Abstract: In a method for transmitting a data message comprising a synchronization section and a data section stored in a transponder device (10) to an interrogating device (12) in full duplex mode. The interrogating device (12) continuously emits an interrogating command, the receipt of which in the transponder device (10) prompts output of the data message. Both the sync section and the data section of the data message each comprise a predetermined number of bits in accordance with a given transmission protocol. In the sync section, a predetermined number N of sequential bits of duration .tau. is replaced by a lesser number n of sequential bits of longer duration T, where: T=.tau. N/n. The interrogating device (12) determines the location of the sync section and thus the start of the data section in the received data message by identifying the bits having the longer duration T. For the ratio N/n a value is selected which is smaller than 1.5.

Abstract: A Radio Frequency Identification (RFID) system having an interrogator (12) and a transponder (14). The interrogator has a first tuned circuit (28) of a powering frequency for sending a powering burst to a transponder (14), a filter/demodulator (64) for receiving an wireless, modulated RF response from a transponder (14). The interrogator (12) further has a second tuned circuit (29) in electrical communication with a modulator (48), the second tuned circuit (29) having a selected bandwidth about a communication frequency, the selected bandwidth not substantially overlapping the powering frequency and encompassing the bandwidth of the modulated carrier of the RF response.

Abstract: A system, for bidirectional transmission of electromagnetic data signals between a stationary unit and a vehicle unit, in which at least two antennas can be used, is proposed. The antennas are aligned at a predetermined distance and at a predetermined height from one another, in such a way that reflection from the roadway and from vehicles is minimized. In the uplink mode, the antenna having the best reception properties is selected, so that reliable data transmission to the stationary unit takes place.

Abstract: A system and method for avoiding the discharge of a battery or otherwise excessive power consumption by a transponder (14) in the presence of a spurious noise source. In a described embodiment, the transponder (14) renders itself immune to activation by presence of RF energy for some period if the transponder does not receive a proper wake-up message within an activation period.

Abstract: This invention provides a tag identification system and method for identifying tags in the range of a reader station where the tags are divided into smaller groups, where the tags are identified one group at a time so as to save power by powering off the tags that are not in the group currently being identified. Each tag puts itself in a group by performing calculations from parameters stored in itself and from parameters received from the reader station. In another variation of this invention, only tags which configure themselves to be activated at a final frequency are identified. The set of tags which configure themselves to be activated at the final frequency changes with each identification round until all tags in the range of the reader have been identified.

Abstract: A dual frequency microwave EAS tag includes a dual frequency antenna circuit formed on one side of a substrate. The antenna circuit includes a diode. A deactivation circuit is formed on the other side of the substrate. A conductive connection passes through a hole in the substrate and connects the deactivation circuit to the antenna circuit. The deactivation circuit responds to a low energy ac magnetic field by inducing a voltage in the diode of the antenna circuit so as to disable the diode, thereby deactivating the tag without requiring the tag to be placed in direct contact with a disabling device.

Abstract: A radar sensor/processor for intelligent vehicle highway systems. The radar sensor/processor provides the range, speed, identity of, and selective communications with, vehicles equipped with a transponder in a first cooperative interrogator/transponder mode, and provides information on the range and speed of vehicles without a, or with an inoperative, transponder in a second noncooperative mode. The interrogator includes a first direct digital synthesizer, with an associated first input binary tune register, for producing a sine wave output, a multiplier for multiplying the sine wave output to produce an X-band signal, and a bi-phase single sideband modulator which modulates the X-band signal with data to be transmitted. The interrogator receiver receives a returned transponder reply signal, and includes a balanced mixer for downconverting the reply signal.

Abstract: There is described an electronic interrogation and identification (I/I) system in which an interrogator/reader (I/R) unit operates remotely using a microwave beam in conjunction with one or more coded articles. The articles are identified by a unique method and search sequence. As the I/R unit interrogates the articles, one or more of them respond to the I/R unit whenever a code word (data value) sent from the I/R unit matches a code word stored in one or more of the memory positions within the articles. After searching through all of the possible code words and word positions the I/R unit will have identified at least one code word stored in each of the word positions of at least one article. Then combinations of the just-identified code words are matched with the respective stored words of the various articles. After being uniquely identified each article is "powered-down" on command from the I/R unit and remains inactive so that one-by-one all remaining articles are also identified.

