Method and system for reducing effect of interference in integrated metal detection/electronic article surveillance systems

An integrated electronic article surveillance (“EAS”)/metal detection system comprising:

• a transmitter operable to transmit an interrogation signal, the interrogation signal establishing an interrogation zone and being used to detect EAS markers and metal objects within the interrogation zone, the interrogation signal being transmitted at a first frequency during an EAS detection cycle and at a second frequency different from the first frequency during a metal detection cycle;
• a receiver operable to detect a signal received from an EAS marker;
• and
• a metal detector module operable to detect a metal object in proximity to the integrated electronic article surveillance/metal detection system, the metal detector module including a filter substantially centered at the first transmission frequency to filter out signals received substantially at the first transmission frequency during metal detection.