I am confused in following question.
When I use the reference design provided by ADI in github I get the no-OS platform for AD9361, and I set the dds_data_select equal to DATA_SEL_DDS for all transmit channels. I get the wave at TX1A as follows,
then I zoom in the wave (tx_lo_freq = 2.4Ghz), which is shown in following,
now I chang tx_lo_freq equal to 500MHz, the wave is distorted.
and I make tx_lo_freq equal to 5GHz, the wave is shown following,
The baseband signal is not changed, and I only change tx_lo_freq, also I find there is no filter afer ATTN in blue block diagram. What reasons caused the distorted wave?