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Description

English: Comparison among frequency outputs

\left|Y_{i}\left(e^{j\omega }\right)\right|

of discrete-time low-pass filters

h_{1}\left(n\right)

,

h_{2}\left(n\right)

and

h_{3}\left(n\right)

, where

h_{i}\left(n\right)=r_{i}^{n}\quad n=0,\ldots ,N-1

with

{\begin{cases}r_{1}=0,8\\r_{2}=0,5\\r_{3}=0,2\end{cases}}

, with gate sequence

x\left(n\right)=u\left(n\right)-u\left(n-N\right)

as the input.

Italiano: Confronto tra le uscite in frequenza

\left|Y_{i}\left(e^{j\omega }\right)\right|

dei filtri passa-basso a tempo discreto

h_{1}\left(n\right)

,

h_{2}\left(n\right)

e

h_{3}\left(n\right)

, dove

h_{i}\left(n\right)=r_{i}^{n}\quad n=0,\ldots ,N-1

con

{\begin{cases}r_{1}=0,8\\r_{2}=0,5\\r_{3}=0,2\end{cases}}

, con la sequenza porta

x\left(n\right)=u\left(n\right)-u\left(n-N\right)

all'ingresso.

Date

23 September 2017

Source

Own work

Author

Luca Ghio

Permission
(Reusing this file)

I, the copyright holder of this work, release this work into the public domain. This applies worldwide.
In some countries this may not be legally possible; if so:
I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.

Category:Self-published work#Gate%20sequence%20discrete-time%20low-pass%20filter%20frequency%20output%20comparison.pdf Category:PD-self#Gate%20sequence%20discrete-time%20low-pass%20filter%20frequency%20output%20comparison.pdf

gnuplot source

click to expand

N=11;
n=[0:N-1];
x=ones(1,N);
r1=0.8;
r2=0.5;
r3=0.2;
h1=r1.^n;
h2=r2.^n;
h3=r3.^n;
figure
set (gca,'FontSize',14)
stem(n,x)
xlabel('n')
ylabel('x(n)')
axis([0 10 0 2])
grid on
figure
set (gca,'FontSize',14)
stem(n,h1)
xlabel('n')
ylabel('h_1(n)')
axis([0 10 0 1])
grid on
figure
set (gca,'FontSize',14)
stem(n,h2)
xlabel('n')
ylabel('h_2(n)')
axis([0 10 0 1])
grid on
figure
set (gca,'FontSize',14)
stem(n,h3)
xlabel('n')
ylabel('h_3(n)')
axis([0 10 0 1])
grid on

N=11;
n=[0:N-1];
x=ones(1,N);
r1=0.8;
r2=0.5;
r3=0.2;
k1=(1-r1)/(1-r1^N);
k2=(1-r2)/(1-r2^N);
k3=(1-r3)/(1-r3^N);
h1=k1*r1.^n;
h2=k2*r2.^n;
h3=k3*r3.^n;
%  figure
%  set (gca,'FontSize',14)
%  stem(n,x)
%  xlabel('n')
%  ylabel('x(n)')
%  axis([0 10 0 2])
%  grid on
%  figure
%  set (gca,'FontSize',14)
%  stem(n,h1)
%  xlabel('n')
%  ylabel('h_1(n)')
%  axis([0 10 0 1])
%  grid on
%  figure
%  set (gca,'FontSize',14)
%  stem(n,h2)
%  xlabel('n')
%  ylabel('h_2(n)')
%  axis([0 10 0 1])
%  grid on
%  figure
%  set (gca,'FontSize',14)
%  stem(n,h3)
%  xlabel('n')
%  ylabel('h_3(n)')
%  axis([0 10 0 1])
%  grid on

f=linspace(-0.5,0.5,1000);
H1=k1*(1-(r1*exp(-j*2*pi*f)).^N)./(1-r1*exp(-j*2*pi*f));
H2=k2*(1-(r2*exp(-j*2*pi*f)).^N)./(1-r2*exp(-j*2*pi*f));
H3=k3*(1-(r3*exp(-j*2*pi*f)).^N)./(1-r3*exp(-j*2*pi*f));
figure
set (gca,'FontSize',14)
plot(f,abs(H1))
hold on
plot(f,abs(H2),'r')
plot(f,abs(H3),'g')
xlabel('f')
ylabel('|H_i(e^{j\omega})|')
axis([-0.5 0.5 0 1.5])
grid on
legend('|H_1(e^{j\omega})|','|H_2(e^{j\omega})|', '|H_3(e^{j\omega})|')

N = 11;
X = (sin(pi*f*N) ./ sin(pi*f)) .* exp(-j*pi*f*(N-1));
figure
set (gca,'FontSize',14)
plot(f,abs(X))
xlabel('f')
ylabel('|X(e^{j\omega})|')
axis([-0.5 0.5 0 11])
grid on

Y1 = X .* H1;
Y2 = X .* H2;
Y3 = X .* H3;
figure
set (gca,'FontSize',14)
plot(f,abs(Y1))
hold on
plot(f,abs(Y2), 'r')
plot(f,abs(Y3), 'g')
xlabel('f')
ylabel('|Y_i(e^{j\omega})|')
axis([-0.5 0.5 0 11])
grid on
legend('|Y_1(e^{j\omega})|','|Y_2(e^{j\omega})|', '|Y_3(e^{j\omega})|')

N=11;
n=[0:N-1];
x=ones(1,N);
r1=0.8;
r2=0.5;
r3=0.2;
k1=(1-r1)/(1-r1^N);
k2=(1-r2)/(1-r2^N);
k3=(1-r3)/(1-r3^N);
h1=k1*r1.^n;
h2=k2*r2.^n;
h3=k3*r3.^n;
y1=conv(x,h1);
y2=conv(x,h2);
y3=conv(x,h3);
n=[0:length(y1)-1];
figure
set (gca,'FontSize',14)
stem(n,y1)
xlabel('n')
ylabel('y_1(n)')
axis([0 20 0 1.5])
grid on
figure
set (gca,'FontSize',14)
stem(n,y2)
xlabel('n')
ylabel('y_2(n)')
axis([0 20 0 1.5])
grid on
figure
set (gca,'FontSize',14)
stem(n,y3)
xlabel('n')
ylabel('y_3(n)')
axis([0 20 0 1.5])
grid on

Category:Images with Octave source code Category:Created with GNU Octave Category:DFT vs DCT

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File:Gate sequence discrete-time low-pass filter frequency output comparison.pdf