(eyediagram) Why I cannot get the eyediagram?

Question

Kwan Ho NG 2021-3-17

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/775667-eyediagram-why-i-cannot-get-the-eyediagram

评论： Kwan Ho NG 2021-3-17

clear;

M=2000

N=200;

temp= rand(1,M);

for i=1:M

if temp(i)>0.5

D(i)=1;

else

D(i)=-1;

end;

Ns=10; % Ns=5 or Ns=10

for i=1:M

for j=1:Ns

D_ext((i-1)*Ns+j)=D(i);

end;

h = firrcos(200,0.5,0.35,10, 'rolloff');%modify the parameter in different steps

out=conv(h,D_ext);

out_leng=length(out);

out_stable=(N+1:out_leng-N);

eyediagram(out_stable,20)

This is what I got.

This is the expected result.

2 个评论
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Cris LaPierre 2021-3-17

Consider pasting your code in rather than taking a screenshot. It's much easier to work with that way.

Kwan Ho NG 2021-3-17

编辑：Cris LaPierre 2021-3-17

在 MATLAB Online 中打开

clear;
M=2000
N=200;
temp= rand(1,M);
for i=1:M
    if temp(i)>0.5
        D(i)=1;
    else
        D(i)=-1;
    end;
end;
Ns=10; % Ns=5 or Ns=10
for i=1:M
    for j=1:Ns
        D_ext((i-1)*Ns+j)=D(i);
    end;
end;
h = firrcos(200,0.5,0.35,10, 'rolloff');%modify the parameter in different steps
out=conv(h,D_ext);
out_leng=length(out);
out_stable=(N+1:out_leng-N);
eyediagram(out_stable,20)

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Answer 1

Cris LaPierre 2021-3-17

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/775667-eyediagram-why-i-cannot-get-the-eyediagram#answer_650407

编辑：Cris LaPierre 2021-3-17

在 MATLAB Online 中打开

vars.mat

The issue appears to be with how you create out_stable. The result of this is a straight line. If you create an eyediagram using out instead, you see you are mostly there. You likley meant to trim the tails of out to clean up the eye diagram.

load vars.mat

h = firrcos(200,0.5,0.35,10, 'rolloff');%modify the parameter in different steps

out=conv(h,D_ext);

figure

plot(out)

figure

eyediagram(out,20)

out_leng=length(out);

out_stable=(N+1:out_leng-N);

figure

plot(out_stable)

eyediagram(out_stable,20)

That is likely due to the fact that out_stable is the index values of what you meant to keep from out. You forgot to tell the code to index these values from out. Try this instead.

figure

out_stable=out(N+1:out_leng-N);

% ^^^ Need to use your values as indices to out

eyediagram(out_stable,20)