Most recent development status of small-sized Ka-band mobile communications terminal is presented. The terminal is designed to operate at a minimum target speed of 5 Mbps to/from a Ka-band geostationary satellite, and will eventually be used for the purpose of research activity to explore marine resources within the Exclusive Economic Zone (EEZ) of Japan. The terminal is placed on Autonomous Surface Vehicle (ASV). Because the ASV is “unmanned” and is primarily controlled from a remote ground control station, several mechanisms are embedded into the design for safe and successful operations of the Ka-band terminal. Those key mechanisms are introduced in this paper as they make fault diagnosis easier and increase overall system reliability in case of primary communication channel failure.