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Operation through the coupler. The signal is retrieved

Operation

Detection
of tsunamis by DART systems

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The
detection of tsunamis is carried out by the Deep-ocean Assessment and Reporting
of Tsunami (DART) solution. DART systems consist of an anchored seafloor bottom
pressure recorder (BPR) and a companion moored surface buoy for real-time
communications. Sensors that measure the pressure at fixed points on the
seafloor in a quiet environment of the deep waters.

When
tsunami occurs, the change in pressure is observed on the seafloor and detected
by the sensors. An acoustic link transmits data from the BPR on the seafloor to
the surface buoy. The BPR collects temperature and pressure at 15-second
intervals. The pressure values are corrected for temperature effects and the
pressure is converted to an estimated sea-surface height (height of the ocean
surface above the seafloor) by using a constant 670 mm Hg.

The
system has two data reporting modes, standard and event. The system operates
routinely in standard mode, in which
four spot values (of the 15-s data) at 15-minute intervals of the estimated sea
surface height are reported at scheduled transmission times the initial few
minutes, followed by 1-minute averages.

Event mode messages also contain
the time of the initial occurrence of the event. The system returns to standard
transmission after 4 hours of 1-minute real-time transmissions if no further
events are detected.

Underwater-to-surface data transmission

This
is realized by using mooring cable. In this system, data from sensor is transmitted
to the surface by applying a signal to the internal winding of a cable coupler.
This induces a signal in the single-turn secondary winding formed by the
mooring cable passing through the coupler. The signal is retrieved at the
surface by a similar configuration. This inductive modem technology provides a
convenient, economical, and reliable solution while still maintaining
flexibility.

 

Ground stations

The
TSUSAT system will use two ground stations located in South America, the main
station will work in Santiago, downloading the data collected by the
geostationary satellite. An algorithm for detecting variations in measurements
that could be potentially dangerous might be implemented in near real time in
order to have enough time to alert at the related institutions. A backup ground
station located in Lima can be used in case that the main station has a
technical disruption.

The
subsystems will be redundant being able to use different combinations of them,
just in case if one of them stops working due to technical disruptions. This
configurations will be selected by setting different modes from ground control.

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