AM Tags For Wal-Mart
S-4 PANKAJ PLAZA, PLOT NUMBER-7, SECTOR-12 OPPOSITE METRO STATION , DWARKA NEW DELHI-110078(INDIA) (Anti-shoplifting Devices Work) A typical AM tag from Wal-Mart Acousto-magnetic System The newer acousto-magnetic system , which has the ability to protect wide exits and allows for high-speed label application, uses a transmitter to create a surveillance area where tags and labels are detected. The transmitter sends a radio frequency signal (of about 58 kHz) in pulses, which energize a tag in the surveillance zone. When the pulse ends, the tag responds, emitting a single frequency signal like a tuning fork. While the transmitter is off between pulses, the tag signal is detected by a receiver. A microcomputer checks the tag signal detected by the receiver to ensure it is at the right frequency, is time-synchronized to the transmitter, at the proper level and at the correct repetition rate. If all these criteria are met, the alar...