Systems & Technology Research (STR) proposes the development of a novel satellite constellation time transfer and synchronization architecture leveraging STRs extensive experience in the development of modeling and simulation environments, advanced algorithms, and experimental testbeds for precision metrology and RF applications. In this program we will focus on delivering sub-100 ps timing accuracy via satellite crosslinks for potential use as a GPS-surrogate in contested environments. The Phase I effort will focus on developing network algorithms for synchronizing an entire constellation of satellites informed by algorithms for individual time transfers, a comprehensive end-to-end modeling and simulation environment for individual time transfers, and a systems-level analysis of prospective constellations. Throughout the effort, STR will work to establish an advanced satellite constellation synchronization development plan for a Phase II demonstration using the fundamental approach developed during Phase I and the inclusion of feedback from the U.S. Government team to hone the research towards a direction that is amenable for a successful transition to the Air Force.time synchronization,time transfer,Satellite Constellation,Satellite Crosslink,Phase Errors,position,Navigation and Timing (PNT)