Sensormatic Electronics Corporation

Tyco Fire + Security Gmbh

Jeffrey Thomas Oakes

Thomas James Frederick

Richard L Herring

Richard Loyd Copeland

Hubert A Patterson

Brent F Balch

Harry E Watkins

Richard B Frederick

Mart Martinson

Gerry Aguirre

A method for controlling electronic article surveillance (EAS) transmissions is described. The method includes calculating system parameters associated with one or more of a desired frequency a desired duty cycle, and a desired phase difference between antennas for a transmitter, and initializing a counter with a value based on the system parameters. The method also includes comparing a count from the counter to the system parameters, and modulating EAS transmission signals based on the comparison between the count and the system parameters. An EAS transmitter and an EAS system are also described.

Methods and apparatus for arbitrary antenna phasing in an electronic article surveillance system

Adaptive transmission of a tag activation signal and detection of a tag. By monitoring the effects of a load on a tag activation signal, a signal analyzer adjusts the transmission waveform from which the signal is generated so that the next tag activation signal transmitted into the load more closely corresponds to a desired activation signal.

Adaptively transmitting a signal for activating a tag

A system and method for providing wireless synchronized operation of electronic article surveillance (EAS) systems are provided. The method may include communicating wirelessly between each of a plurality of controllers connected to a plurality of detectors of the plurality of EAS systems and receiving with a communications receiver of each of the controllers wireless communications from at least some of the other plurality of controllers. The communications receiver may be separate from a tag detection receiver.

Wireless synchronized operation of pulsed EAS systems

A method for controlling electronic article surveillance (EAS) transmissions is described. The method includes calculating system parameters associated with one or more of a desired frequency, a desired duty cycle, and a desired phase difference between antennas for a transmitter, and initializing a counter with a value based on the system parameters. The method also includes comparing a count from the counter to the system parameters, and modulating EAS transmission signals based on the comparison between the count and the system parameters. An EAS transmitter and an EAS system are also described.

A method for controlling signal decay of a transmitted signal within a transmitter is described. The method includes measuring an amount of current induced back into the transmitter by the decaying signal, and using the current measurement to control the decay of the signal after the signal is transmitted from the load. A transmitter for an electronic article surveillance (EAS) system is also described which includes a current sensing circuit configured to at least sense an amount of current induced back into the transmitter by the load after transmission of the signal, and a transmitter control circuit configured to utilize the sensed current to determine an amount and a polarity of current to be applied to the load to reduce the induced current to a desired value.

Active transmitter ringdown for switching power amplifier

A method for controlling operation of a transmitter in an electronic article surveillance (EAS) system is described that includes coupling each of a plurality of transmit channels to a corresponding antenna, configuring a modulator within each transmit channel to output a modulated signal to the corresponding antenna, providing feedback of each modulated signal, and adjusting operation of each modulator based on the feedback. An EAS transmitter and an EAS system are also described.

Closed loop transmitter control for power amplifier in an EAS system

A distributed wireless phase locked loop system for synchronizing the transmit carrier's modulating waveform, such as the transmitter pulse timing in a pulsed EAS system and the transmit sweeping function for swept RF synchronization, is provided. To remove the effect of phase noise on the power line signal, a phase locked loop is used to filter this signal. The filtered output is used as a reference to a second phase locked loop tied to a numerically controlled oscillator and the received signal to provide a distributed phase looked loop algorithm that is wireless, and automatically synchronizes adjacent EAS systems.

Automatic wireless synchronization of electronic article surveillance systems

A ringdown canceller is provided for electronic article surveillance (EAS) tag response processing, which uses two adaptive replica signals and compares the replica signal phase to the receive signal phase to determine if there is a stationary EAS tag in the interrogation or detection zone. The adaptive replica buffers allow the system to adjust to changing ambient conditions, and adjust rapidly to an EAS tag that suddenly appears in the detection zone and becomes stationary, or to a stationary EAS tag that suddenly leaves the detection zone. The ringdown response of the transmitter circuit is constant, just like a stationary tag, and is removed from the receive signal in the same manner as a stationary tag.

Electronic article surveillance system stationary tag response canceller

In an EAS system and method, a reference antenna is used to spatially separate the interference and tag signal allowing the interference signal to be removed, which improves performance of the EAS receiver. The reference antenna is coupled to the system by an adaptive filter, which can be a software filter that is continually adapting itself to optimum performance. The continuous adaptation obviates the need for manually tuning the coupling network and permits the system to perform at its optimum level over long periods of time.

Large signal noise cancellation in electronic article surveillance

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.

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Boca Raton, FL, United States of America

Jeffrey Thomas Oakes