Abstract: A system and method for providing a fuel dispenser with radio frequency customer identification capabilities. The system and method determines whether a transponder containing customer identification data is within range of a dispenser, the dispenser requiring activation by the customer to initiate a transaction and including a reader associated therewith for emitting radio frequency signals within the dispenser range, and for receiving customer identification data from the transponder responsive to the emitted radio frequency signals received by the transponder. When the transponder is within range of the dispenser, an in-range indication is provided to the customer. A determination is made whether the dispenser has been activated by the customer following a determination that the transponder is within the dispenser range.

Abstract: A real-time location system for identifying and locating tagged items. The system may include an identification protocol that tracks in-network transponders and assigns dynamic in-network identification numbers to in-network transponders. The system includes a locator function that employs time-of-arrival analysis. Rather than attempt to synchronize the time base at each reader, the system and process eliminate the need to sync the readers and also eliminate the impact of differential receive delays in the respective readers. Both the transponder and a master reader transmit locate signals, which are measured at slave readers. The system relies on differences in time-of-arrival of the two signals at the respective slave readers to determine the likely location of the transponder.

Abstract: A system and method to facilitate drive-through ordering in which two or more options are presented to a customer and an in-vehicle transponder includes an input device to receive customer selection of one of the two or more options. The user selection received via the input device is relayed to the vendor through RF communications between the transponder and a reader.

Abstract: An RFID circuit comprises an RF carrier signal source, a hybrid coupled to the RF carrier signal source operable to generate an in-phase and a quadrature phase component of the RF carrier signal, a switch coupled to the hybrid operable to pass one of the in-phase and quadrature phase components of the RF carrier signal to its output, and a mixer coupled to the output of the switch operable to multiply one of the in-phase and quadrature phase component of the carrier signal and a received modulated carrier signal and generate a baseband signal.

Abstract: A method for use in a RFID reader, the method comprising providing an output signal from an amplifier of a transmitter, attenuating the output signal via a step attenuator, detecting and comparing the attenuated output signal to a reference value, and adjusting power to the amplifier until the attenuated output signal is substantially equal to the reference value. The attenuated output signal drives a local oscillator signal of a receiver thereby canceling noise generated by the transmitter in the receiver.

Abstract: An RFID reader, comprising a high-efficiency Class-C power amplifier having an input, an output, and a supply voltage, a modulator coupled to the supply voltage of the Class-C power amplifier, and an RF carrier signal coupled to the input of the Class-C power amplifier. The modulator changes the supply voltage of the Class-C power amplifier resulting in highly controlled amplitude modulation of the RF carrier signal at the output of the Class-C power amplifier.

Abstract: An antenna comprises a square patch element having first and second feed points and lying in a first plane, the first feed point being disposed near a first edge of the square patch element and substantially bisecting the first edge, and the second feed point being disposed near a second edge of the square patch element and substantially bisecting the second edge. The antenna further comprises a feed structure lying in a second plane parallel with the first plane and having a first segment coupled between a signal point and the first feed point, and a second segment coupled between the signal point and the second feed point, where the first and second segments of the feed structure have unequal lengths. The antenna further comprises a ground plane supporting the feed structure and square patch element.

Abstract: An RFID circuit comprising an RF carrier signal source, a hybrid coupled to the RF carrier signal source operable to generate first and second phase-shifted RF carrier signals, first and second mixers coupled to the hybrid each operable to multiply a respective one of the first and second carrier signals and a received backscattered modulated carrier signal and generate first and second baseband signals, respectively, and first logic coupled to the first and second mixers operable to select one of the first and second baseband signals having a larger amplitude as a demodulated RFID output signal.

Abstract: An RFID circuit comprises an RF carrier signal source, and a hybrid coupled thereto operable to generate first, second and third phase-shifted RF carrier signals. The circuit further comprises first, second, and third mixers coupled to the hybrid each operable to multiply one of the first, second and third respective carrier signals and a backscattered modulated carrier signal and generate first, second and third baseband signals, respectively. The circuit further comprises first, second, and third delay lines respectively coupled to the first, second, and third mixers and operable to generate first, second and third delayed baseband signals. The circuit further comprises logic coupled to the first, second, and third mixers and the first, second, and third delay lines and operable to detect substantially simultaneous data transitions in at least two of the first, second, and third baseband signals, and generating a reconstructed signal having a data transition in response thereto.

Abstract: An RFID circuit comprises an RF carrier signal source, a hybrid coupled to the RF carrier signal source operable to generate an in-phase and a quadrature phase component of the RF carrier signal, a switch coupled to the hybrid operable to pass one of the in-phase and quadrature phase components of the RF carrier signal to its output, and a mixer coupled to the output of the switch operable to multiply one of the in-phase and quadrature phase component of the carrier signal and a received modulated carrier signal and generate a baseband signal.

Abstract: A system of vehicle identification with a first interrogator that uses a Lower SideBand (LSB) receiver to receive a modulated signal from a vehicle transponder and a second interrogator that uses an Upper SideBand (USB) receiver to receive another modulated signal. The two interrogators are adjacent to each other at a toll plaza, and operate at different carrier frequencies to force a signal frequency bandgap between communication signals in adjacent vehicle lanes.

