Mirror-Type Signal Transmission Network Based on Acoustic Tomography for Continually Monitoring Flow Field Real-Time

Ocean current measurement via underwater acoustic tomography network communication is an advanced technology. The mirror-type coastal acoustic tomography (MCAT) technology is proposed to measure the current field with multistation signal transmission. Here, the travel time is solved by mirror reciprocal transmission between station pairs based on three times communications. A four-station MCAT network experiment was initially performed to map the flow field variations near Liuheng Island, Zhoushan, China. The multipeak identification of the mirror transmitted signal is discussed and arrival peaks are matched via the ray simulation. The hedging and mixing progress of the 2-D current is reconstructed using the stream function inverse method. The mirror inversion results were verified to be close to the original results, but still exist the difference caused by instantaneous flow at different transmission timing. Based on the mirror transmission (MT) function, MCAT observation could obtain deep-sea environment data from distant offshore sound stations in real time. In general, this technology obtains real-time observation and measurement data by signal communication during the observation process. Compared to recycling or in situ observation, we believe such multistation MCAT networks provide long-series monitoring of some dynamic processes like internal waves, mesoscale eddies, thermocline variations, and so on.