Scilab/C4/Digital-Signal-Processing/English

Title of script: Signal processing Using Scilab

Author: Manas

Keywords: Video tutorial, Signal

Visual Cue	Narration
Slide 1	Dear Friends, Welcome to the spoken tutorial on “Signal Processing using Scilab”
Slide 2 -Learning Objective Slide	In this tutorial, using Scilab, I will show you how to Generate different kinds of signals , and Perform different operations to analyse signals.
Slide 3-System Requirement slide	To record this tutorial, I am using Ubuntu 11.04 as the operating system with Scilab 5.3.3 version
Slide 4- Prerequisite slide	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
Slide 7	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”
Switch to the Scilab Console Window and type: t = 0:0.1:2*%pi; x = sin(t); plot2d(t,x)	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.
Display the plot generated	This is a continous sine wave
On the console window type: plot2d3('gnn',t,x)	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.
Display the plot generated	This is discrete sine wave.
Switch to Slide 7: and display 2nd and 3rd point of Slide 7	Let us now discuss about Plotting step function and plotting ramp function.
Open scilab editor. Open the file signal.sce	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
Display the plot generated	Step and Ramp signal is displayed in this plot.
Slide 8	Now let us learn how to perform different operations to analyse signals. Let us see how to perform Convolution between two signals.
Swtich to Scilab console and type: x=[1,2 ,3,4] Then type: h=[1,1,1] and then type Type: convol(x,h) and press Enter	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.
Display the output generated	An output can be seen here.
	Now let us learn Discrete fourier transform for a discrete sequence by using the inbuilt command dft().
On the Scilab console window, type: x=[1,2,3,4] Type: [xf]=dft(x,-1);	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
Display the output: 10. - 2. + 2.i - 2. - 9.797D-16i - 2. - 2.i	The output appears as this 10. - 2. + 2.i - 2. - 9.797D-16i - 2. - 2.i
	Now I will show you how to calculate inverse discrete fourier transform. This can be done by using the same inbuilt command dft().
On the Scilab console window:[x]=dft(xf,1)	On the Scilab console window type: squareBracket x equals to dft within bracket xf comma 1 Here the flag value is 1 for idft.
Display the output: 1. 2. + 5.551D-17i 3. - 1.225D-16i 4. - 5.551D-16i	This is the output. 1. 2. + 5.551D-17i 3. - 1.225D-16i 4. - 5.551D-16i
	Let us calculate discrete fourier transform using fft()
Type: x= [1,2,3,4] and press Enter Type:y = fft(x,-1) Display the output: 10. - 2. + 2.i - 2. - 2. - 2.i	On the console window, type x= square [1,2,3,4] x equals to square bracket one comma two comma three comma four Press Enter and type y = 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
On the Scilab Console window type: y=[10,-2+2*%i,-2,-2-2*%i] and press Enter Type: x = fft(y,1) and Press Enter	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 = fft(y,1) x equals to fft within bracket y comma 1 and Press Enter
Display the output: x =1. 2. 3. 4.	The output will be displayed as x =1. 2. 3. 4.
	Let us now find out the correlation between two vectors.
Switch to the Scilab console window Type: x1=[1,2,3,4] and Press Enter Type: x2=[1,3,1,5] and press Enter Type Rx1x2 = corr(x1,x2,4) The output will be displayed as Rx1x2=1.25 0.3125 0.25 - 0.9375	To do this on the Scilab console window, Type x one equals to within square bracket one comma two comma three comma fourand 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
	Let us learn how to sample the given signal
Open sampling.sce Click on “Execute” button Display the output.	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.
	Let us summarise.
Slide 14	In this tutorial we have learnt
Display Summary slide	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
Display “About the Spoken Tutorial Project” Slide	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
Display “ Spoken Tutorial Workshops” slide	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
Display “Acknowledgment” slide	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
Disaplay “Contributors” slide	This script has been contributed by Manas and this is Sheetal Prabhu signing off Thank you for watching

Contributors and Content Editors

Gaurav, Lavitha Pereira, Nancyvarkey