Abstract: A method of preventing a response to a rouge poll message in an AVI system is presented. The method entails that during the transmission of the poll message from the interrogator to the transponder, wherein the poll message reflects off an undesirable position, thereby creating the origination of an undesirable poll message, i.e. a poll message which will be received by a wrong transponder, a jamming signal is also transmitted at the same frequency and from the point from which said reflected poll message originates. The jamming signal and the poll message create a rogue poll message as received by the transponder wherein at least one bit within the transmitted poll message is flipped. Transponders, upon receiving said rogue poll message, calculate the CRC and compare the calculated CRC with the received CRC. The rogue message should yield an invalid CRC, i.e. a CRC unlike the received CRC, and therefore, the transponder will fail to respond to the jammed poll message.

Abstract: A lock (10) having inductive key detection includes a lock mechanism (14). A detector member (20) is movably disposed proximate the lock mechanism (14) such that the detector member (20) moves when a key engages the lock mechanism (14). The detector member (20) has a magnetic portion (24). An antenna (30) is disposed proximate the detector member (20) such that movement of the detector member (20) induces a signal in the antenna (30). A detector (42) is coupled to the antenna (30) and is operable to detect the signal in the antenna (30).

Abstract: The invention is an improved method and apparatus for synchronizing wireless communications utilizing a master source (10) for a transmitting a synchronizing pulse to multiple reader modules (20 and 28) each of which has an internal crystal oscillator (22 and 30). The synchronizing pulse periodically resets the interrogation cycle, the power burst and receive cycle, for all of the reader modules (20 and 28). Between pulses, the internal crystal oscillator (22 and 30) is used to run interrogation cycles, and thus functions as a "flywheel" to absorb fluctuations in the synchronizing pulse such as when a particular synchronizing pulse is missed.

Abstract: A key (10) is provided that includes a key body (12) having a forked end. The forked end comprises a first tine (14) and a second tine (16). A transponder (20) is disposed between the first tine (14) and the second tine (16). The transponder (20) is operable to generate signals. An air coil antenna (18) is coupled to the key body (12) proximate the forked end and is electrically coupled to the transponder (20). The air coil antenna (18) is operable to transmit signals generated by the transponder (20).

Abstract: Apparatus and method for producing a flexible antenna suitable to be incorporated in a badge or similar object. The antenna comprises electrical windings (28, 38) surrounding a flexible antenna core (26, 36). The antenna core (26, 36) is of a material having a high quality factor formed of a plurality of mutually insulated, longitudinally extending chains of magnetic soft material of high .mu.. According to one embodiment, a powder of small particles of a magnetic soft material of high .mu. is mixed with a synthetic resin so that a high saturation of magnetic material in the mixture is formed in a vacuum. The mixture is cured in a strong magnetic field so that the particles form chains (18A, 18B, 18C) of the particle parallel to the applied magnetic field.

Abstract: A balanced receive antenna circuit configuration determines an accurate position of a transponder within the antenna field pattern of the reader antenna. The balanced receive antenna configuration consists of two antennas physically rotated 90 degrees relative to one another, disposed concentrically on top of one another. Furthermore, each receive antenna consists of two coils located a predetermined distance apart. The optimum distance separating the coils is determined by trading off zero position detection with the transponder detection range. The transmitter antenna surrounds the receiver coilset. In operation, initially the transmitter antenna sends a power burst signal for a predetermined duration to charge up the transponder to the maximum charge possible. Then for a very brief duration, the transmitter antenna is damped to permit the receive antennas to better receive the transponder response telegram.

Abstract: A balanced receive antenna circuit configuration determines an accurate position of a transponder within the antenna field pattern of the reader antenna. The balanced receive antenna configuration consists of two antennas physically rotated 90 degrees relative to one another, disposed concentrically on top of one another. Furthermore, each receive antenna consists of two coils located a predetermined distance apart. The optimum distance separating the coils is determined by trading off zero position detection with the transponder detection range. A third receive reference antenna is concentrically disposed, sharing the same horizontal plane with the balanced antenna coilsets. The transmitter antenna is disposed separately from the receive antennas. In operation, initially the transmitter antenna sends a power burst signal for a predetermined duration to charge up the transponder to the maximum charge possible.

Abstract: This invention relates to a shielded transponder 12 which is capable of being mounted on any surface, whether ferromagnetic or not. The transponder includes an antenna which in use is susceptible to detuning as a result of being mounted on a ferromagnetic surface. The shield 16 prevents this detuning and enables the transponder 12 to be mounted on any surface. The shield 16 may produce slight detuning, however, this can be compensated for by pretuning of the transponder.

Abstract: A data detection circuit (30) for automatically adjusting to an FSK modulated signal to set a proper trip point for differentiating logic high and low. The detection circuit (30) includes: A demodulator (32) which converts a received FSK modulated signal to voltage levels corresponding to respective frequencies of the modulated signal. A voltage clamp circuit (42) which samples and stores a voltage level of the output of the demodulator (32) and provides a trip point voltage level representing a sum of the stored voltage level and a fixed voltage offset. A comparator (50) which compares the trip point voltage to the voltage levels at the output of the demodulator (32) to provide a logic output signal representing detected digital data signals.