Title :
New generation CTD system [conductivity-temperature-depth sensor]
Author_Institution :
EG&G Ocean Products Inc., Cataumet, MA, USA
fDate :
7/1/1988 12:00:00 AM
Abstract :
A microprocessor-based CTD (conductivity-temperature-depth) sensor unit is described in which the microprocessor is used to vary the analog-to-digital conversion process to achieve 16-bit resolution at a measurement rate of 500 measurements per second, or 18-bit resolution at 30 measurements per second. Software control of resolution, sampling rate, and sampling sequence permit the sensor unit to be software-configured for a wide variety of missions. Pressure and conductivity sensors are expected to substantially improve the system accuracy. The conductivity cell design has six electrodes which are all relatively remote from the external measurement volume (approximated by a 2-cm diameter sphere). This so called recessed-electrode concept is expected to eliminate calibration drift due to contamination of the electrodes and the insulating surfaces of the cell, thus ensuring excellent long-term stability
Keywords :
analogue-digital conversion; computerised instrumentation; electric sensing devices; electrical conductivity measurement; microcomputer applications; oceanographic equipment; temperature measurement; 16-bit resolution; 18-bit resolution; analog-to-digital conversion process; calibration drift; conductivity cell; conductivity temperature depth sensor; long-term stability; recessed-electrode; Analog-digital conversion; Calibration; Conductivity measurement; Electrodes; Microprocessors; Pollution measurement; Sampling methods; Sensor phenomena and characterization; Sensor systems; Volume measurement;
Journal_Title :
Oceanic Engineering, IEEE Journal of
