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1Introductione project entitled “Next-generation technology for ocean resources exploration” being pursued by the Cabinet Oce’s Cross-ministerial Strategic Innovation Promotion Program (SIP) has begun developing exploration technolo-gies. An increasing need exists to transmit image data from ocean monitoring and data collected on the ocean oor to various research facilities [1][2]. Communications tech-nologies currently available in waters surrounding Japan mostly consist of satellite communication systems with transmission speeds of several hundred kbps. However, communication systems with transmission speeds of sev-eral Mbps are necessary to meet the needs mentioned above. NICT is therefore developing satellite-based high-speed communication technologies and earth stations that will enable communication at sea at transmission speeds of several Mbps.e WINDS (wideband internetworking engineering test and demonstration satellite) experiments have already achieved 3.2 Gbps data rates using an earth station equipped with a large antenna (2.4 m diameter). In addi-tion, a 51 Mbps data rate was demonstrated by accessing WINDS using a 1.2 m diameter VSAT (very small aperture terminal) set in a regenerative mode. NICT is also develop-ing land-mobile earth stations by mounting satellite track-ing antennas on ordinary vehicles to enable satellite communication. ese antennas also can be installed on marine-mobile earth stations using appropriate antenna mounts. e versatility of these antennas enables the construction of communication lines in a variety of areas. A marine mobile earth station was demonstrated in 2013 when JAMSTEC (Japan Agency for Marine-Earth Science and Technology) installed a WINDS-compatible marine earth station on its research ship Kaiyo, established a satel-lite communication line between the earth stations on the ship and on land via WINDS and remotely controlled a hybrid remotely operated vehicle (HROV), Otohime [3].NICT is studying and developing compact, light and energy-ecient marine-based earth stations that can be installed not only on research ships but also on small ships and autonomous surface vehicles (ASVs). NICT is also developing antenna system carriers that will enable accurate satellite tracking even in high wave conditions. In this project, we carried out satellite communication experi-ments at sea using a WINDS-compatible marine-based earth station. e experimental objectives were to deter-mine the station’s satellite tracking capabilities and data transmission characteristics in relation to the eects of ship movement and waves by establishing a communication line and performing communication tests. is is a report on the results of the experiments carried out jointly with JAMSTEC on its ship at sea in January and February 2016.2Experiments at seaWe carried out studies aboard the JAMSTEC research ship Mirai at sea. e ship departed from the Shinko District (new harbor district) of Yokohama and traveled around Sagami Bay and Suruga Bay. We analyzed the satel-lite acquisition and tracking performance of the on-board earth station and performed satellite communications ex-3-10 Experiment Report of Satellite Communication at the OceanNorihiko KATAYAMA, Akira AKAISHI, Toshio ASAI, Kazuyoshi KAWASAKI, Takashi TAKAHASHI, Naoko YOSHIMURA, and Morio TOYOSHIMARecently, the observation data transmission and the picture transmission for the monitoring of observation status are being considered because the development of the technology for the ocean resource exploration is advanced. NICT is developing the high-speed communication technology using a satellite because it is necessary to structure Mbps link for achieving these objectives. In this paper, we describe the results of examination to confirm a satellite tracking performance and a communication performance at the ocean.1513 Ultra-High-Speed Satellite Communication Technology