Implementation of Decimation Process 

AIM: To implementation of decimation of given sequence by factor M.  

EQUIPMENTS:  

Operating System - Windows XP

Constructor - Simulator

Software - CCStudio 3 & MATLAB 7.5

PROGRAM:

Clc;

Close all;

Clear all;

N=input(‘ input length of the sine seq’);

M= input(‘ down sampling factor’);

fi= input(‘ input signal freq’);  % generation of sine sequence  

t=0:N-1;

L=input(‘ enter the factor value’);

m=0:N*L-1;

x=sin(2*pi*fi*m);

%generate the down sample signal

Y=x([1:m:length(x)]);

Y([1:L:length(x)])=x;

Subplot(2,1,1);

Stem(n,x(1:N));

Title(‘ input sequence’);

Xlable(‘time’);

Ylabel(‘amplitude’);

Subplot(2,1,2);

Stem(n, Y);

Title([‘ output sequence ‘,num2str(m)]);

Xlable(‘time’);

Ylabel(‘amplitude’);

RESULT:  The decimator for a given sequence  is observed for chosen factor M.  

   Hence the theory and practical is verified.

VIVA QUESTIONS:

1.  What is the importance of decimation for a given signal/sequence?
2.  What do you mean Aliasing? What is the condition to avoid aliasing for sampling?
3.  How does poly phase  filtering save computations in a decimation filter?
4.  Give any practical application of decimation?
5.  Which signals can be down sampled?
6.  What happens if I violate the Nyquist criteria in down sampling or decimating?
7.  Can we do decimate in multiple stages?
8.  What are "decimation" and "downsampling"?
9.  What is the "decimation factor"?