Just from very quickly over your attached images: Your receiver is clipping, you can see that: the receive waveform should never even touch "1".
You need to substantially reduce gain, potentially both in your receiver and transmitter. Best regards, Marcus On 08.06.21 16:32, Γιώργος Γιώργος wrote: > Hello to everyone on the list, > > To begin with, my overall goal is to build an adaptive modulation scheme > using GnuRadio > and USRPs. Concept-wise, this will be implemented by calculating the BER at > the receiver, > feeding this data to the transmitter, and switching between two different > modulation > schemes based on threshold BER values. > > I am currently working on an 8DPSK modulation format. After succesfully > building and > testing the flowchart in simulation, I split the transmit and receive chain > in order to > actually test the setup using two B210 USRPs. > > After a little bit of experimentation, transmission is great when using a > random source at > the transmitter. The FFT plot and the Constellation appear as expected. > However, when > using a vector source, which is mighty helpful for my purpose since I have a > known bit > sequence to compare at the receiver, my ouputs are unexpected (screenshots > attached). This > is baffling because the only thing that changed is the bit sequence and > nothing in the > actual signal processing chain (to be frank a packed to unpacked, and upacked > to packed > block were used after the vector source, but I'm getting pretty much the same > results > without them). I have experimented with different parameters but to no avail. > It is > important to note, that the simulations were working fine, regardless of the > source that > was used. > > Any thoughts on why this is happening? I have also attached screenshots of > the flowcharts. > > Thank you very much for all the effort you are putting into the project. > > Best regards, > George > >