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[FMCOMMS3/ZedBoard] Tuning tx/rx properly GNU Radio

Question asked by vshn on Mar 10, 2016
Latest reply on Mar 17, 2016 by vshn

Hey,

 

This is a follow up to a previous post. I am having issues implementing a working (in all s/w) qpsk modulation scheme with the SDR devices. When running these two GRC flows (rx and tx) there are no errors received (sampling/attenuation). When viewing the scope output on the RX end arbitrary bit values are being read. This must be a tuning issue because there doesn't seem to be a difference viewed regardless if the transmitter is on or off.

 

I have successfully transmitted using an FM modulation scheme at the same carrier frequency.

 

It is expected to view both channels (I/Q) alternating between 1 and 0. Please see the attached diagrams and iio_info outputs. I'm really not sure what's going wrong here.

 

QPSK TX/RX and all SW flows

 

QPSK Receiver IIO_INFO

 

QPSK Transmitter IIO_INFO

 

Any ideas as to why this is not working in hardware?

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