Oceanographic instrument

Definition of Oceanographic instrument: An oceanographic instrument is a device that allows to measure one or more properties of seawater in situ. This is the common definition for Oceanographic instrument, other definitions can be discussed in the article

Overview

Schematic of a generalised oceanographic instrument. The analyte (property to be measured) interacts with the detector (in some cases after a stimulus has been exserted by the instrument). The detector produces a signal, that is transformed into an electrical signal by the transducer. Detector and transducer together constitute the sensor. The electrical signal is fed to the signal processing (and conditioning) unit that creates the signal output of the instrument.

An oceanographic instrument generally consists of one or more sensors and a signal processing unit that converts the sensor signal and carries out scaling and conversion to engineering units and the output data protocol.

Oceanographic instruments can contain data loggers to store measurement data for readout after the deployment.

Important properties

• Accuracy: deviation of the measured value from the true value
• precision: deviation of a measured value from another measured value of the same quantity (but at different environmental conditions (e.g. the two measurements taken at different temperatures)
• resolution: smallest change in the measured quantity that can be detected by the instrument
• measurement rate: number of measurements that can be carried out per time unit (e.g. measurements/hour)
• power consumption: mean of electrical power uptake during deployment (usually in Watts [W])
• deployment time: time period for which the instrument can be deployed (usually depends on environmental conditions, such as biofouling, or on stored energy and power consumption)

(see also important properties of sensors)