Patent ID: 7078906

Claim:
A metal detector configured to operate in both a time-domain mode and a frequency-domain mode, the metal detector comprising: a transmitter comprised of: a transmitter coil; a generator for generating an oscillatory wave current signal to be applied to the transmitter coil for operating in the frequency-domain mode; a direct current source for generating a current signal to be applied to the transmitter coil for operating in the time-domain mode; means for combining the oscillatory wave current and direct current signals into a single composite transmitter current signal; and a transmitter coil switch for switching the single transmitter current signal on and off to the transmitter coil, and a receiver comprised of: a magnetic field detector for sensing eddy currents in nearby metal targets; first receiver components configured to operate in the time-domain mode to detect metal targets; and second receiver components configured to operate in the frequency-domain mode to detect metal targets, wherein the metal detector operates in (i) the frequency-domain mode while the transmitter coil switch is on to charge the transmitter coil with the direct current signal, and (ii) the time-domain mode while the transmitter coil switch is switched off.