+ Problem about existing underwater communication technology



[Problem about using cable (wired) for underwater communication]

- Moving range is limited.
- Possibility of destroying natural environment by the damage of the cable or contact of the cable.

[Problem about using sound wave (wireless) for underwater communication]

- It is difficult to judge from where to hear the sound is transmitted, because the difference of the time that the sound reaches right and left ear is too short at a high velocity of about 1,500m second in water.
- Because the sound wave reflects in the shoal and the pool, it is hard to hear the sound.
- Though we often hear like "I want to do interactive communication in the sea" when diving, communication at the diving has many problems such as above so that we can say the market aiming at the leisure diver is undeveloped.

+ Solution using Underwater Visible Light Communications


(Solution #1)


(Solution #2)

(1) It is easy to move because of the wireless system.
(2) Easier adjustment, because the voice doesn't diffuse like the sound wave system.
(3) It is easy to talk because the voicing source can be checked visually by light. (It is not possible to distinguish when using sound wave system.)

+ Advantage of Underwater Visible Light Communications

- Comparison with supersonic wave communication
It is easy to catch the voice, and power consumption is less than the ultrasonic system. (The ultrasonic device can be used for 20 minutes, the Underwater Visible Light Communications can be used for 4 hours.)

- Comparison with sound wave communication (underwater speaker)
Underwater Visible Light Communications make possible to talk without any troubles to others by changing turning the source of light each other and the channel, while the sound wave communication system cannot be talked in the narrow scope with two or more people simultaneously.

- Communication by passing over the surface of the water
For instance, the conversation with helicopter for rescue can be capable from the sea. When an underwater accident occurs in the leisure diving, you can request the rescue from the water inside.