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I see... but that's all for MATLAB, and I'm afraid I won't have time to deploy it to FPGA! Since I am aware of additional work in hardware domain!
I am reading an article from Matlab help about CORDIC-Based QPSK Carrier Synchronization. Do you recommend following it?
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what is the cordic computing? is'it a feedback loop based as well?
you may also try your first loop design and use proper qpsk system(as suggested above) instead of single tone and see if it behaves. directly observing constellations.