Patent ID: 7579839

Claim:
A metal detector used for detecting a metallic target in a soil including: a. transmit electronics having a plurality of switches to generate a switched voltage signal, the waveform of the switched voltage signal being one of predetermined repeating multi-period rectangular waveforms; b. a transmit coil connected to the transmit electronics to receive the switched voltage signal and to generate a transmitted magnetic field for transmission; c. a receive coil to receive a received magnetic field and to provide a received signal induced by the received magnetic field; and d. receive electronics connected to the receive coil to process the received signal, the processing including a synchronous demodulation of the received signal using one of predetermined substantially sine-wave weighted synchronous demodulation profiles associated with a corresponding predetermined repeating multi-period rectangular waveform; the profiles being selectable by an operator; and a result of the synchronous demodulation is further processed to provide an indicator output signal in real time, the indicator output signal including a signal indicative of the presence of a metallic target in the soil.