DeTeC (Demining Technology Center) is developing a sensor system for humanitarian demining enabling reduction in the number of false alarms and usable by a man or an autonomous robot (see http://diwww.epfl.ch/lami/detec/). We have chosen to concentrate our first experiments on a commercial impulse ground penetrating radar with a 1 GHz antenna and a metal detector used for imaging purposes. The metal detector should help to distinguish two objects with similar radar echoes but different metal content, e.g. a mine and a stone of the same size. The GPR should in turn differentiate a mine from metallic debris, which often gives a similar metal detector answer. An experimental setup, consisting of a double sandbox with a computerized system that allows the automated positioning of the sensors, has been constructed. Preliminary results of data acquisition and treatment on both sensor technologies are presented with a comparison between the metal detector and the GPR data.