Abstract: A system and method for communicating between an identification reader 12 and a transponder unit 10 is disclosed herein. A first interrogation signal is transmitted from the reader 12. This first interrogation signal having a first read range. A first response signal is then received at the reader 12 after which a second interrogation signal is transmitted from the reader 12. The second interrogation signal has a second read range which is different than said first read range. The read range can be varied by varying either the amplitude or duration of the power level of the interrogation signal. A second response signal is then received at the reader 12. These consecutive responses are then compared determine a correct response signal which can be displayed.

Abstract: A protocol is used to coordinate the use of a common communication medium by one or more interrogating commander stations and an unknown plurality of responding responder stations. Each commander station and each responder station is equipped to broadcast messages and to check for error in received messages. When more than one station attempts to broadcast simultaneously, an erroneous message is received and communication is interrupted. To establish uninterrupted communication, a commander station broadcasts a command causing each responder station of a potentially large first number of responder stations to each select a random number from a known range and retain it as its arbitration number. After receipt of such a command, each addressed responder station transmits a response message containing its arbitration number. Zero, one, or several responses may occur simultaneously.

Abstract: The present application describes an electronically powered postage stamp or mailing label and including a radio frequency identification (RFID) device and system mounted between the opposing and facing major surfaces thereof. The RFID device and system includes an integrated circuit transceiver chip which is connected to and powered by a thin flat battery cell and is operated with a thin film RF antenna, all of which are mounted in side-by-side relationship on a thin base or support layer. These thin flat components are mounted in an essentially two dimensional planar configuration well suited for incorporation into the planar structure of a postage stamp or a mailing label. In addition, the RFID transceiver chip may be replaced with an electro-optically operated IC chip using, for example, LEDs or laser diodes for the propagation of light signals to an interrogator.

Abstract: An RF tag (20) includes a low profile battery power source (22). The RF tag includes an electrically insulating substrate 21, an RF transmitter (24) on the substrate for transmitting a predetermined identification code, and the battery (22). The battery includes a first pattern of conductive material to form a planar anode structure (48) and a second pattern of conductive material on the substrate to form a cathode structure (50). A protective layer (92) overlies the substrate. The protective layer includes an opening (94) to expose the anode and cathode of the battery to permit an electrolyte to be applied to the anode and cathode for completing the formation of the battery and to provide electrical energy to the RF transmitter. A manufacturing apparatus (60) is also described which permits the RF tags to be manufactured in a low cost, reel-to-reel, basis. Also described is a dispenser (100) for activating and dispensing the RF tags one at a time at a point of use.

Abstract: A method is disclosed herein for tuning a responder unit (12). The method comprises the stops of storing energy in a responder unit energy accumulator (136) in a contactless fashion by RF energy transmitted from the interrogator unit (10) to the responder unit (12), and exciting within the responder unit (12) an RF carrier wave. The method further comprises the stops of transmitting the RF carrier wave in a first response from the responder unit (12) to the interrogator unit (10) and measuring within the interrogator unit (10) the received signal strength of the RF carrier wave of the first response. In further accordance with the invention tuning data may be transmitted to the responder unit (12) by sending at least one RF programming sequence from the interrogator unit (10) to the responder unit (12).

Abstract: An apparatus including an object 10 associated with a contactless, electronic identifier is disclosed herein. In one example, the object 10 is a trash bin. This object 10 is formed from a non-conductive material. A single-loop antenna 14 is disposed adjacent the object 10. An impedance transformer 18 which is matched to the single-loop antenna 14 is used to generate a desired inductance. A transponder 12 is also disposed near to and associated with the object 10. The transponder 12 is coupled to the antenna 14 through the impedance transformer 18.

Abstract: A transponder interface circuit (172) operates to allow communication between a transponder controller (104) and external circuitry. The interface circuit (172) has a buffer memory (184,186) that allows the transponder controller (104) and the external circuitry each to transmit data at either the transponder's (14) or the external circuitry's clock rate without complicated protocols for direct communication. Each of the transponder controller (104) and the external circuit may be enabled by an interface controller (174) to assume control of the buffer memory (184,186). By using the buffer memory (184,186) and interface controller (174), whichever of the transponder controller (104) and the external circuitry is transmitting or receiving data may fill or empty the buffer memory (184,186) at either the transponder controller's (104) or the external circuitry's chosen clock rate.

