as a fun project I am trying to build Quadrature Phase Shift Keying (QPSK) modulator & demodulator for a Digital Video Broadcasting (DVB) application. I am using the LimeSDR mini as my hardware and GNU radio as a starting point.
My first 'test case' is to just setup the QPSK signal to get passed through - straight from the sample source to the sample sink - but when I do that, garbage data is sent out the sink. A signal at the correct frequency is generated, but the data is not able to be demodulated by my test hardware.
I've been working with DVB for a while, but now just getting into the signal processing of it and Ive been having trouble.
Attached .grc and screenshot of my gnuradio blocks. Am I doing something wrong when setting up the passthrough section? What steps can I take to debug?