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OTT RLS - Radar Level Sensor

Non-contact level sensor for long term surface water monitoring

The OTT RLS is a non-contact radar level sensor with pulse radar technology. The OTT RLS offers a large measurement range with a small blanking distance and narrow beam width and it easily connects to most dataloggers. The RLS has extremely low power consumption and is ideal for remote or solar powered sites.

  • Surface water
  • Water level / distance to water
  • Non-contact pulse radar
  • Measures water level or depth to water from a bridge, pier or mounting arm
  • 1.3-115 ft (0.4-35 m)
  • 1.3-6.6ft: ±0.03 ft; 6.6-98.5 ft: ±0.01 ft; 98.5-115: ±0.03 ft
  • No
  • SDI-12, RS-485 (using SDI-12), or 4 ...20 mA
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For surface water level measurement of:

  • Streams and rivers
  • Tidal zones
  • Reservoirs and lakes

Ideal for monitoring:

  • Surface waters prone to flooding
  • Sediment or debris laden streams and rivers
  • Migrating channels
  • No drift over time
  • High Performance–Measurements are unaffected by air temperature, humidity, flood events, floating debris, or contaminated water; reduces the likelihood of missing data and reduces data post processing
  • Low Maintenance–Flat antenna design eliminates nesting areas for insects and periodic maintenance requirement
  • Flexible Integration/Easy Setup–Connects to most data loggers via standard communication interfaces, SDI-12 or 4 ... 20 mA; no need for additional PC software
  • Simple Installation–Light weight compact design facilitates easy mounting on bridges, extension mounting bracket or inside a small protective housing
  • Low Profile Design–Unobtrusive appearance is ideal for urban installation sites or sites prone to vandalism
  • Low Power Consumption–Ideal for remote or solar powered sites; requires only 12 mA when active
Brochure - OTT Water level measurement
OTT RLS - CE Konformitätserklärung | Declaration of Conformity | Declaration de Conformité
OTT RLS CSI Specifications
OTT RLS Manual (US)
OTT RLS Overview Video
OTT RLS Product sheet (US)
RLS – Firmware - EN
Technical Note - OTT RLS Installation
Technical Note - Sensor Selection Guide Surface Water
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Water level measurements
Measuring range 1.3-115 ft.
Transmitting Frequency 25.2 GHz Pulse Radar (FCC Version)
Resolution SDI-12 output 0.01 ft
Accuracy (SDI-12) 1.3-6.6 ft: ±0.03 ft
6.6-98.5 ft: ±0.01 ft
98.5-115 ft: ±0.03 ft
Average temperature coefficient (-10 … +40 °C) 0.01 % full scale/10 K
Accuracy (4 … 20 mA) ±0.1 % full scale
Average temperature coefficient 10 ppm full scale/°C (at 20 °C)
Measuring time 20 s
Beam angle of antenna (width of beam) 12 º
Power Requirements 5.4 to 28 Vdc
Power consumption in active mode < 15 mA @ +12 V equal to <180 mW
Power consumption in rest mode < 0.05 mA @ +12 V equal to <0.6 mW
Interfaces 4 ... 20 mA, SDI-12, RS-485 (SDI-12 Protocol)
Housing ASA (UV-stabilized ABS)
Radom (front plate) TFM PTFE
Mounting bracket 1.4301 (V2A)
Lateral axis ±90 º
Longitudinal axis ±15 º
Dimensions L x W x H 8.7 in. x 6.0 in. x7.5 in.
Weight (incl. mounting bracket) 4.6 lbs
Operating temperature: -40 ... +60 °C
Storage temperature -40 ... +85 °C
Relative humidity 0 ... 100 %
With horizontal mounting IP67 (submersion depth max. 1 m; submersion duration max. 48 h)
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