encoding NRZ polar as square wave ?

Hello I have tried to encode my binary information over specific interval in time

fb= 1e3;                    % the channel date rate 
Tb=1/fb;                    % the bit period or bit interval
fs=16*fb;                    %Sampling frequency 
Ts=1/fs;
a=[0 1 0 1 1 0 1 1 0 0 0 1]
t=0:Ts:Tb*length(a)-Ts;
i=1;
%nrzData
for j = 1:length(t) 
    if t(j)<=i
        y(j)=a(i); 
    else
        y(j)=a(i); 
        i=i+1; 
    end 
end

I have got all them as -1 , even if I have try a_e=[-1 1 -1 1 1 -1 1 1 -1 -1 -1 1] instead of a.

Could you please help to generate the encoding array ?

Answer 1

[KALYAN ACHARJYA]

Note: This same can be easily done without using for loop (recomended), but first try to understand the issue, where you did wrong.

have got all them as -1 , even if I have try a_e=[-1 1 -1 1 1 -1 1 1 -1 -1 -1 1] instead of a.

Yes, see you have defined

i=1;

Evertime you just exucating the following only

y(j)=a(i); 
%Whaever j value, i value is 1 alwayas so y(j)=a(1) so its gives -1 everywhere

Every irerations you used the same i, as a(1)

for j = 1:length(t) 
    if t(j)<=i
        y(j)=a(i); 
    else
        y(j)=a(i); 
        i=i+1; 
    end 
end 

Always if coldition is true (all elements of t ovectors are less than 1), there is no i increment, as i increment assgnment inside the else condition part.

Wayout: Make the i=i+1 outside the if elase condition

for j = 1:length(t) 
    if t(j)<=i
        .....
    else
       ....
    end 
i=i+1; 
end 

Second Probable Error after considering i outside the if else condition:

Index exceeds matrix dimensions.
        y(j)=a(i);

In for loop j having length

>> length(j)

ans =

   192 

When i pass through 192 ierated, it aslo incremented to 192, but as "a" length is 12 only therefore it shows error, when j length more than 12.

as you assigned y value as a(j)

therefore a(1) data avaliable

a(2)...data avaliable

.....

a(12) data avaliable

..after a(13) data not avaliable as you defines as as a_e

   a=[-1 1 -1 1 1 -1 1 1 -1 -1 -1 1]  

If any isuue let me know here.

Hope it helps!

[Willim]

Index exceeds matrix dimensions.

Error in Untitled15 (line 12)
        y(j)=a(i); 

[KALYAN ACHARJYA]

Yes you definitely get the error, because length of j is 192 and length of data (a) have 12 only

>> length(j)
ans =
   192   

To avoid this error in same loop, the length of j and length of data (a) must have same. Chose the length of t is such a way that it doesnt have more than a (For logic you have to check).

t=0:Ts:Tb*length(a)-Ts;

Please note that length of j is same as length of t.

[Willim]

Thank you I have generate a different code that works for me

[KALYAN ACHARJYA]

Welcome !