Abstract: A demodulator 5 is provided which may be constructed at low cost, can be integrated into current systems, and needs no external adjustments. The FSK demodulator 5 comprises a circuit 23 for generating an intermediate signal 101 as a function of high frequency intervals and low frequency intervals of an input FSK signal 100 and a circuit 24 for generating a demodulated output signal 102 as a function of the intermediate signal 101. According to one possible embodiment of the invention, an FSK signal 100 is demodulated by sending an FSK signal 100 through at least two retriggerable monostable multivibrators 23 and 24 each connected to an RC circuit 47 and 48 used to identify the high frequency and low frequency intervals of the input signal. The RC circuit components can be changed to accommodate FSK signals which use different frequencies for high and low input.

Abstract: A method of identifying an object and determining in which of at least two areas the object is located is disclosed. The method includes the steps of: focusing a first directional antenna (18) on a first area (28a), focusing a second directional antenna on a second area (28b), transmitting a first field strength pulse (44) from said first directional antenna (18), transmitting a second field strength pulse (46) from said second directional antenna (18), and comparing in a transponder (14) the first field strength pulse (44) to the second field strength pulse (46) to determine in which of the two areas (28a,28b) the transponder (14) is located. Other devices, systems and methods are also disclosed.

Abstract: A method and system is provided for communicating permanent or semi-permanent information to a transponder (14) from an interrogator (12), preferably operated by a toll agency or other authorized entity. This permanent or semi-permanent information is communicated by means of special instructions valid only during a special mode or maintenance mode which is entered by transmitting a special access code to the transponder (14) from the authorized interrogator (12). The transponder (14) will preferably acknowledge to the authorized interrogator (12) that it is, in fact, operating in the maintenance mode so the interrogator (12) can transmit the special instructions in confidence.

Abstract: A method of identifying an object and determining in which of at least two areas the object is located is disclosed. The method includes the steps of: focusing a first directional antenna (18) on a first area (28a), focusing a second directional antenna on a second area (28b), transmitting a first field strength pulse (44) from said first directional antenna (18), transmitting a second field strength pulse (46) from said second directional antenna (18), and comparing in a transponder (14) the first field strength pulse (44) to the second field strength pulse (46) to determine in which of the two areas (28a,28b) the transponder (14) is located. Other devices, systems and methods are also disclosed.

Abstract: A method is described with the aid of which messages can be transmitted from batteryless transponders to interrogation devices. The interrogation devices are equipped with a receiving section and a transmitting section and as a request to transmit the message stored therein as reaction to an interrogation command rendered effective in the interrogation device said devices transmit an HF interrogation pulse with predetermined carrier frequency and predetermined carrier duration. In the transponder this HF interrogation pulse is utilized to generate a supply voltage. Each interrogation device checks as reaction to an interrogation command whether its receiving section (14) is receiving a signal with the carrier frequency.

Abstract: An HF antenna comprising a sheet-like, flexible multipart magnet core (16) manufactured of ferromagnetic material is provided with an antenna winding which is made up of a plurality of turns and surrounds the magnet core (16). The turns of the antenna winding are formed by printed wiring (12a and 12b) arranged on a flexible film (10a and 10b) surrounding the magnet core (16).

Abstract: A method and apparatus with adaptive transponder plucking is provided in which oscillations from a resonant circuit (12 and 14) are maintained by coupling power from a capacitor (18) through a switch (26) to the resonant circuit (12 and 14). The switch (26) is controlled by adaptive pluck circuitry. The adaptive pluck circuitry includes peak level detector (22) and comparator (24). When the peak level of an oscillating signal from the resonant circuit (12 and 14) falls below a reference voltage, the switch (26) is activated to couple power to the resonant circuit (12 and 14).

Abstract: A system and method which conserves energy in the operation of a transponder or tag (14) by providing that the transponder (14) be enabled or awakened in multiple stages. A threshold detector (62) is provided which measures the power level of received RF energy. If the RF energy received by the detector (62) exceeds a pre-determined level, the transponder (14) then employs a modulation detector (64) to ascertain whether it has been awakened by a valid interrogation signal from an interrogator (12) or whether the RF energy received was merely a spurious burst of RF energy from some other source. If a pre-determined modulation is detected by the modulation detector (64), the transponder (14) is then fully activated to its normal operational state.

Abstract: A method of determining the exact location of a transponder with respect to a reader antenna, with no additional components to the existing system required, is disclosed. An existing pin of the reader IC, the RSTP pin, provides an analog fieldstrength signal from which the distance to the reader antenna is deduced via known in the art signal processing methods. A grid or even an exact position location along a route is also achievable with initial set-up of at least two transponders a predetermined distance apart and a reader antenna.

