Acoustic Telemetry in an Automated System for Long-Term Ocean Data in Real Time

An Acoustic Telemetry Data Link (ATDL) has successfully completed a 5-month at-sea evaluation as part of a fully automated system for acquiring and real-time reporting of data from seafloor or mid-water instrumentation. Inherent in real-time data is the up-to-date verification of system function and data quality throughout the deployment, as opposed to recorder systems for which verification is generally possible only after a successful recovery of the mooring. As compared to hardwired links, the ATDL system avoids long-term mortality at the buoy/sea interface as well as the inadvertent coupling of sea surface wave energy to the subsurface instrumentation. Hourly messages of 122 bytes were transmitted acoustically at 600 bits per second to a moored NOAA data buoy for radio relay to shore via the GOES system. Error-free messages were obtained in real-time response to 97.3 percent of interrogations by the automated buoy payload in seas up to 4 meters and winds up to 16 meters per second. Also demonstrated was the system´s ability to acquire, store, and relay data missed in real time.