Integrating the Seapoint Turbidity Sensor (STM-S) with the Aquadopp Profiler & the Vector Generation 2

This FAQ provides practical guidance on integrating the Seapoint Turbidity Sensor (STM-S) with the Nortek Aquadopp Profiler and the Vector generation 2, including functionality for  our High Resolution (HR) mode instruments and synchronized data sampling.

What is the STM-S?

The STM-S is a high-sensitivity optical sensor designed to measure turbidity by detecting scattered infrared light from suspended particles in water.

Key Features:

• Sensing Range:
  • Linear range (S signal): 0 – 1250 FTU
  • Extended range (2nd order & exponential): up to 50,000+ FTU
• Output: 0 – 5 VDC (RS-232 serial)
• Response Time: 0.1 second time constant
• Power Supply: 4.8–20 VDC (35 mW average)
• Depth Rating: 6000 m
• Gain Control: 4 sensitivity levels via two control lines
• Sensing Distance: < 5 cm from window (optically confined)
• Materials: Rigid polyurethane, corrosion-free
• Ambient Light Rejection: Insensitive to ambient light
• Compliance: CE and RoHS

Warning: Do not exceed 20 VDC or apply voltage to the output pin — this will damage the sensor.

How to Configure the Aquadopp Profiler or the Vector Generation 2 for STM-S Integration (HR-Compatible):

Use the Nortek Deployment Software to configure the system.

1. Connect the instrument under test to your computer.
2. Connect the STM-S external sensor to the instrument into the 6-pin connector.
3. Navigate to: Plan and Deploy → Hardware → External Sensor.
4. Enable External Sensor.
5. Set External Sensor Type to STM-S.
6. Under the Application tab: Select Currents or HR mode (Aquadopp specific).
7. Configure the instrument as required for the deployment.

The STM-S provides continuous analog output with no internal delay, so it supports synchronized sampling up to 8 Hz for the Vector Generation 2 and 1 Hz for the Aquadopp profiler (8 Hz in High resolution mode).

Once deployed, you can monitor live turbidity data through Nortek Deployment via "advanced mode" which can be activated in the "software" panel found in the bottom left corner of Nortek Deployment:

1. Go to show live data - run current configuration.
2. Select raw data.
3. Locate the external sensor data.
4. STM-S output will be shown as a value, which corresponds to turbidity levels (FTU).

Interpreting Turbidity Data (FTU this is just a guide and the data should be interpretated via the supplier of the STM-S sensor):