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 transponder device (10) includes a discharge circuit (18) to control the discharge of voltage from a charge capacitor (14). The discharge circuit (18) prevents transmission of a data telegram by the transponder device (10) until a voltage of the charge capacitor (14) reaches a threshold voltage level. The threshold voltage level is sufficient to ensure that a complete transmission of the data telegram is performed. Upon reaching the threshold voltage level, a transponder analog and digital circuit (19) initiates transmission of the data telegram. A control logic circuit (32) activates a counter (36) upon the start of the data telegram transmission. The counter (36) generates a control signal that is used to bypass the discharge circuit in order that the charge capacitor (14) can be connected directly to the transponder analog and digital circuit (19).

Abstract: Apparatus and method of identifying a plurality of transponders (10-16) entering into an inquiry field (18) of an interrogation unit (20) are provided. The transponders (10-16) are each assigned a unique identification code. Upon receipt of an interrogation pulse from the interrogation unit (20), each transponder (10-16) responds with its respective identification code. Depending on the spatial distance of each transponder (10-16) with respect to the interrogation unit (20), the interrogation unit (20) detects and receives the strongest response. The received identification code is stored. The interrogation unit (20) repeatedly sends interrogation pulses containing any stored identification code until all of the transponders (10-16) are identified and read.

Abstract: This invention allows a user to have a smartcard (66) and a smartcard-based transponder (14). This smartcard-based transponder (14) can accept money from the smartcard (14). The amount transferred from the smartcard (66) can be stored in the transponder memory (80,82). At a toll plaza (29), a toll amount can be subtracted within a short period of time, so that a vehicle (26) bearing the transponder (14) will not pass through the zone in which the transponder (14) and the interrogator (12) may perform RF communications before an appropriate toll amount can be decremented from the amount stored within the transponder (14).

Abstract: A thin and flat integrated circuit assembly (10, 40) may be achieved by using a thin carrier (20) with shallow cavities (22, 24) for holding the integrated circuits (16) and/or discrete circuit components (14). The integrated circuits (16) and/or circuit components (14) may be friction fitted in the cavities (22, 24) or they may be secured therein by the use of adhesives and/or solder. Electrical connection between the integrated circuits (16) and circuit components (14) may be done with wire bonding, ribbon bonding, tape-automated bonding, lead frames, flip chip bonding, and/or conductive gluing of leads. The circuit assembly may then be accommodated into a credit card-sized packaging with standard dimensions set by the International Standards Organization.

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: A method and apparatus for wireless supplying of chemicals is provided in which an interrogation unit (14) transmits interrogation signals. A responder unit (16), powered from the interrogation signals, is operable to receive the interrogation signals and transmit responses. The responder unit (16) controls operation of an actuator (10). The actuator is coupled to a supply tank (12), which supplies chemicals under control of the actuator (10).

Abstract: An arrangement for monitoring the operating state of vehicle pneumatic tires (14) mounted on wheel rims (10) is provided with sensors (40, 42) for detecting the air pressure and the air temperature in each tire. Furthermore, it includes transmitting means comprising rim-side mounted rotor members (28) and bodywork-side mounted stator members (32) coupled thereto for transmitting the parameters detected by the sensor (40, 42) to an evaluating arrangement in the vehicle connected to the stator members. The pressure sensor (40) and the temperature sensor (42) of each tire (14) are coupled to a first transponder (44) which as reaction to an interrogation signal generated by the evaluating arrangement transmits the data supplied to it by the pressure sensor (40) and the temperature sensor (42) to the rotor members (28) of the transmitting means.

Abstract: An alternative resonant circuit configuration reduces the amount of RF current that is switched by the power-stage transistors of a T/R unit and thereby also significantly reduces the reliability risk. A parallel resonant antenna configuration of coils and capacitors reduces the RF current through the output stage push-pull transistor configuration to a small fraction of the RF current experienced by typical series resonant circuits. This circuit offers advantages of low cost, reliable impedance matching while reducing the volume necessary to perform the function.

Abstract: An object of the invention is to provide a reader which can read transponders having different communication standard protocols with a minimum loss of demodulation speed performance and with the least amount of additional components.

Abstract: A transponder system comprises an interrogation unit for communicating with a plurality of responder units. At least one responder unit receives an interrogation signal from the interrogation unit and returns data as signal information to the interrogation unit in response to the reception of the interrogation signal. The responder unit also includes sensor circuitry sensitive to predetermined physical parameters in the environmental area of the responder unit and, via a data processor, generates data representative of the physical parameter and sends it back to the interrogator as signal information.