''Convolution''' between two signals.

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Swtich to Scilab console and type: '''<nowiki>x=[1,2</nowiki> ,3,4]'''

'''Then type:'''

'''<nowiki>h=[1,1,1]</nowiki>'''

'''and then type'''


Type:''' convol(x,h) '''and press Enter



| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Let us switch to the Scilab Console window and type

'''x equals to within square braccket one comma two comma three comma four'''




Then type '''h equals to within square bracket one comma one comma one'''


Now let us apply the '''convoltion''' by typing''' convol opening bracket x comma h closing bracket'''


and press Enter on your keyboard.




|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Display the output generated
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| An output can be seen here.

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| 
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Now let us learn '''Discrete fourier transform''' for a discrete sequence by using the inbuilt command '''dft().'''

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| On the Scilab console window, type: <nowiki>x=[1,2,3,4]</nowiki>


Type: '''<nowiki>[xf]=dft(x,-1);</nowiki>'''
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| On the console window here type '''x equals to within square bracket one comma two comma three comma four'''


Then


Type''' within square bracket xf equals to dft into bracket x comma minus 1'''


Where x is the input vector 


and flag value is -1 for DFT.


Let us press Enter




|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Display the output:


'''10. '''

'''- 2. + 2.i '''

'''- 2. - 9.797D-16i '''

'''- 2. - 2.i '''
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| The output appears as this


'''10. '''

'''- 2. + 2.i '''

'''- 2. - 9.797D-16i '''

'''- 2. - 2.i '''

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| 
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Now I will show you how to calculate inverse discrete '''fourier transform'''. This can be done by using the same inbuilt command '''dft().'''

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| On the Scilab console window:'''<nowiki>[x]=dft(xf,1)</nowiki>''' 
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| On the Scilab console window type: 

'''squareBracket x equals to dft within bracket xf comma 1'''


Here the '''flag value''' is 1 for '''idft.'''

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Display the output: '''1. '''

'''2. + 5.551D-17i '''

'''3. - 1.225D-16i '''

'''4. - 5.551D-16i'''
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| This is the output.

'''1. '''

'''2. + 5.551D-17i '''

'''3. - 1.225D-16i '''

'''4. - 5.551D-16i'''




|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| 
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Let us calculate discrete fourier transform using '''fft()'''

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Type: x= <nowiki>[1,2,3,4]</nowiki> and press Enter

Type:'''y <nowiki>=</nowiki> fft(x,-1)'''


Display the output:

'''10. - 2. + 2.i - 2. - 2. - 2.i '''
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| On the console window, type '''x= <nowiki>square [1,2,3,4]</nowiki> x equals to square bracket one comma two comma three comma four'''

Press Enter and type '''y <nowiki>=</nowiki> fft(x,-1)''' y equals to fft within bracket x comma minus one

Press Enter and you can see the output as these:-


'''10. - 2. + 2.i - 2. - 2. - 2.i '''

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| On the Scilab Console window type: '''<nowiki>y=[10,-2+2*%i,-2,-2-2*%i]</nowiki>''' and press Enter


Type: '''x <nowiki>=</nowiki> fft(y,1)''' 


and Press Enter



| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Let us now see how to calculate inverse discrete fourier transform by using '''fft().'''


On the Scilab console window type

'''y equals to within square bracket ten comma minus two plus two into percentage i comma minus two comma minus two minus two into percentage i.'''


and Press Enter


Type '''x <nowiki>=</nowiki> fft(y,1)''' x equals to fft within bracket y comma 1


and Press Enter




|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Display the output:

'''x <nowiki>=1.</nowiki> 2. 3. 4.'''
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| The output will be displayed as 

'''x <nowiki>=1.</nowiki> 2. 3. 4.'''

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| 
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Let us now find out the correlation between two vectors.

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Switch to the Scilab console window


Type: '''<nowiki>x1=[1,2,3,4]</nowiki> '''and Press Enter


Type: '''<nowiki>x2=[1,3,1,5]</nowiki> '''and press Enter


Type '''Rx1x2 <nowiki>=</nowiki> corr(x1,x2,4)'''


The output will be displayed as

'''Rx1x2=1.25 0.3125 0.25 - 0.9375 '''
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| To do this on the Scilab console window, 


Type '''x one equals to within square bracket one comma two comma three comma four'''and press Enter


Type''' x2 equals to within square braccket one comma three comma one comma five '''and press Enter


Type '''R x one x two equals to corr within bracket x one comma x two comma four '''and press Enter


The output will be displayed as

'''Rx1x2=1.25 0.3125 0.25 - 0.9375''' 

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| 
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Let us learn how to sample the given signal

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Open sampling.sce


Click on “Execute” button


Display the output.
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Let me open sampling.sce where

I have already written the code in sampling.sce


Here click on the “'''Execute'''”button.


A plot is displayed.




|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| 
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Let us summarise.

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Slide 14
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| In this tutorial we have learnt

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Display Summary slide
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| How to Plot sine, step and ramp signal.


To perform Linear convolution by convol().


To perform DFT and IDFT by dft().


To perform FFT by fft().


To find out the Correlation by corr().


To do sampling

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Display “About the Spoken Tutorial Project” Slide
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Watch the video available at


this URL http://spoken-tutorial.org


/What is a Spoken Tutorial


It summarises the Spoken Tutorial


project


If you do not have good


bandwidth, you can also download


and watch it




|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Display “ Spoken Tutorial Workshops” slide
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| The Spoken Tutorial Project Team


Conducts workshops using spoken


tutorials


Gives certificates to those who


pass an online test


Please contact us


contact@spoken-tutorial.org




|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Display “Acknowledgment”

slide
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Spoken Tutorial Project is a part


of the Talk to a Teacher project


It is supported by the National


Mission on Education through


ICT, MHRD, Government of India


More information on the same is


available at:


http://spoken-tutorial.org


/NMEICT-Intro




|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Disaplay “Contributors” slide
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| This script has been contributed


by Manas and this is Sheetal Prabhu


signing off


Thank you for watching




|}