RQ-30a Non-Contact Discharge Radar Sensor

Other models available

The RQ-30a, RQ-30a-35 and the RQ-30a-75 are sensors for continuous discharge measurement of rivers, open channels and canals with known cross-section profile. The sensors use innovative radar technology to measure velocity, water level and discharge. They…  Read more

Protection Class IP 67
  • Supply: 6 to 30 VDC 
  • Consumption at 12 VDC: standby approx. 1 mA, active measurement approx. 140 mA 
  • Over voltage protection, reverse voltage protection, lightning protection (integrated protection against indirect lightning with a discharge capacity of 0,6 kW Ppp)
Temperature and Humidity
  • Operating and storage temperature: -40 to 60 °C (-40 to 140 °F) 
  • Relative humidity: 0.. to 100 %
  • Outputs RS-485 ASCII / Modbus RTU, SDI-12 
  • Analog output: 4 to 20 mA (14 bit, max. load 250 Ω) 
  • Digital output (low: 0V, high: Vsupply, max. 1.5 A)
Material Housing material powder-coated aluminum, vandalism-proof (stainless steel option available)
Dimensions and Weight
  • L x H x W: 338 mm x 333 mm x 154 mm (13.31 x 6.06 x 13.11 in), 5.4 kg (11.90 lb) 
  • Mounting Bracket (included): Ø 34 to 48 mm
Water Level Measurement
  • Measurement range (distance between level sensor and water surface):
    • Standard RQ-30a: 0 to 15 m (0 to 49.21 ft)
    • Long Range version RQ-30a-35m: 0 to 35 m (0 to 114.83 ft)
    • Extended Range version RQ-30a-75m: 0 to 75 m (0 to 246 ft)
  • Measurement frequency: 80 GHz (standard and extended range ), 26 GHz (long range version) 
  • Resolution 2 mm 
  • Accuracy: ± 0.025 % FS Level sensor opening angle: 8° (standard and extended range), 10° (long range version)
Velocity Measurement
  • Detectable measurement range: 0.08 to 18 m/s (depending on waves) 
  • Accuracy: +/- 0.01 m/s; +/- 1 % FS 
  • Resolution: 1 mm/s 
  • Direction recognition: +/- 
  • Measurement duration: 5 to 240 s, measurement interval: 8 s to 5 h 
  • Radar: frequency 24 GHz (K-Band), opening angle 12° 
  • Vertical inclination measured internally 
  • Necessary minimum wave height: 3 mm
Automatic vertical angle compensation Accuracy +/- 1°, resolution +/- 0.1°

The RQ-30a, RQ-30a-35 and the RQ-30a-75 are sensors for continuous discharge measurement of rivers, open channels and canals with known cross-section profile. The sensors use innovative radar technology to measure velocity, water level and discharge. They enable reliable, non-contact measurement without the need for structural work in the water.

Thanks to the non-contact radar technology the RQ-30a is not susceptible to contamination, debris or driftwood in the water. Furthermore, the non-contact measurement ensures very low maintenance and fail-safe operation especially during high water or flooding.

The RQ-30a can be simply mounted on bridges, on the roofs of closed canals or channel superstructures. Depending on the properties of the water surface the device can be installed in a height of 0.5 to 35 m. The RQ-30a is available in three versions: 

  • RQ-30a: water levels from 0 to 15 meters (0 to 49.21 ft)
  • RQ-30a-35m: water levels from 0 to 35 meters (0 to 114.83 ft)
  • RQ-30a-75m: water levels from 0 to 75 meters (0 to 246 ft)

The measurable velocity range is between 0.10 and 15 m/s. Additionally the direction of flow is detected, enabling the operation in tide influenced rivers.

Measuring principle

The non-contact radar technology determines the water surface flow velocity using the Doppler frequency shift method and furthermore the water level is established by a travel time measurement. With known cross section profile the discharge Q of the water is calculated.

  • Non-contact, maintenance-free measurement system; no structural work needed 
  • Fully operating even in flood water situations 
  • Low power consumption enables operation using solar cells 
  • Detection of flow direction 
  • Recognition of hysteresis effects 
  • Measures in backwater situations 
  • Automatic installation angle correction 
  • Automatic discharge calculation based on hydraulic model with multiple k-factors 
  • Sensor self check with status and error output 
  • 3-point velocity calibration certificate 
  • Water level and velocity sensor combined in one weather and vandalism proof housing