Abstract: An apparatus for detecting metallic objects of a predetermined type buried in the ground and distinguishing such predetermined objects from distributed mineral material and undesired objects. An oscillator produces a transmit signal which causes a transmit coil to generate a varying magnetic field. A receive coil coupled with the transmit coil produces a receive signal induced by the transmit signal and having components thereof corresponding to field-distorting materials in proximity to the coil. A multiple sampling circuit produces samples of the receive signal at selected times having predetermined relationships with typical characteristics receive signal components. The samples are analyzed to produce a sense signal representative of the proximity of a metallic object, and a discriminate signal representative of the type of metallic object as well as its proximity.