Abstract: A method and system are provided for canceling interference signals from a received signal. A ratio module receives as input a ratio of a filtered receiver output signal level and a filtered transmitter output signal level. A product module receives as inputs an output of the ratio module and a transmitter output. The product module calculates a product of the output of the ratio module and the transmitter output. An adjusted receiver signal module receives a difference calculated from the received signal level and the output of the product module. The method and system are suitable for use in a metal detection subsystem with a larger security system.

Abstract: An electronic article surveillance (EAS) antenna system including at least one transmit antenna and at least one amorphous core receiver antenna adapted for installation on the floor, in the grout region of the floor, or under the flooring of a passageway. An EAS system including at least one perimeter loop antenna adapted to extend around the entire perimeter of a passageway is also provided. The system may further include at least one floor antenna adapted for installation within a region of a floor of a passageway and at least one ceiling antenna adapted for installation adjacent a ceiling of the passageway.

Abstract: An electronic article surveillance (EAS) antenna system including at least one transmit antenna and at least one amorphous core receiver antenna adapted for installation on the floor, in the grout region of the floor, or under the flooring of a passageway. An EAS system including at least one perimeter loop antenna adapted to extend around the entire perimeter of a passageway is also provided. The system may further include at least one floor antenna adapted for installation within a region of a floor of a passageway and at least one ceiling antenna adapted for installation adjacent a ceiling of the passageway.

Abstract: An EAS transmitter for generating an EAS transmission with a preselected guardband, comprises an oscillator for generating a fundamental frequency pulsed waveform and circuitry for effecting spectral window shaping of the fundamental frequency waveform on a time basis corresponding with the guardband for reducing sidelobe energy in the guardband. The transmitter may further include circuitry operative on the spectral window-shaped fundamental frequency waveform for further reducing sidelobe energy of the spectral window-shaped fundamental frequency waveform in frequency correspondence with the guardband. Another EAS transmitter comprises a storage unit having stored therein the sidelobe energy-reduced spectral window-shaped fundamental frequency waveform and obtaining EAS transmissions by use of the stored contents of the storage unit.

Abstract: An apparatus for synchronized operation of a plurality of EAS systems. The system includes two or more EAS systems. Each EAS system has a receiver for receiving the same RF synchronization signal sent from a remote source, a transmitter for transmitting a marker exciter pulse and an exciter pulse receiver. The transmitter and exciter pulse receiver of each of the EAS systems are selectively enabled a predetermined time after receiving the RF synchronization signal so that all EAS systems in a localized area can be synchronized with one another.

Abstract: An electronic article surveillance system includes generating circuitry for generating an interrogation signal. The generating circuitry includes an interrogation coil for radiating the interrogation signal in an interrogation zone. A marker is secured to an article appointed for passage through the interrogation zone, and includes an active element for generating a marker signal including harmonic signal components at harmonics of an operating frequency of the generating circuitry. Detecting circuitry detects the harmonic signal components of the marker signal generated by the active element. The generating circuitry generates the interrogation signal in the form of discrete pulses and the detecting circuitry is operated concurrently with the generating circuitry.

Abstract: An EAS system in which first and second received signals are independently front-end processed to produce third and fourth signals indicative of the absolute values of the first and second processed signals. The third and fourth signals are then combined and the combined signal passed to a tag evaluation processor for time and frequency domain processing for evaluating whether a tag is present in an interrogation zone. The front-end processing is carried out in such a way that interference signal content including shield interference is extracted without extracting tag signal content in the received signals over a period of time. In this way, the first and second transmitter antennas of the system can be driven with drive signals having a phase difference of other than 0.degree. or 180.degree. and the tag evaluation processing can be carried out during the entire period of the drive signals.