Hello,
i was searching for good literature concerning the carrier recovery and PLL-functionalty for coherent QAM demodulation, but i could not find so much about that.
There is a small chapter about this in Xiong (Digital Modulation Techniques) about the 4th-power-loop and decision directed carrier recovery, but for my application in a homodyne optical receiver the 4th- power loop is not appropiate, and i want to prevent the use of a decision directed method.
Are there any other possibilities to realize the PLL for QAM? I heard that it is also possible to use the Costas Loop for QAM? Unfortunately i could not find anything about it.
Can anyone tell me where i can find information about this?
Thanks.
Matthias