Abstract: A method and electronic article surveillance (“EAS”) system reduce interference. The EAS system includes a detection zone. At least one reference pattern of transmission windows for an interfering EAS system is provided. The reference pattern indicates a sequence of time slots for which the interfering EAS system is transmitting. A sample pattern of signals is received. Each signal has a corresponding amplitude. The received sample pattern is compared to the at least one reference pattern. Responsive to determining that the received sample pattern matches the at least one reference pattern, the at least one reference pattern is used to trim samples received during receive windows corresponding to the time slots for which the interfering EAS system is transmitting.

Abstract: A magnetic core transceiver antenna for EAS marker detection is provided. The core includes a stack of amorphous alloy ribbons insulated from each other and laminated together. A coil winding of wire, also insulted from the ribbons, and connected to an electronic controller provides the transmitter and receiver modes. The transceiver antenna is optimized for the dual mode operation, and is smaller and uses less power than conventional air-core EAS antennas with equivalent performance. Complex core geometries, such as a sandwiched stack of different sized ribbons, can be implemented to vary the effective permeability of the core to customize antenna performance. Multiple transceiver antennas can be combined to increase the size of the generated EAS interrogation zone.

Abstract: A method and electronic article surveillance (“EAS”) system reduce interference. The EAS system includes a detection zone. At least one reference pattern of transmission windows for an interfering EAS system is provided. The reference pattern indicates a sequence of time slots for which the interfering EAS system is transmitting. A sample pattern of signals is received. Each signal has a corresponding amplitude. The received sample pattern is compared to the at least one reference pattern. Responsive to determining that the received sample pattern matches the at least one reference pattern, the at least one reference pattern is used to trim samples received during receive windows corresponding to the time slots for which the interfering EAS system is transmitting.

Abstract: A magnetic core antenna system including a magnetic core and a winding network. The winding network may be configured with a non-uniform ampere-turn distribution to achieve a desired flux density in the core. The network may include a plurality of windings configured to provide a winding impedance facilitating optimal transmitter power delivery to the windings. A magnetic core may be constructed from multiple components having longitudinal contact surfaces and joined by a transverse clamping force. An air gap may be provided between the components to allow relative movement therebetween.

Abstract: A system for minimizing the effect of null zones in an interrogation zone of a marker detection system. The system includes a reference antenna system configured to produce a first reference electromagnetic field during a first time period. The antenna system also includes a phase canceling antenna system configured to produce a second electromagnetic field substantially in phase with the reference electromagnetic field during the first time period and a third electromagnetic field substantially out of phase with the reference electromagnetic field during the first time period. The phasing of the first field or the second and third fields may be continuously switched while the phase of the other is held constant. A method of spatially shifting null zones in an interrogation zone of a marker detection system is also provided.

Abstract: An EAS or RFID system including first and second core antenna systems. The first and second antenna systems establish magnetic fields having opposite directions and are positioned so that the fields at least partially cancel outside of an interrogation zone for detecting an EAS or RFID tag. There is also provided an EAS or RFID wherein the magnetic field direction established by a core antenna is varied at certain time intervals to minimize the effects of null zones in the interrogation zone.

Abstract: An EAS or RFID system including first and second core antenna systems. The first and second antenna systems establish magnetic fields having opposite directions and are positioned so that the fields at least partially cancel outside of an interrogation zone for detecting an EAS or RFID tag. There is also provided an EAS or RFID wherein the magnetic field direction established by a core antenna is varied at certain time intervals to minimize the effects of null zones in the interrogation zone.

Abstract: A magnetic core antenna system including a magnetic core and a winding network. The winding network may be configured with a non-uniform ampere-turn distribution to achieve a desired flux density in the core. The network may include a plurality of windings configured to provide a winding impedance facilitating optimal transmitter power delivery to the windings. A magnetic core may be constructed from multiple components having longitudinal contact surfaces and joined by a transverse clamping force. An air gap may be provided between the components to allow relative movement therebetween.

Abstract: A magnetic core transceiver antenna for EAS marker detection is provided. The core includes a stack of amorphous alloy ribbons insulated from each other and laminated together. A coil winding of wire, also insulted from the ribbons, and connected to an electronic controller provides the transmitter and receiver modes. The transceiver antenna is optimized for the dual mode operation, and is smaller and uses less power than conventional air-core EAS antennas with equivalent performance. Complex core geometries, such as a sandwiched stack of different sized ribbons, can be implemented to vary the effective permeability of the core to customize antenna performance. Multiple transceiver antennas can be combined to increase the size of the generated EAS interrogation zone.

Abstract: A method for wireless synchronization of a first and second magnetic electronic article surveillance (EAS) systems arranged for operation in close proximity to one another. The method includes the steps of programming each of the first and second EAS systems for transmitting at least one unique signal into a partially overlapping interrogation zone of the EAS systems and for receiving any signals from the interrogation zones at respective and predetermined transmit and receive phases relative to a common reference. The first EAS system transmits at least one unique signal containing phase information which is received and identified at the second EAS system during one of its receiver phases as the one unique signal. The second EAS system uses the conveyed phase information received to transmit synchronously with transmissions from the first EAS system.

