Pulse transmission synchronization

摘要

Interference in an electronic article surveillance (EAS) system is reduced by transmitting warning pulse at a predetermined time following the EAS marker exciter pulse. The predetermined time and duration of the warning pulse are chosen so that the warning pulse acts upon a noise interference avoidance process in a second non-cooperative EAS unit. More particularly, the warning electromagnetic pulse causes a timing change in a second synchronized electromagnetic exciter pulse produced by the second EAS unit when the second synchronized electromagnetic exciter pulse is concurrent with the first receive interval. This timing change causes the second EAS unit to no longer interfere with the first EAS unit.

主权项

1. A method for reducing interference in an electronic article surveillance (EAS) system, comprising:
performing marker tag detection operations in a first EAS unit including
periodically generating with a transmitter a first synchronized electromagnetic exciter pulse configured to force a response in said marker tag when said first synchronized electromagnetic exciter pulse is transmitted into an EAS tag detection zone,communicating said first synchronized electromagnetic exciter pulse into the EAS tag detection zone during a pulse transmit time, andafter termination of said pulse transmit time, monitoring with a receiver to detect said response from said marker tag during a first receive interval; selecting a predetermined time and a duration of a first warning electromagnetic pulse so that said first warning electromagnetic pulse will be transmitted from the first EAS unit concurrent with a second receive interval of a second EAS unit which follows a second synchronized electromagnetic exciter pulse produced by the second EAS unit when the second synchronized electromagnetic exciter pulse is concurrent with said first receive interval, where the second EAS unit performs monitoring operations during the second receive interval to detect a marker tag's response to the second synchronized electromagnetic exciter pulse; and transmitting with said first EAS unit the first warning electromagnetic pulse at the predetermined time, where the first warning electromagnetic pulse acts upon a noise interference avoidance system in the second EAS unit so as to cause an automatic synchronization of transmit and receive operations of the second EAS unit with transmit and receive operations of the first EAS unit in response to the second EAS unit's reception of the first warning electromagnetic pulse during the second receive interval.