Schelt Technology

Continuous water- level and snow depth meas-urements are very important in water resource man-agement and avalanche risk forecast.
The USH-9 is a continuous measurement device forthe contact-free determination of water level and
snow depth. It measures the transit time of an ultra-sonic signal between a variable surface and the
USH-9 sensor, and translates it to a level or dis-tance. An integrated processor compensates the
detected signal for temperature and filters inter-fering reflections of precipitation within the meas-urement path.
The USH-9 sensor contains an additional feature tosense precipitation and thus offers the option todetect the settling of snow. Therefore, the sensormay also be implemented in observation systemsthat monitor road conditions.

The SnowPackAnalyser measures thevolumetric contents of ice, water and airtogether with the snow depth and calculatesthe SWE and the snow density.

The SL300 ultrasonic snow depth sensor provides a total system in a compact package,containing an ultra sensitive electrostatic transducer and the supporting circuitry to provide a 0to +5 or 0 to +2.5 VDC output with fully independent zero and span adjustments over the entireoperating range of detection from 1.5’ - 32’.The piezoelectric crystal inside the transducerconverts electrical pulses into sound energy thattravels in the form of a wave at the establishedfrequency and at a constant speed in a givenmedium.The ultrasound waves are emitted in bursts andreceived back at the transducer as echoes. Theinstrument measures the time for the bursts totravel down to the reflecting surface and return.This time will be proportional to the distance fromthe transducer to the surface and can be used todetermine the level of water or snow.The speed of sound through the medium (air)varies with the medium’s temperature. SL300contains a temperature sensor to compensate forchanges in operating temperature that wouldalter the speed of sound and hence the distancecalculation that determines an accurate levelmeasurement.