Abstract: An electronic article surveillance (EAS) system, comprising: an antenna for capturing signals generated in an interrogation zone, the captured signals including noise and, when at least one marker is present in the interrogation zone, a ring down signal with a characteristic frequency generated responsive to a magnetic field transmitted into the interrogation zone; a receiver having a signal processor for extracting amplitude and frequency information from the captured signals; and, a detector responsive to both the amplitude and frequency information for validating when the at least one marker is in the interrogation zone. The signal processor determines an average frequency of all markers in the interrogation zone, the detector being responsive to the average frequency. The signal processor can further determine successive frequency deviations of sequential frequency measurements and magnitudes of the deviations, the detector being responsive to the magnitudes of the deviations.

Abstract: A single antenna transmits and receives signals. The single antenna has first and second antenna loops substantially lying in a common plane and partially overlapping. First and second transceiver circuits are coupled to the first and second antenna loops respectively, for respectively generating in a first mode of operation first and second pulsed magnetic fields together defining an interrogation zone for a marker generating a characteristic response to the magnetic fields in the interrogation zone, and for receiving signals from the interrogation zone in a second mode of operation. The first and second transceiver circuits alternately generate the first and second magnetic fields substantially in phase with one another and substantially out of phase with one another. The partially overlapping antenna loops prevent detuning of the transceivers otherwise resulting from the phase alternating.

Abstract: A method for initializing an electronic article surveillance (EAS) system which transmits pulses into an interrogation zone and receives signals from the interrogation zone in a sequence of multiple successive transmit and receive windows during each line period of an AC mains supply energizing the EAS system, associated with a corresponding apparatus, comprises the steps of: (a.) determining whether a delay value is stored in a nonvolatile memory; (b.)if the delay value is stored in the nonvolatile memory, loading the stored delay value into a delay control register, terminating the initializing and omitting all remaining steps; (c.) if the delay value is not stored in the nonvolatile memory, loading a first delay value into the delay control register; (d.) determining whether noise in a certain receive window is less than a threshold level; (e.) if the noise is less than the threshold level, terminating the initializing and omitting all remaining steps; (f.

Abstract: An arrangement for improving the operation of an analog to digital converter (A/D), which can form part of an integrated circuit, the A/D converter being coupled to a reference voltage and having a plurality of input pins associated therewith comprises: a resistor divider having a plurality of resistors coupled in series, the resistor divider having an upper node coupled to a source of voltage to be converted, having a lower node coupled to a source of reference potential and having a plurality of intermediate nodes; and, each of the upper intermediate nodes being coupled to a respective one of the input pins of the A/D converter. The A/D converter can have enhanced resolution and/or an extended dynamic range when the voltage level being tested is divided arid the reference voltage is reduced.

Abstract: A method for adjusting a validation threshold for detecting a marker in an interrogation zone of an electronic surveillance system, comprising the steps of: (a.) tracking individual moving averages of background noise in a plurality of operational phase windows; (b.) tracking a moving variance for each of the moving averages of the background noise in each of the plurality of windows; and, (c.) continuously adjusting a validation threshold for detecting the marker in the interrogation zone responsive to the moving averages and responsive to the moving variances.

Abstract: An electronic article surveillance system has a receiver with a plurality of receiving coils. Each coil in the system is treated as a separate detection unit with its own noise environment which is distinct from the noise environments of the other coils in the system. The picture of the noise environment is preferably expanded to include examining noise per coil per phase. Control apparatus has facility for changing the interconnection and configuration of the receiving coils responsively to the per coil and per phase noise environment analysis. Noise analysis and coil configuration change can be practiced concurrently with EAS system operation or may be practiced during periods in which the EAS system is rendered inactive.

Abstract: An electronic article surveillance system has a receiver with a plurality of receiving coils. Each coil in the system is treated as a separate detection unit with its own noise environment which is distinct from the noise environments of the other coils in the system. This allows the system to optimize its performance by maximizing the sensitivity of each coil according to its own local noise environment. In EAS systems in accordance with the invention, the priority of the detection routines is to keep an accurate and up-to-date picture of the noise environment for each coil in "noise phases" and to look for tags during "transmit phases". Upon tag detection, a controller establishes a validation sequence comprising a number of cycles and can change the number of cycles adaptively to the noise environment.

Abstract: A deactivating device for deactivating a dual status EAS tag for use in an EAS system in which the device utilizes a detection field for detecting the presence of an active tag in a detection/deactivation zone and in which the device further utilizes a deactivation field which is matched to the detection field.

Abstract: A transmitter for an electronic article surveillance system having a power amplifier for forming a drive signal for causing a current to flow through an antenna. The magnitude of the current flowing through the antenna is sensed and, based upon the sensed current, the drive signal is continuously controlled.

Abstract: A magnetic article surveillance system utilizing microcomputer control and unique time domain and frequency domain information gathering channels whose information is processed by the microcomputer via preselected time domain and frequency domain criteria.