butter is not working

when ever i use butter and filter function to plot,nothing is shown in my output screen.Except butter code output all other outputs are shown

[Mathieu NOE]

hi

it would be more efficient it you woud share your code & data ...

tx

[Scott MacKenzie]

No output using butter? Try the code below. Do you get any output on your screen?

fc = 300;
fs = 1000;
[b,a] = butter(6,fc/(fs/2));
freqz(b,a)

But, really, how do you expect a helpful answer given the absence of detail in your question. As @Mathieu NOE notes, post your code and data.

[MICHKEL ANGLO J]

@Scott MacKenzie i used that code also no output for me.

here is my code:

clc;

clear all;

close all;

m=1;

Am=5;

Fa=2000

ta=1/Fa;

t=0:ta/999:6*ta;

ym=Am*sin(2*pi*Fa*t);

subplot(4,1,1);

plot(t,ym);

title('message signal')

SNR=1

Ac=5

Fc=Fa*10;

tc=1/Fc

yc=Ac*sin(2*pi*Fc*t);

subplot(4,1,2);

plot(t,yc);

grid on;

title('carrier signal')

y=Ac.*(1+m*sin(2*pi*Fa*t)).*sin(2*pi*Fc*t);

subplot(4,1,3);

plot(t,y)

grid on;

title('Amplitude modulation');

s1=y.*yc;

[b,a]=butter(4,0.004);

s2=filter(b,a,s1);

subplot(4,1,4);

plot(s2);

grid on;

title('am demod');

below my code execution.i don'y get by 4th graph

[MICHKEL ANGLO J]

@Mathieu NOE i posted the code

[Scott MacKenzie]

I ran your code and I get a subplot with four graphs. Apparently you are not getting the 4th graph. Please post the output graph you are getting.

[MICHKEL ANGLO J]

@Scott MacKenzie here is the graph i got

[Scott MacKenzie]

Hmm, that's wierd. What version of MATLAB are you running?

What about plotting something simple in subplot(4,1,4) -- just to narrow down the problem. Try commenting out lines 29-35 in your code (as posted above) and inserting...

subplot(4,1,4);
bar(rand(3));

Here's what I get:

[Chunru]

Are you sure you are running the same code as you posted? Can you step through the code in debug mode?

[MICHKEL ANGLO J]

@Chunru a just copy and paste code.so there is no change not only this program ,butter function is not working anyother program.

@Scott MacKenzie no sir i can't use bar charts because i want to prove 1st and 4th graph as equal.

[Scott MacKenzie]

I'm only asking you to do this (create a bar chart in position 4) for debugging.

[MICHKEL ANGLO J]

ok i will do.

[Chunru]

Try "which butter" or "dbstop in butter".

Answer 1

[Chunru]

clc;
clear all;
close all;

m=1;
Am=5;
Fa=2000

Fa = 2000

ta=1/Fa;
t=0:ta/999:6*ta;
ym=Am*sin(2*pi*Fa*t);
subplot(4,1,1);
plot(t,ym);
title('message signal')

SNR=1

SNR = 1

Ac=5

Ac = 5

Fc=Fa*10;
tc=1/Fc

tc = 5.0000e-05

yc=Ac*sin(2*pi*Fc*t);
subplot(4,1,2);
plot(t,yc);
grid on;
title('carrier signal')
y=Ac.*(1+m*sin(2*pi*Fa*t)).*sin(2*pi*Fc*t);

subplot(4,1,3);
plot(t,y)
grid on;
title('Amplitude modulation');

s1=y.*yc;
[b,a]=butter(4,0.004);
s2=filter(b,a,s1);

subplot(4,1,4);
plot(s2);
grid on;
title('am demod');