The methodology described in this portal might change, as the implementation of DFMC (Dual-Frequency Multi-Constellation) GBAS stations might require to adapt the present process. For example, the technical feasibility assessment should take into account the use of the GNSS double frequency signals in order to conclude the feasibility of implementing the system, and might change the procedures, people and resources needed in order to perform the task. 

Although still not in operation, research and development efforts are very active. For example, the EU project EDGAR (“EGNSS DFMC for GBAS based operations”) is explicitly working on the DFMC GBAS solution with GAST-E architecture.