Sensors - Teledyne WORKHORSE Operation Manual

May 2015 WorkHorse H-ADCP Operation Manual

Sensors

This section describes the standard H-ADCP sensors. The PIO and DSP boards control the environmental
sensors and contain unit-specific data. Sensors include:
Temperature Sensor (Thermistor) - Used to measure the water temperature. The system uses this data to
calculate the speed of sound. This sensor is embedded in the transducer head and is not field replaceable.
Up/Down Sensor - Determines whether the transducer head is facing up or down. This sensor is located on
the PIO board.
Compass - Determines the Beam 3 heading angle of the H-ADCP using a flux-gate compass. This sensor is
located on the PIO board. The flux-gate measured earth magnetic field vector together with the tilt sensor
pitch and roll information is used to determine the heading. Since the tilt sensor data is only valid when
the H-ADCP is ±20° from vertical, the heading information is also limited to this range.
Attitude Sensor - Determines the tilt angles of the H-ADCP. This sensor is located on the PIO board. The
attitude sensor uses a pitch and roll liquid-filled sensor. This sensor is functional to an angle of ±20° from
vertical.
Pressure Sensor (optional) - Measures pressure at the H-ADCP transducer. This sensor is embedded in the
transducer head and is not field replaceable.
The CPU microprocessor controls a multiplexed analog-to-digital converter to accept analog data from the
sensors. Digital data are taken in directly. The pressure sensor incorporates a Wheatstone Bridge strain
gage to measure the water pressure at the transducer faces. Depth is calculated from pressure, with water
density adjusted by the salinity (ES) setting.
Calibration data for the sensors, a beam-angle correction matrix, and unit identification parameters
(frequency, serial number, firmware version, etc.) are stored in ROM.
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EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.