TNU sensors capture snow level up to either 4 or 8 meters, according to the model in use (TNU04, TNU08). Functioning system is related to the emission of short ultrasonic frequency pulses towards the depth of snow to investigate and to the subsequent reception of the reflected wave, generated once the pulses reach the surface the snow is lying on.
It ensures excellent performance for what concerns accuracy, thanks to a system of self-correction of the level measurement. Indeed, by means of an integrated temperature sensor, it can easily take into account the variation of the sound speed as a value depending on the density of the air.
The on-board electronics calculates the level as a function of the time between the emission of the signal and the reception of pulses. In particular, TNU is equipped with an amplification and collection system specifically designed to be implemented on snow level investigations. In fact, the snow has a high sound-absorbing property (it reflects the pulse not only from the external surface, but also from the deeper layers).
A protective body composed of a special self-ventilated solar shading contains the transducer and protects it from weather conditions, allowing to achieve a proper measurement of the air temperature.
The sensor is supplied with power and signal cable (12m).