This FAQ provides practical guidance on integrating the Seapoint Turbidity Sensor (STM-S) with the Nortek Aquadopp Profiler 2 MHz, including configuration for High Resolution (HR) mode operation 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:

• Measurement Volume: ~5 cm from sensor window (minimizes wall reflections).
• Output: Analog 0 – 5 VDC.
• Response Time: 0.1 second time constant.
• Power Supply: 7 – 20 VDC (avg. 3.5 mA, peak 6 mA).
• Gain Control: Selectable via two control lines for four sensitivity ranges.

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

To connect the STM-S to the Aquadopp Profiler, an appropriate harness and an 8/6-pin endbell configuration are required.

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

Use the Nortek Deployment Software to configure the system.

1. Connect the Aquadopp Profiler (2 MHz) to your computer.
2. Navigate to: Plan and Deploy → Hardware → External Sensor
3. Enable External Sensor.
4. Set External Sensor Type to STM-S
5. Under the Application tab: Select either Currents (Avg) or HR.
6. 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 high-resolution turbidity profiling.

Once deployed, you can monitor live turbidity data through the software:

1. Go to Show Live Data.
2. Select DF3 Sensor Data.
3. Open and enable the Data Table in the settings.
4. STM-S output will be shown as a value, which corresponds to turbidity levels (FTU)

Interpreting Turbidity Data (FTU Approximate guide):