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The OTT SLD is an acoustic Doppler sensor system for continuous monitoring of flow velocity and water level (optional) in rivers and channels. The system guarantees reliable velocity measurements even in a flood situation with high sediment loads.

The SLD measures velocity in up to 9 adjacent cells with two horizontal beams looking sideways into the flow (Side Looking Doppler). The compact design reduces constrction efforts and allows an economic installation.

The optimised low power consumption allows an autarkic operation with a solar power system.

In combination with the Station Manager LogoSens® , the SLD can be extended to a continuously working discharge measurement system. The sensor is connected via integrated SDI-12 interface to the LogoSens®, which then calculates the discharge from water level and flow velocity and transfers the measured data via telephone, GSM or satellite to the central station.

Technical Specifications


  • Flow Velocity Measurement Principle Doppler frequency based current meter using two ultrasonic horizontal beams
  • Measuring range ±10 m/s
  • Accuracy 1 % of measured value ± 0.5 cm/s
  • Measuring frequency 0.6 MHz, beam width* 2.0°; 1 MHz, beam width* 2.3°; 2 MHz, beam width* 1.8°
  • Evaluation Measurement of the Doppler frequency in up to 9 cells, user-defined calculation of flow velocity
  • Plausibility check possible via status report
  • Water level 0….10m
  • Measuring range accuracy ±3 mm
  • Power supply 9…16 V DC
  • Power consumption 0…500 mW, depends on measuring cycle
  • Length 40 cm
  • Diameter 7.5 cm
  • * Beam width means angle to main axle. The maximum range is calculated from the angle and river profile

Data Sheet


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