Hello, I am blocked with a QPSK problem that I would like to share, and maybe you will find my mistake.
I have build a QPSK transciever based the gnuradio tutorial for a project. The Tx part is not done by myself modulation is already made, I just have to emit the signal. Here is the spec : Bitrate : 2Mbps Sym rate : 1 Mbps Symbol Oversampling ratio: 9 Hardware: USRP b200mini The data send are two symbol, exactly 0x22 or 00 10 00 10 repeatly The reception use a LimeSDR. This part receive de signal but I can clearly see the the lock on is not working. I post some image of my flograph: Flowgraph: https://ibb.co/fJQxSo Data sent: https://ibb.co/mLJvDT Data received: https://ibb.co/dLNcSo My questions are: - How can I correctly lock the rotation? Playing with the “loop bandwidth does not really affect it”. - I feel like my sample rate are wrong, when I see the “received data”, it is like the point moving constantly on the circle of the phase and then shift the signal slowly and at the end I lost the good lock of my constellation. Is it possible? Thanks in advance and it needs more explaination, let me know I will post it. Cheers Sam
_______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
