"How is sound used to transmit data underwater?" (continued)

The same technology can be used to study undersea volcanoes. The New Millennium Observatory Network (NeMO Net) is another exciting project conducted by NOAA. NeMO Net is a two-way communication system which links monitoring instruments on an active submarine volcano to the Internet. This system uses acoustic modems to relay data from instruments on the seafloor to a buoy at the surface, which in turn sends the data to researchers at NOAA's Pacific Marine Environmental Laboratory in Oregon via satellite. For more information on the New Millennium Observatory Network visit http://www.pmel.noaa.gov/vents/nemo/index.html.

NeMo Net System. A camera on the seafloor takes 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.

Another practical example for the use of acoustic communication technology is in the search for underwater objects. A robot crawler carries a modem, a camera, and a digital signal-processing unit. The robot, transversing the seafloor, searches for an object. When an object is found, the robot sends an acoustic signal to a ship or shore based station. The robot can then be commanded to take a still frame photo, compress it and transfer the image to an acoustic signal that is sent back to the investigator. This technology will allow archaeological expeditions to save thousands of dollars in diving time.

Robotic crawlers can carry sensors into very shallow water, or even into the surf zone. This robotic crawler, equipped with a camera and modem, can be controlled from substantial distances via acoustic communications. Photo courtesy of Benthos and the Naval Coastal Systems Station.


top of page

~ To text-based Site Map ~