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Tsunameter -- Tsunami Pressure Sensor
SBE 54

Print version     Current manual (older manuals)     Configuration options & accessories

SBE 54 Tsunameter Tsunami Pressure Sensor

SUMMARY

DESCRIPTION

Reliable detection of deep ocean tsunami waves without generating false alarms requires a sensor that accurately detects pressure changes of millimeter scale while sampling rapidly enough to characterize the shape of the tsunami waves and reflections in real-time. In addition to having extremely high resolution, the acquisition circuitry must be low power and free of noise, drift, and temperature-induced changes. The pressure sensor must be extremely reliable, stable, and capable of generating high resolution outputs.

The SBE 54 tsunameter continuously measures, records, and outputs pressure at user-programmable periods. Pressure resolution is better than 1 mm at full ocean depth (7000 meters) at the default 15-second sample period. The tsunami sensor's sole purpose is to function as the heart of a deep-ocean tsunami detection system. Setup and operation require no user interaction. A power supply supervisor and watchdog timer ensure automatic recovery if power or normal operation is interrupted.

The SBE 54 combines a Paroscientific Digiquartz® pressure transducer, microcontroller, real-time clock with temperature-compensated crystal oscillator, precision temperature-compensated reference frequency, two high-resolution frequency acquisition circuits, EEPROM, and FLASH memory. The reference frequency used to acquire pressure and pressure temperature outputs from the Digiquartz pressure sensor is accurate to 1 part per million and temperature calibrated to 50 parts per billion. The pressure sensor, reference frequency, and acquisition circuits are powered continuously to eliminate errors caused by start-up transients. Pressure and pressure temperature are acquired simultaneously to eliminate phasing errors and increase measurement resolution in each channel.

Low power consumption makes multi-year, battery-powered deployments practical. The FLASH memory provides four years continuous backup of the entire raw pressure record, at a 15-second sample period. Preserving the entire time series in memory allows post-deployment engineering review of the instrument’s performance, as well as scientific analysis of the entire deployment record. The EEPROM stores calibration coefficients and diagnostic information. The Digiquartz pressure sensor and frequency reference are tested and re-characterized at Sea-Bird to meet the demanding millimeter-scale sensitivity requirements.

CONFIGURATION AND OPTIONS

A standard SBE 54 Tsunameter includes:

Options include:

SOFTWARE

The SBE 54 is supplied with Windows software for instrument setup, data upload, and data conversion.

SPECIFICATIONS

Data output Real-time pressure in ASCII engineering units (dbar, psia) at user-input sample period (1 - 240 sec; default 15 sec)
Range Standard 0 to 6800 m (10,000 psia);
Optional 0 to 1300, 2000, or 4000 m (2000, 3000, or 6000 psi)
Measurement resolution * 1.1 x 10 -7 of Digiquartz pressure range at default 15-sec sample period
(0.0011 psia [0.8 mm] with 10,000 psia sensor)
Power supply 12 – 28 VDC
Power consumption 0.015 Watts at 15V, 0.016 Watts at 20V, 0.0018 Watts at 24V, 0.022 Watts at 28V
(running continuously)
Battery endurance 12 Alkaline D cells: 14 months (80% capacity)
6 Lithium DD cells: 37 months (80% capacity)
FLASH memory 8.9 million samples (51 months at default 15-sec sample period)
Reference frequency Initial accuracy: 1 ppm
Temperature characterization: ± 0.1 x 10 -6 (-10 to 30° C), ± 0.05 x 10 -6 (0 to 10° C)
Aging: 3 x 10 -6 first year, 1 x 10 -6 after first year
Real-time clock Quartz TCXO watch-crystal, accuracy ± 2 ppm (5 sec/month)
Housing 7000-meter titanium housing and end cap
Weight With optional long housing and alkaline batteries: 14.5 kg (32 lbs) in air, 8.6 kg (19 lbs) in water
* The sum of all uncertainties in a measurement of pressure change is less than 1 mm over a duration of a few minutes and less than 5 mm over a duration of minutes to hours, including ocean/instrument temperature changes of 0.25° C.


ADDITIONAL INFORMATION / LINKS:

Documentation -- manual, photos, technical papers, application notes, etc.

Sales Information -- options, accessories, cables, mount kits, spares, etc.

Software -- components of Seasoft V2

Links to Other Instruments of Interest

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Specifications are subject to change without notice.

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