The JANUS Underwater Communications Standard: From Promulgation to Present

JANUS is a NATO standard (STANAG 4748) [1] and is the first internationally adopted digital underwater acoustic communications standard. In a nutshell, it is a simple and robust modulation and coding scheme that can be easily adopted by a wide range of existing systems. JANUS has been developed by the NATO STO Centre for Maritime Research and Experimentation (CMRE), in collaboration with Academia and Industry, with the goal to break the interoperability barrier of digital underwater acoustic systems. JANUS technical specification is available without security markings from the NATO standardization Office (NSO). Therefore, it is open and free for use by military and civilian operators. As of 2024, JANUS is still the only open standard for digital underwater acoustic communications. This document describes the evolution of JANUS from its promulgation on March 24th 2017 to present. It covers some of the JANUS milestones regarding the engagement with the operational community and Industry, definition of applications and scenarios, at-sea experimentation, up to the most recent STANAG revision.