i am trying with AD6655 FFT. the testing is as below.
NCO HB↓2 FIR fADC/8 NCO with real output.
the sampling clock is 122.88MHz, FIN=152.824MHz, NCO=153.624MHz
the signal is 14.56MHz; while there is a spur at 16.113MHz.
it seems that 152.824-153.624=-0.8MHz，fADC/8=15.36MHz，then -0.8+15.36=14.56MHz
16.113MHz ( about 16.16MHz ) is generated by fADC/8 NCO.
i am not sure whether it is right or not.