[Discuss-gnuradio] QAM Modulation-Demodulation in Loopback

Hello All,

I am using bladerf in loopback mode with a 20 dB attenuator.

I am trying to implement QAM modulation-demodulation and I have attached the flowgraph I am using.

The problem is I am not getting the demodulated data.

I have used the same flowgraph for DBPSK,DQPSK, etc.

Any idea why it is not working for QAM ?

Also the QAM demod block has a parameter phase bw. In PSK demod, Costas Loop is used, but costas loop cannot be used for QAM so how is phase synchronization done for QAM ?

Thanks for any advice.

Kartik