creating user defined blocks

hi friends,
    i am doing my project on transmultiplexers.i want to do it in 
simulink.i am trying to create blocks for each one like 
decimator,interpolator.............
         but i always get an error .the following is the 
interpolation program.can anyone tell me how to create a block for 
this in simulink
clf;
dt=0.00005;
t=-0:dt:N-1;
N=input('input length:');
L=input('up-sampling factor:');
f0=input('input signal frequency:');
t=0:50;
n=0:N-1;
xa=sin(2*pi*f0*t);
x=sin(2*pi*f0*n);
y=zeros(1,L*length(x));
y([1:L:length(y)])=x;
subplot(2,1,1);
plot(t,xa);
hold on
stem(n,x);
title('input sequence');
xlabel('time index n');
ylabel('amplitude');
subplot(2,1,2);
stem(n,y(1:length(x)));
title(['output sequence up-sampled by',num2str(L)]);
xlabel('time index n');
ylabel('amplitude');
          thank you.
	

> Not sure what you really want, but this appears to just insert
> zero samples to up-sample the input. Simulink's DSP Blockset
> has the Upsample block in the Signal Operations section of the
> DSP Blockset library, which would do the same, I think.

If increased sampling rate is actually the desired result, don't forget to apply anti-aliasing filter after inserting zeros.  The filter should be LPF with cut-off at 1/2 original sampling rate.  Otherwise the 'edges' between samples and zeros contain frequencies higher than that.

-Jeff
 

 

---

From: m...@yahoogroups.com [mailto:m...@yahoogroups.com] On Behalf Of krishna_31985
Sent: Tuesday, February 14, 2006 8:18 PM
To: m...@yahoogroups.com
Subject: [matlab] creating user defined blocks

hi friends,
    i am doing my project on transmultiplexers.i want to do it in
simulink.i am trying to create blocks for each one like
decimator,interpolator.............
         but i always get an error .the following is the
interpolation program.can anyone tell me how to create a block for
this in simulink
clf;
dt=0.00005;
t=-0:dt:N-1;
N=input('input length:');
L=input('up-sampling factor:');
f0=input('input signal frequency:');
t=0:50;
n=0:N-1;
xa=sin(2*pi*f0*t);
x=sin(2*pi*f0*n);
y=zeros(1,L*length(x));
y([1:L:length(y)])=x;
subplot(2,1,1);
plot(t,xa);
hold on
stem(n,x);
title('input sequence');
xlabel('time index n');
ylabel('amplitude');
subplot(2,1,2);
stem(n,y(1:length(x)));
title(['output sequence up-sampled by',num2str(L)]);
xlabel('time index n');
ylabel('amplitude');
          thank you.