Random pulse generator

Hello,

I'm new in Simulink and i trying to make a pulse random generator. Pulses have amplitude (+10 & -10) and width (1 ms). The signal has to be non periodic, i mean, pulses has to appear by a random series. how can i do it? I apprecitate any help. The begining of my project depend of this signal.

Thanks. Néstor.

[Azzi Abdelmalek]

What is the maximale distance between two impulses?

[Néstor Monedero]

Hi Azzi, The maximale distance between two impulses may be 2 ms, for example. The idea is that: the distance is as close as possible. I achieve to do this pulse random generator with these blocks: A uniform random number, a matlab function that convert this pulses in other with amplitude +1/-1.

If you need more information, please, give me question. Néstor

[Azzi Abdelmalek]

Check the second image (modified)

set the Amplitude of the pulse generator to 2 and substract 1

Answer 1

[Azzi Abdelmalek]

use this block

the function is

function y = fcn(u)
%#codegen
id=rand(1)
if id>0.5 & u==0
  y=1
else
  y=0
end

or easier

%

Answer 2

[Fangjun Jiang]

Go to Simulink Sources library, there is the Random Number block and the Uniform Random Number block.

The output of the Uniform Random Number is between 0 and 1, so you'll need to use Relational Operator block to compare it with constant such as 0.1 and 0.9, and then use Switch block to output the +10 or -10 or 0 pulse value.

[Néstor Monedero]

Hi, yes i can use both, but, how can i control the width of pulses?

I need a signal of pulses of the same width (1ms) and pulses has to appear randomly on time.

Thanks.

[Fangjun Jiang]

You can compare the random number with a constant, e.g. 0.9 and then add a zero-order holder block.

[Fangjun Jiang]

See update.

Answer 3

[Néstor Monedero]

I try to simulate random pulse generator using "uniform random number" plus a Matlab function. The code of the Matlab function is:

function y = fcn(u)
   %#codegen
   n=length(u);
   y=[1:n];
   for i=1:n
     if(u(i)<-0.9)
         y(i)=-1;
     end
     if(u(i)>0.9)
         y(i)=1;
     else
         y(i)=0;
     end
   end

The result is not what i want. I only obtain pulses with positive amplitude. I need two kind of pulses: positive and negative. what i am doing wrong? any idea? Please i need to build this signal to advanced in my project. Thanks in advance. Néstor.

[sneha j]

hi, there is a bug in ur code.

In the case that u(i)<-0.9, y(i) sets to -1 in the first if-block.

But wen it executes the 2nd if-block - if gets overwritten by y(i)=0 as u(i)<0.9, so it executes the else part of the block.

U need to club the the first if block with the 2nd if-else block into one if block as follows:

if(u(i)<-0.9)
    y(i)=-1;
else if(u(i)>0.9)
    y(i)=1;
else
    y(i)=0;
end

Hope it works well.

[sneha j]

hi Nestor, sorry i jus realised that the else if block doesnt work, so here is a workaround:

if(u<-0.5)
    y=-10;
else
    y=0;
end
if(u>0.5)
    y=10;
end