Patent ID: 6927577

Claim:
A method of improving metal detection sensitivity in a pulse inductive metal detector, the metal detector including a transmitter coil configured to induce inductive target responses in a receiver coil, the method comprising: during a calibration mode (a) inducing one or more analog time-series signal responses of the receiver coil over an area known to be metal-free; (b) digitizing the one or more analog time-series signal responses; and (c) determining a digitized time-series nulling signal based on the one or more digitized time series signal responses from step (b); and then during a normal operating mode used to detect metal targets (d) inducing an analog instant time-series signal response of the receiver coil over a target search area; (e) converting the digitized nulling signal to an analog nulling signal; and (f) synchronously subtracting the analog nulling signal from the analog instant time-series signal response to produce a time-series signal response having reduced adverse ground or transmitter coil transient responses.