Abstract: One or more roadside collection stations (RCS) communicate over a short-range, high speed bidirectional microwave communication link with one or more in-vehicle units (IVU) associated with one or more respectively corresponding vehicles in one or more traffic lanes of a highway. At least two up-link (IVU to RCS) communication sessions and at least one downlink (RCS to IVU) communication session are transacted in real time during the limited duration of an RCS communication footprint as the vehicle travels along its lane past a highway toll plaza. Especially efficient data formatting and processing is utilized so as to permit, during this brief interval, computation of the requisite toll amount and a fully verified and cryptographically secured (preferably anonymous) debiting of a smart card containing electronic money. Preferably an untraceable electronic check is communicated in a cryptographically sealed envelope with opener.

Abstract: The present invention relates to the areas of communication and/or identification of remote devices (active or passive). The invention has application where there is a need to identify or communicate with more than one remote device. The remote device may be embodied as a transmitter arrangement, transducer, transponder or responder. In particular, the present invention calls for each remote device to include a transmitter means in which, at each transmission, a carrier frequency or medium is newly selected.

Abstract: An transponder arrangement (10) for use with tires (20) is described. The arrangement (10) includes an antenna (14) which is mounted about the tire's (20) perimeter. The antenna (14) preferably has a coupling coil (16) at one end. A transponder (12) is preferably located close to the coupling coil (16) and is preferably loosely coupled to the coupling coil (16). The RF-ID efficiency of the arrangement (10) is generally optimized for this type of application by the long but narrow antenna solution and by the simple fact that coupling an antenna (14) to a transponder (12) amplifies the emission of the transponder's signal relative to the noise, thus improving the signal-to-noise ratio of the RF-ID system. The degree of coupling between the antenna (14) and the transponder (12) is not particularly critical. The antenna (14) acts to extend the reading range for the interrogator (24) to be generally, radially symmetric about the tire (20). Other arrangements are disclosed.

Abstract: A power supply self-contained within a portable RF/ID transponder includes a full wave rectifier having an input for receiving an antenna signal and outputs for providing power supply and ground voltages, wherein the power supply voltage has a time varying voltage waveform corresponding to the electric field generated by a reader/controller. The power supply further includes a clamping circuit for regulating the power supply voltage and a ferroelectric filter/storage capacitor coupled between the power supply and ground outputs of the full wave rectifier. The power supply further includes a power enable circuit for constantly monitoring the supply voltage waveform and for providing a power enable indication after an initial portion of the supply voltage waveform rises above a predetermined power-up threshold level and for removing the power enable indication when a terminal portion of the supply voltage waveform falls below a predetermined power-down level.

Abstract: A tagging system (20) compensates for both resonant frequency spatial dependent shifts and resonant frequency dependent shifts for detecting data resonant circuits (DC1-DC6) on an RF tag 10 which is carried by a tagged object (34). The system includes at least one transmitter (26) and at least one receiver (28) for determining the actual resonant frequencies of reference resonant circuits (SC1-SC5, FC1-FC4) on the tag 10. A microprocessor controller (22), in response to the frequency difference between the undisturbed resonant frequencies of the reference resonant circuits and the actual resonant frequencies of the reference resonant circuits, provides compensating factors to compensate for the spatial and frequency effects of the resonant frequencies of the resonant circuits on the tag (10). The transmitter and receiver determine the actual resonant frequency of each data resonant circuit (DC1-DC6) on the tag (10).

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 Passive Surface Acoustic Wave Identification Tag ("SAW-ID tag") device utilizes pulse compression techniques and a large number of coding possibilities for identifying articles at enhanced ranges. The SAW-ID tag device provides a piezoelectric substrate having bus bars, spaced electrode taps between the bus bars and a built-in antenna, with an input chirped SAW transducer having a dispersive, complementary matched filter response to an input expanded chirp signal from an expanded linear FM chirp waveform actively generated by a nearby chirp transmitter. The input expanded chirp signal is fed into the input chirped SAW transducer through the built-in antenna, to compresses the input expanded chirp signal into a narrow, compressed pulse signal propagating toward the electrodes taps. The spacing of the electrode taps establishes the desired unique time-ordered coding.

