Fast and Reliable Underwater Communication: Successful Applications of Biologically Inspired Techniques

The capability of the Sweep Spread Carrier (S2C) technology to overcome even the most crucial problems occurring in noisy ultra-shallow water channels could be shown in a wide range of technical applications. A milestone was the first real time transmission of side-scan sonar data while sea-floor mapping carried out by the AUV HUGIN 1000 running several hundred meters in front of the supply ship at a depth of 100–200 m (water depth ca. 400 m). Data speed was between 20 and 33 kBit/s in this trial. Based on this experience a new protocol providing two communication layers has been developed which allows to interpose high priority messages into an ongoing data stream when ever appropriate. So the S2C modems can be used for the transmission of large data files (measurements, digital images etc.) while serving as a fast and reliable control or command link, simultaneously. Current developments include integrated communication, tracking and positioning (combination with an USBL module) and enhanced networking capability. Various models ranging from high-speed S2C modems for short distance application (up to 72 kBit/s over several hundred metres) to efficient long-range modems became available. One of our latest models, the S2C M 7/17, is currently tested in the German Tsunami warning system in the Indian Ocean. The two directional acoustic link between the ocean bottom unit (OBU in 5000–6000 m depth) and the satellite buoy at the surface will be fast enough to transmit not only pressure data but also the records of 4 high-resolution seismic channels including the pre-history of a given Tsunami event. Via satellite scientists have permanent access to the OBU and can thus analyse any event of interest. This new technology opens many possibilities also for applications in Offshore Mechanics and Arctic engineering. Worthwhile to be mentioned, just the other day also the acoustic data transfer via the mud inside of a drill pipe was managed by using the S2C technique.