RBRcoda Tu

The RBRcoda Tu (Fig. 8) is a realtime turbidity sensor with two independent optical channels for optimising linearity and sensitivity. Its high dynamic range permits exposure to full sunlight with very low detection limits, while power consumption and depth rating have been tailored for use in a wide variety of applications.

The turbidity channel of the RBRcoda Tu ensures high sensitivity in the low range (0-1000FTU), while the optical backscatter channel is designed for high-turbidity applications (up to 20000FTU). RBR calibrates the optical backscatter channel to ensure the highest accuracy around and above 1000FTU, thus achieving alignment between these two channels through their intended measurement conditions.

All optical components of the RBRcoda Tu are robust and durable, selected to minimise ageing due to UV/sunlight exposure, and thus show no change in properties over extended deployments. Its sapphire windows facilitate automated cleaning by a wiper to keep them free of biofouling during long-term moored deployments.

When used as a standalone sensor, the RBRcoda Tu has the additional capability to sample in aggregate mode. See Ruskin User Guide: Sensors for details.

RBRcoda.Tu.8.png
Fig. 8.    RBRcoda Tu

Turbidity

Parameter Value

Channel wavelength

880nm

Centroid angle

90°

Linearity, R2

0.99

Initial accuracy

5%

Calibrated range1

0-1000FTU

Measurement range1

0-1500FTU

Detection limit

0.005FTU

1 Response becomes non-linear above 1000FTU.

Turbidity (optical backscatter)

Parameter Value

Channel wavelength

880nm

Centroid angle

135°

Linearity, R2

0.99

Initial accuracy

5%

Calibrated range1

1000-4000FTU

Measurement range1

0-20000FTU

Detection limit

2.0FTU

1 Response is linear between 500 and 15000FTU.

Physical

Parameter Value

Connector

MCBH-6-MP

Communications

RS-232

Housing

Titanium

Diameter

25mm

Length

~70mm (~105mm with connector)

Weight

110g in air, 70g in water

Depth rating

Up to 6000m

Sampling rate

Up to 32Hz

Power

Parameter Value

Supply voltage

4.5V to 30V (12V nominal)

Power

3mJ/sample (4Hz or slower)
5mA (60mW) (8Hz or faster)

Sleep current

10μA

Calibration equations

Turbidity

\[Tu_{(FTU)}=C_0+C_1*V_r\]

Backscatter

\[BB_{(m-1sr-1)}=C_0+C_1*V_r\]