Patent ID: 8659428

Claim:
An integrated electronic article surveillance (“EAS”)/metal detection system comprising: a transmitter configured to periodically transmit an interrogation signal at a first frequency and at a second frequency different from the first frequency; a receiver configured to receive a first signal at the first frequency and a second signal at the second frequency; a controller configured to detect an EAS marker based on the received first signal at the first frequency when the transmitter is not transmitting; and a metal detector module configured to detect a metal object in proximity to the integrated electronic article surveillance/metal detection system by: receiving an output of the receiver when the transmitter is transmitting; filtering out signals received substantially at the first frequency; determining a first voltage of the second signal; comparing the first voltage to a second voltage; and responsive to determining that the first voltage is different from the second voltage by more than a prescribed amount, determining that the metal object is present.