47 C.F.R. § 80.377
Frequencies for ship earth stations
The frequency band 1626.5-1645.5 MHz is assignable for communication operations and radiodetermination and telecommand messages that are associated with the position, orientation and operational functions of maritime satellite equipment. The frequency band 1645.5-1646.5 MHz is reserved for use in the Global Maritime Distress and Safety System (GMDSS).