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Naha-shi, Japan

Patent
Marine Comms Ryukyu Inc | Date: 2012-06-18

A simple visible light communication method and system that, underwater in an ordinary water-quality in which a diver is allowed to go under the water, are able to reliably communicate with a ship, or the like, above water while the diver is stopping at a safety stop position at a depth of 5 m in order to prevent occurrence of dysbarism. The visible light communication method and system us the visible light communication system that includes a transmitter and a receiver and that is usable underwater, and include at a transmitting side, modulating information to be transmitted to pseudo-white light that is adjusted to have a color temperature of 4000 to 10000K and a luminous flux of 550 to 1500 lumens and that is emitted from an LED, and transmitting the pseudo-white light; and, at a receiving side, extracting the information by demodulating the received pseudo-white light.


Uema H.,Marine Comms Ryukyu Inc. | Matsumura T.,Marine Comms Ryukyu Inc. | Saito S.,Marine Comms Ryukyu Inc. | Murata Y.,Marine Comms Ryukyu Inc.
Electronics and Communications in Japan | Year: 2015

The main subject of this investigation is to perform research and development and verification experiments on underwater communications (underwater visible light communications; VLCs) under the assumption that VLC can be used for tourism and environmental protection under the ocean conditions of the Okinawa region (Zamami village), which is one of the most popular diving spots, with the most transparent water and abundant coral and fish. Radio is rarely used as a communications tool underwater because the attenuation rate of radio signals is high. The only communications tool now available under water is sonic (ultrasonic) communications, although it has not spread among divers because it is subject to noise from reflections of thewater surface or the sea floor, and its use is not simple. Another disadvantage of this mode of communication is that it is very difficult to identify the speaker when several divers are present in the same area. With the underwater VLC device, most of the underwater communications problems are already solved, for the following reasons: (1) the device is easy to move and does not involve cables; (2) it is much easier to capture another person's words because communication does not diverge as sonic communication does; (3) conversation is much easier since the other party can recognize the speaker visually. © 2015 Wiley Periodicals, Inc. Source


Uema H.,Marine Comms Ryukyu Inc. | Matsumura T.,Marine Comms Ryukyu Inc. | Saito S.,Marine Comms Ryukyu Inc. | Murata Y.,Marine Comms Ryukyu Inc.
IEEJ Transactions on Industry Applications | Year: 2013

The main subject of this research and development is to make the research and development and proving experiment of the underwater communications (underwater visible light communications = VLC) with the premise of utilization of VLC for tourism and environmental protection, in the oceanic conditions of Okinawa area (Zamami-village) that obtains one of the highest popularities as a diving spot which has the highest transparency of water and gathers lots of coral and fish. Radio communication is rarely used as a communications tool underwater because the attenuation rate of radio signal is high. At this moment the only communications tool available in the water is the sonic (ultra-sonic) communications, though, it has not spread out among the divers since it is subject to noises from the reflections of water surface or the bottom of the sea and the handling is not that easy. Another disadvantage of this mode of communication is that it is very difficult identity the speaker when several divers are present in the same area. With the underwater VLC device, most of the underwater communications problems are already solved with the following reasons: (1) easy to move and act without cables; (2) it is easier to catch the other buddy's words since it doesn't spread out like sonic communications; (3) conversation is much easier since the buddy can recognize the speaker with eyes. © 2013 The Institute of Electrical Engineers of Japan. Source

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