For our 64-Qam custom waveform of 25Mhz and sampling rate of 30.72, tried to configure ad9361with same settings as "LTE 20 MHz waveform" settings, which is;
Tx and Rx FIR filter with interpolation factor = 2.
Tx Chain: HB1,HB2 with interpolation factor of 2, HB3 interpolation factor of 1(bypassed).
RX Chain : HB1,HB2 and HB3 interpolation factor of 2 each.
With these settings constellation plot at the receiver, for some cases is coming clean, but other times it is scattering too much, as shown in the figures attached. Transmission is done over an RF cable with negligible loss.
Are these settings mentioned above are correct or they can be changed and improved for given BW and sampling rate.
Please help. Thanks.