Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: In a pulsed-signal magnetomechanical electronic article surveillance system, a single transmit circuit is used to drive two or more parallel-connected interrogation signal transmitting antennas. One or more switchable damping circuits are provided in series with the antennas to promote rapid damping of the interrogation signal at the end of each signal pulse. The damping circuit or circuits are situated to provide damping in the loop or loops formed by the parallel-connected antennas. Each switchable damping circuit is formed of a resistance connected between a respective antenna and a terminal of the transmit circuit, as well as a switching element connected across the resistance. The switching element is maintained in a conducting condition during each signal pulse and is open-circuited at the end of each pulse to bring the resistance into effective damping connection with the transmit antennas.

Abstract: A transmitter circuit drives a transmit antenna for an electronic article surveillance system with an alternating drive signal. The transmitter circuit includes a DC power supply which converts an AC input power signal into a DC power supply potential, a switching circuit which forms an alternating signal from the DC power supply potential, and a transformer which couples the alternating signal to the antenna. The transformer provides isolation for the transmit antenna, as well as voltage step-down to a desired amplitude for the antenna driving signal. The DC potential supplied to the switching circuit may be regulated or unregulated.