Abstract: A multi-interrogator transponder arrangement is disclosed. The transponder arrangement comprises a first interrogation unit (10) comprising a first wireless datacom transceiver (19) which transmits at least one RF interrogation signal. The arrangement also comprises a second interrogation unit (16) comprising a second wireless datacom transceiver which is in wireless communication with the first wireless datacom transceiver 19. The arrangement still further comprises a responder unit (12) which upon receipt of the RF interrogation signal transmits data stored therein back to the first interrogation unit 10 in the form of a responsive RF communication, the responder unit (12) comprising a responder unit energy accumulator (136) which stores energy contained in the RF interrogation signal. Other devices, systems and methods are also disclosed.

Abstract: A method of communicating between an interrogator (10) and at least a first and second transponder (12). The transponders (12)are separately located within a first and a second vehicle (20) travelling within a first and a second traffic lane, respectively. The method has the steps of providing a first and a second LF antenna (16) associated with and proximity to a first and a second traffic lane, respectively. From each of the first and second LF antennas (16) a continuous LF subcarrier is transmitted to serve as a clock signal for each antenna's associated transponder (12). Initially, a wake-up signal is sent by each of the LF antennas (16) to its associated transponder (12). Following the wake-up signal, a unique lane code is sent by each of the LF antennas (16) to its associated transponder (12). The transponder (12) stores its unique lane code in its memory (70).

Abstract: A transponder receives a stable reference frequency transmitted from an interrogator and compares the stable reference frequency to a local oscillator frequency that has short term stability. A comparison signal is provided to a synchronous oscillator for providing a locked signal that briefly locks onto the comparison signal and "remembers" its phase and frequency characteristics. The locked signal, which is inherently locked to the stable reference signal of the interrogator, is then combined with the short-term stable local oscillator frequency, and the combined signal is used in the up-converted reply back to the interrogator.

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.

Abstract: A self-tuning receiver/decoder for reception of FSK data transmission. An RF stage with resonant circuit (10) is tuned to a first of four possible transmitted frequencies for reception of such frequencies according to interrogation at such frequencies in sequence. Threshold (18) and counter circuits (12, 16) detect each frequency shift change of transmitted frequency and accordingly retune the resonant circuit to a subsequent unknown frequency by counting through a predetermined sequence for possible reception of each of such frequencies. Provision (24) is made for latching frequency shift data bit signals accordingly as output in a format identical to the frequency shift-keying RF format received. The receiver/decoder is especially useful for miniaturized transponder operation in which it alternates between receiving and transmitting modes, and is powered by capacitively stored charge in response to continuous transmission of the first frequency over a period.

Abstract: A transponder arrangement is described having an interrogator unit (10) which transmits at least one RF programming sequence and at least one RF interrogation pulse. The responder unit (12) includes a responder unit receiver (130) for receiving data transmitted by the RF programming sequence from the interrogator unit (10). The responder unit (12) then upon receipt of the RF interrogation pulse transmits data, which may have been modified by the programming sequence from the interrogator unit (10), back to the interrogator unit (10) in the form of a modulated RF carrier. The responder unit (12) further comprises a responder unit energy accumulator (136) which stores energy contained in the RF interrogation pulse and a responder unit end of burst detector (142) which upon detection of a decreasing power level of the RF interrogation pulse sends a RF threshold signal.

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: Disclosed is a system and method which protects a transponder or tag (14) from being enabled or awakened by spurious RF energy. A modulation detector (64) is provided which detects a modulation signal that is superimposed upon an RF modulation from an interrogator (12). Preferably this superimposed modulation is of a low frequency, below those typically existing as Electro-Magnetic Interference (EMI), such that the transponder (14) is less likely to be erroneously activated by an unintended RF signal. Upon reception of an RF interrogation having the proper modulation superimposed thereupon, the modulation detector (64) is operable to awaken other circuitry within the transponder (14) such that the transponder (14) is then operable to communicate with the interrogator (12).

Abstract: An interrogation unit which has a control circuit and an RF oscillator is described. The interrogation unit further has a transmitter which receives the output of the RF oscillator and transmits at least one RF interrogation pulse of a first frequency for interrogating the responder unit, causing the responder unit to return read data in the form of a RF response. Also in the interrogation unit is a switch for disabling the output of said transmitter and enabling reception of the RF response upon termination of the RF interrogation signal. The interrogation unit still further has a receiver for receiving the RF response upon termination of the RF interrogation pulse and an interrogation unit demodulator for demodulation of the read data from said RF response.

