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Altera_Forum
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11 years ago

Costas Loop oscillates in ModelSim while locks in MATLAB!

Hello again, I have designed a Costas Loop in MATLAB and it simulates very well... locking and recovering the carrier. Here are the results: http://www.alteraforum.com/forum/attachment.php?...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
11 years ago

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In fact you should get same patterns as your input stream. A high mean +1 and low means -1 (if nco are in phase). So don't worry about constellation diagrams.

In matlab if y is complex then plot(y,'.') will do.

for bpsk plot(I,Q*0,'.');

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I know how to plot them in matlab... in modelsim, as you mentioned I should see same patterns as in tx... and this is what I sent in tx.

What do we conclude now? Problem in loop?