What AD9361 receive chain settings yield the maximum SNR and SFDR without using any of the on-chip RX FIR filters?
I have experimented with the FMCOMMS3-EBZ board and I'm able to achieve 60+ dBc ACPR using a 5 MHz wideband signal without using any of the on-chip TX FIR filters when looking at the AD9361 transmitter output on a signal analyzer. However, when I loop this signal back to the AD9361 receiver input, I can't get the ACPR to be any better than the high 40's without using one of the on-chip RX FIR filters.
I've tried lots of combinations of automatic gain control, manual gain control, external amplification, and external attenuation, but, unless I use one of the on-chip RX FIR filters, I can't receive a signal of the same quality that I can transmit without using any on-chip TX FIR filters.
Is this expected?