The Numis lite device is a Magnetic Resonance Sounding (MRS) system for the direct detection of shallow groundwater down to 50 m of depth.

This compact MRS equipment features:
• a converter/tuning unit powered by two 12 V batteries,
• a transmitter-receiver unit for pulse generation and signal measurement,
• a wire loop used as a transmitting and a receiving coil,
• a PC computer for the control of the whole system, and for data processing and interpretation

The MRS method is the only non-invasive method which directly studies groundwater reservoirs from surface measurements:
A pulse of current, at a given frequency is transmitted into a loop. The protons of the groundwater are excited. The signal produced during their return to equilibrium is measured with the same loop. To realize a sounding, different pulse moments (A.ms) are injected in the loop, all corresponding to different investigation depths.

This measure gives access to the soil water content (%) and is related to the mean pore size (permeability).