Hi ! I am using a USRP 2952R. I am trying to send PSK and QAM modulated signals. The received EVM never goes below 4% and the clouds in the constellation diagram stay very high. I am just using the examples from the modualtion toolkit. TX1 and RX2 are connected by wire and a -30 attentuator (so the RX is not damaged).
Has anyone also tried these examples? What are your performances? On the hardware diagram I see that the PLL-loop is not common for both, can this be the problem? How to solve this?
When sending 4QAM (where the I and Q absolute amplitudes should be the same everywhere) I can clearly see thet most of the time one of the components is almost half of the other one.