Abstract: A control circuit of a rader transponder produces pulses when the radar transponder detects a radio wave from a search radar. The pulses are sent to a sweep signal generator in which sawtooth waves are obtained through a first constant current circuit for linearizing the voltage-to-time characteristic in a falling portion of a sawtooth. The sweep signal generator further has a second constant current circuit for linearizing the voltage-to-time characteristic in a rising portion of a sawtooth.

Abstract: A responder unit for communicating with an interrogator unit which sends an RF interrogation pulse thereto is described. The responder unit includes an energy accumulator which stores the energy contained in the RF interrogation pulse to be used to power the responder unit in the absence of any RF interrogation signal. The responder unit also has a memory for storing read data and a RF threshold detector for detecting termination of the RF interrogation pulse. A RF carrier wave generator under control of the RF threshold detector is operable to activate upon detection of the termination of the RF interrogation pulse. A modulator is provided in the responder unit to modulate the RF carrier with the read data from the memory.

Abstract: A system and method for initiating communication between a controller and a selected one or other subset of multiple transponders in a common RF field in which each transponder has a unique, (or commonly unique) preprogrammed ID number. The controller transmits a series of commands/questions to the transponders and they either respond, or do not respond, to the controller based on their ID number, with the non-responding transponders entering a reset state. The transponders respond to the controller in such a way that, if multiple transponders respond, the controller can recognize that at least one transponder has responded and, for individual responses, the controller is not required to determine how many transponders have responded. Through use of the communications system and method disclosed, a sequence of controller commands and transponder responses single out a selected individual transponder or group of transponders based upon its particular ID number.

Abstract: A hardware and software solution for providing a tamper-proof, batteryless, remote transponder which will only be programmable by an authorized user is disclosed. This goal is achieved through the use of a hardware Cyclic Redundancy Check (CRC) generator which checks during a WRITE function of the data that is received from the Reading/Writing (R/W) unit and also generates several protection bits (Block Check Character; BCC) which are sent back during the response function (READ). Before the CRC generator checks the data during a WRITE function, however, it must be set to a predetermined start value called a Segment Code, and the Segment Code of the R/W unit must be the same as the Segment Code of the transponder in order for a Write (or a READ) to be performed. Additionally, programming of the Selective Address must be done within a predetermined time window (has a predetermined Time Code).

Abstract: The present invention provides a search and rescue radar transponder easy in maintenance and checking. In the search and rescue radar transponder of the invention, the transmission electric power of the transmitting circuit 3 leaked at the changeover switch 7 is inputted to the receiving circuit 2, and whether the search and rescue radar transponder operates normally or not is judged by comparing the leaked electric power level detected by the receiving circuit 2 with a prescribed level at the controlling circuit 4. Hereby, the operation-checking of the search and rescue radar transponder proper other than an antenna can be executed by a built-in apparatus, and its maintenance and checking can be executed easily and rapidly.

Abstract: A passive transponder includes a receive antenna for receiving an input signal. A frequency generator and modulator receives the input signal and outputs a data carrier signal having a frequency independent of the input signal frequency. A programmable memory and thermistor are provided to produce user ID data and temperature data which is combined with the output signal.

Abstract: An identification/security tag system, including miniaturized tags which can be readily concealed, utilizes a concept of "electronic" Doppler shifting to generate a frequency shifted signal in response to an interrogation signal. The frequency shifted signal is used to identify individual tags. The implementation of electronic Doppler shifting permits the utilization of conventional police/sport radar guns as a combined transmitter and receiver unit, thereby greatly reducing the expense of the system. The high frequency operation of the system permits size of the tag to be significantly reduced with respect to the size of tags used in conventional tag systems. Rectenna circuitry is further employed to eliminate the need for an active power supply in the tag in some applications.

Abstract: A device for information transmission, a so-called transponder, for receiving a first microwave signal, modulating and coding, and retransmitting a second microwave signal, having at least one antenna made in microstrip technique is described. The device is characterized primarily in that the antenna has an antenna layer (20), acting towards a ground plane (21), the antenna layer and the ground plane essentially equal area, and in that the device further having a reflex position (23 ), arranged next to or at a distance of at most 1/6 of the air wave length of the first microwave signal from the edges of the antenna layer and the ground plane, so that an antenna lobe directional from the antenna is obtained, including directly transmitted microwave signal and reflected microwave signal. With this embodiment a device is obtained that is compact, effective, light and inexpensive and gives well defined and directional antenna lobe for communications with good range.

