RBRlegato4 C.T.D

Multi-channel instrument for gliders and AUVs

The RBRlegato4ย C.T.D offers a new world of measurement opportunities for gliders and AUVs. Optimised for flow dynamics, the instrument requires no pump to obtain fine structure measurements. The RBRlegato4ย provides high accuracy while consuming less power due to modern electronic design and the lack of moving parts.

  • Rated to 1250dbar
  • Pump-free design with optimized flow dynamics
  • Ultra-low power consumption
  • Multi-rate sampling up to 16Hz
  • Accurate conductivity to within 10cm of the air-ocean interface
  • Unaffected by surface contaminants or freezing conditions

Features

HIGH ACCURACY

LOW POWER CONSUMPTION

REALTIME COMMUNICATIONS

DEPTHS UP TO 1250M

MULTI-RATE SAMPLING โ‰ค 16HZ

RAPID CALIBRATION

Legato means smooth and connected. The RBRlegato4ย design and low-power operation is optimized for gliders and AUVs. The CTD is used to derive salinity, density, and sound velocity. The RBRlegato4 measures conductivity using a rugged inductive cell that is not affected by surface contaminants or freezing conditions. The CFD-optimised, low aspect ratio conductivity cell is self-flushing and does not require a pump. Using only 46mW when sampling at 2Hz or faster, and 18mJ/sample at 1Hz or slower, the power requirement is 90% lower than traditional pumped CTD sensors. When power management is critical to your mission, the lower power operation permits substantially longer deployments or higher resolution measurements. Totally silent operation is optimized for passive acoustic listening and turbulence measurements. The RBRlegato4ย is designed to fit into a standard 2″ x 7″ sensor bay and is rated to 1250m.

The RBRlegato4ย can seamlessly integrate and control your additional sensors. Using the standard RBR building-block system architecture, additional sensors such as dissolved oxygen, fluorescence, turbidity, and PAR are all supported. This sensor-hub design permits efficient system integration for vehicle integrators and users.

About the sensors

Conductivity is measured with an inductive sensor, suitable for deployment in marine, estuarine, or fresh water. There are no exposed contacts, which increases robustness, avoids susceptibility to surface contamination, and allows it to be frozen into ice without damage.

The temperature sensor is built and calibrated in-house using an aged thermistor. The temperature channel is calibrated an accuracy of ยฑ 0.002ยฐC (ITS-90) over the range -5 to +35ยฐC. Extended range calibrations are available.

Pressure is measured with a piezoresistive transducer built with a nickel-based superalloy diaphragm to avoid corrosion. Accuracy is 0.01% of the full scale rating and resolution is 0.001%.

Optional configurations

Design integration For installation in dry sensor bays
Available sensors Conductivity (C), Temperature (T), Pressure (D), Optical Dissolved Oxygen (ODO), Photosynthetically Active Radiation (PAR), Radiometer (rad), Turbidity (Tu), Backscatter (bb), Chlorophyll a, Fluorescence (Fl), pH

Specifications

Physical
Storage 240M readings
External power 4.5-30V
Communication RS-232
Clock drift ยฑ60 seconds/year
Depth rating 1250m
Housing OSP
Length 195.8mm
Width 63.8mm
Height 78.6mm
Top Curvature โŒ€220mm or โŒ€124mm
Weight ~0.8kg in air
~0.2kg in water
Sampling speed Up to 2Hz (16Hz optional)
Conductivity
Range 0-85mS/cm
Initial accuracy ยฑ0.003mS/cm
Typical stability 0.010mS/cm/year
Resolution 0.0001mS/cm
Temperature
Range -5ยฐC to 42ยฐC
Initial accuracy ยฑ0.002ยฐย (-5 to +35 ยฐC)
ยฑ0.004 ยฐC (+35 to +42 ยฐC)
Resolution <0.00005ยฐC
Time constant <1s (standard) or <0.1s (|fast16)
Typical stability 0.002ยฐC/year
Operating temperature -5ยฐC to 35ยฐC
Pressure (Depth)
Range 1250dbar
Initial accuracy ยฑ0.01% full scale
Resolution 0.001% full scale
Time constant <0.01s
Typical stability 0.01% FS
Power consumption
โ‰ค1Hz sampling 22.8mJ per sample
โ‰ฅ2Hz sampling 46mW
Sleep power 180ยตW

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