Real-time data acquisition from mid-ocean observatories

Abstract

Recent advances in underwater acoustic communication have enabled real-time contact with ocean bottom instrumentation. This overview talk summarizes developments in acoustic, radio, and satellite communication links and in undersea networks constructed for telemetry from mid-ocean instrumentation. Acoustic communication has made major advances in terms of energy efficiency, data rate, and robustness. Data from several experiments illustrating capabilities of the acoustic modems, algorithm structure of the communication link, and its relationship to the characteristics of the acoustic channel are presented. Technology resulting from this work is incorporated in a line of underwater modems that are being used extensively by the oceanographic community. The modems are of course useful as direct point-to-point communication devices; however, incorporating modems into communication networks greatly increases their utility. Several deployed networks are discussed, in particular an under-ice system recently develoyed on Lake Winnipesaukee and in the Arctic off Pt. Barrow. The under-ice network is a part of the Autonomous Oceanographic Sampling Network (AOSN), a long-term development program aimed at improving the timeliness and cost-effectiveness of oceanographic data acquisition.