Acoustic Modem

An acoustic modem is used to transmit data underwater, much as telephone modems are used to transmit data over phone lines. An acoustic modem converts digital data into special underwater sound signals. These signals are then received by a second acoustic modem and converted back into digital data. Acoustic modems can be used for underwater telemetry, ROV and AUV command and control, diver communications, underwater monitoring and data logging, and other applications requiring underwater wireless communications.

Courtesy of Link-Quest Inc.

The New Millennium Observatory Network (NeMO Net) is an exciting new project conducted by the US National Oceanic and Atmospheric Administration (NOAA) that uses acoustic modems to transmit data. NeMO Net is a system, which transmits temperature and pressure data daily from Axial Volcano, 250 miles offshore of Oregon and 1 mile underwater along the Juan de Fuca Ridge. NeMO scientists study the dynamic interactions between submarine volcanic activity and seafloor hot springs. NeMO Net uses acoustic modems to send data from the monitoring instruments located on the seafloor to surface buoys. These buoys then relay the message via one of two satellite systems to NOAA's Pacific Marine Environmental Laboratory. For more information visit http://www.pmel.noaa.gov/vents/nemo/index.html.

NeMo Net System. A camera on the seafloor pictures and measures temperature at a hydrothermally active area on the seafloor. Data are sent acoustically through the water to a surface buoy, and then via a satellite to researchers on land. Illustration courtesy of NOAA Pacific Marine Environmental Laboratory Vents Program.


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