AOA method using DW 1000 IC

Hello!
I have read one paper about AOA method with usage of DW1000 IC and I would like to know which way we can get synchronization frame delimiter (SFD) of angles A and B. (It’s presented in part F (AOA method calculation) of second section (Theoretical background) of paper).
The link to this paper:https://www.researchgate.net/publication/322408155_Angle_of_arrival_estimation_using_decawave_DW1000_integrated_circuits
Thanks in advance