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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

Here is the chain sanity test result:

TX:

https://www.alteraforum.com/forum/attachment.php?attachmentid=10474

RX:

https://www.alteraforum.com/forum/attachment.php?attachmentid=10475

I believe the chain passes the test. So, problem is in the loop. Well... to be honest I still doubt in the NCO

the problem in my point of view is in the nature of the NCO it self because as we discussed.. we are unable to control phase independently from

frequency... but your point about using loop filter every 10 samples stirred some hope in me. So, what's next?