SFD Phase Index

I’m trying to implement a PDOA system like the one described in the document Angle of Arrival Estimation Using Decawave DW1000 Integrated Circuits on page 3 paragraph F. There we would take the difference between the angle of the first path and the angle of the SFD. Now I would like to know how I can obtain the angle of the SFD? Is it in the CIR? And if yes, how do I get the proper index of it?