The European Union Agency for the Space Program (EUSPA), in collaboration with the European Commission, has published a new version of the Galileo Open Service Signal in Space Interface Control Document (OS SIS ICD).

The latest version, denoted v2.1, introduces new elements supporting the improvement and enlargement of the Galileo service portfolio. OS SIS ICD v2.1 is available along with a corresponding new version of the OS Service Definition Document (OS SDD).

New elements in v2.1 include the definition of OS Extended Operation Mode (EOM) and criteria for identifying when it is activated; description of a new ARAIM Integrity Support Message (ISM), and a new annex detailing a numerical example for the computation of its 32-bit checksum; and a new annex detailing the Galileo PRN Codes Assignment process, including codes belonging to the families E1 B, E1 C, E6 B, E6 C, E5a I, E5a Q, E5b I, E5b Q are now available.

Read more in GPS World article.