Patent ID: 7755485

Claim:
A system for electronic article surveillance, the system comprising: a base station and a plurality of active RF tags being operable to attach to articles under surveillance, wherein each of said RF tags being operative to repeatedly initiate, independently from other tags and the base station, an unsolicited radio transmission of a signal having a unique identifying characteristic of said RF tag; and wherein the base station comprises a receiver operative to receive a radio transmission from a RF tag, a memory operative to store a lookup table containing a plurality of key entries corresponding to each of the plurality of RF tags, and a processor operably coupled to the receiver and to the memory, the processor being operative to obtain from the received radio transmission an identifying characteristic of an RF tag and to determine whether said identifying characteristic corresponds to one of the key entries in the lookup table, wherein, in the event said identifying characteristic corresponds to one of said key entries, the processor sets a flag associated with said one of said key entries, said flag being an indication that a positive response is associated with the RF tag from which said radio transmission is received.