Prodotto

SBE-54 Tsunami Pressure Sensor

Sea-Bird Electronics

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.