Discover the SHM31 — Lufft’s Snow Depth Sensor

Precise determination of snow depth is a central indicator for many global weather application decisions. OTT HydroMet sensors have become the standard for meteorological measurements in climate research, flood and avalanche risk detection, and winter sport/traffic safety assessments.

With thousands of installed instruments on every continent, both the Lufft SHM 31 and its predecessor model, the SMH 30, have established themselves as the standard for precisely measuring the depth of snow. Its powerful laser sensor measures the density of snow from above, without the need for contact; it is designed to be safe for eyes (class-2 laser) and, thanks to its builtin
heating module, it requires no maintenance.

However, its distinct quality is found in its millimetre-precise measurement of layers of snow – regardless of prevailing weather conditions. In this way, the Lufft SHM 31 offers the optimal requirements for reliably collecting highlyprecise measurement data and processing it in the course of further methods.

  • Parameters measured: Snow depth
  • Interfaces: RS485 and RS232 with Modbus RTU, UMB, UMB-ASCII 2.0, and SDI12 protocol
  • Measurement technology: Optoelectronic measuring technique (rangefinder; laser distance sensor) with an eye-safe laser
  • Article number: 8365.30
  • Product highlights: Long-distance snow depth measurement, heating options that enable accurate measurements in all weather, and easier installation due to the automated inclination angle compensation

Advantages of the Snow Height Sensor Lufft SHM31

  • Compact and weatherproof housing
  • The optical measurement approach has a significant advantage over traditional ultrasonic sensors in that it is not affected by changes in temperature or wind
  • Long-range, millimeter-accurate snow level measurement
  • Installation is made simpler by the built-in automated angle meter
  • Maintenance-free operation: No calibration or exchange of desiccant
  • Identifying snow as distinct from other natural surfaces
  • Effective suppression of scattered light
  • The laser diode’s lifespan is significantly increased by a variety of heating features, which also enable accurate measurement data in all-weather situations

Examples of Use

Examples of Use of the Snow Height Sensor Lufft SHM31

The SHM31 is used in the following examples of applications:

  • Traffic and aviation safety, road surveillance
  • Water and energy related applications/industry
  • Part of (alpine) meteorological observation stations from weather services around the world
  • Snow level detection for winter sports areas


Product Calibration.

Product Calibration. Image Credit: OTT HydroMet

Mounting clamp, steel.

Mounting clamp, steel. Image Credit: OTT HydroMet

Reference target plates.

Reference target plates. Image Credit: OTT HydroMet

Connection cable for SHM31.

Connection cable for SHM31. Image Credit: OTT HydroMet

Technical Data

Source: OTT HydroMet

Dimensions (LxWxH) 302 × 130 × 234 mm
Weight 2.35 kg
Operating parameters
Temperature range -40 ... +50 °C
Relative humidity 0 ... 100%
Measuring parameters
Snow Depth 0 ... 15 m
Mounting distance to surface 0.1 ... 16 m
Accuracy (snow depth)2 ± (5 mm + 0.06%)
Repeatability 0.6 mm
Intermediate precision/ reproducibility 5 mm
RS485 Modbus RTU , ASCII, UMB protocol
RS232 ASCII protocol
SDI-12 SDI-12 protocol
Data transfer mode Polling (UMB, ASCII, SDI-12); Auto telegram output (ASCII)
Electrical parameters
typ. power consumption at 24VDC and 10 s measurement interval without heater: approx. 0.7 W; with window heating: approx. 3.4 W
Power supply 12 or 24 VDC, tolerance +/- 15%
Maximum power consumption (connecting power with heater on) 18 W
Laser classification Laser class 2 (IEC 60825-1:2014);
complies with 21 CFR 1040.10 except for deviations pursuant to Laser Notice No. 50, dated June 24, 2007
Protection class IP68
EMC EN 61326-1:2012 (industrial standard)
EC 2014/30/EU & RoHS 2011/65/EU

Discover the SHM31—Lufft’s Snow Depth Sensor

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