Abstract: A method is disclosed herein for tuning a responder unit (12). The method comprises the steps of storing energy in a responder unit energy accumulator (136) in a contactless fashion by RF energy transmitted from the interrogator unit (10) to the responder unit (12), and exciting within the responder unit (12) an RF carrier wave. The method further comprises the steps of transmitting the RF carrier wave in a first response from the responder unit (12) to the interrogator unit (10) and measuring within the interrogator unit (10) the received signal strength of the RF carrier wave of the first response. In further accordance with the invention tuning data may be transmitted to the responder unit (12) by sending at least one RF programming sequence from the interrogator unit (10) to the responder unit (12).

Abstract: A system and method wherein a predetermined soft fuse value may be written to a corresponding soft fuse register to control subsequent access to a number of lock bits in a non-volatile semiconductor memory array which are provided for selectively precluding writes to predetermined portions of the memory array. In a specific embodiment, the system and method may be utilized in conjunction with radio frequency ("RF") identification ("ID") transponders incorporating a non-volatile ferroelectric random access memory ("FRAM") array integrated circuit.

Abstract: A device for positioning a first object relative to a second object, primarily for positioning an automatic fuelling device relative to vehicles. A transponder using a microstrip antenna design is small in dimension and gives accurate position indication by attachment to a back surface of a body which acts as a close reflection plane. The preferred embodiment of the device is a microstrip patch antenna where the ground plane is of similar size as the antenna element, and where the transponder is mounted on a car body rearward of the fuel filling point, to result in a radiation diagram that is created from the added direct signal from the antenna element and the reflected signal from the car body. A rounded profile of the transponder is a result of placement of its battery adjacent to the radiating element.

Abstract: A navigation system for a vehicle travelling along a highway that has an interrogator mounted on the vehicle and, a retrodirective transponder mounted alongside the highway for updating vehicle location. For collision avoidance systems, interrogators transmit and receive fore and aft, and transponders are mounted to respond to signals fore and aft of the vehicle. The transponder modulates information onto the interrogation signal, and retransmits the encoded interrogation signal back in the direction of arrival of the collected interrogation signal. The responder uses a Van Atta array antenna and is capable of responding to an interrogator signal incident over a wide solid angle of arrival while retrodirectively retransmitting without amplification substantially all of the collected signal within a narrow solid angle. The responder may be implemented using monolithic microwave integrated circuit technology (MMIC), thus being suitable for high volume production.

Abstract: A method for storing the life data of complicated products, primarily different types of automotive product, particularly cars, by the contactless transmission of information between a transmitter/receiver unit and a transponder. The transmitter/receiver unit includes one or more oscillators, transmitter and receiver antennas, a modulator and a detection circuit, and the transponder includes a transmitter/receiver antenna, a modulator and a detection circuit. The transponder is intended to accompany the product during its manufacture and to also accompany the finished product.

Abstract: A transponder (14) for communicating with an interrogator (12) has a high Q-factor resonant circuit (34) of frequency f.sub.1 for receiving RF powering signals. The transponder also has a tuning circuit (56,58) which when in electrical communication with the resonant circuit (34) is operable to form a lower Q-factor resonant circuit (60) of frequency f.sub.3 for receiving RF communications from the interrogator unit. The transponder also includes a demodulator (66) which is in electrical communication with said resonant circuit (34). Additionally, the transponder (14) also included a control circuit (40) which receives a demodulated data signal from the demodulator (66). The control circuit (40) is further connected to the tuning circuit (56,58) and is operable to connect the tuning circuit (56,58) to the high Q-factor resonant circuit (34) in order to form the lower Q-factor resonant circuit (60). Control circuit (40) also converts the RF powering signals to a DC current for storing energy.

Abstract: A microwave identification system comprising a transmitter/receiver provided with an antenna system, a plurality of responders provided with an antenna system, the communication between transmitter/receiver and responders taking place by means of electromagnetic waves in the microwave range, wherein the antenna system of the responders comprises an array with at least two antenna elements (12, 13) interconnected via a modulation device (14, 15, 16) and, for obtaining a retroreflective effect, the signal generated in an interrogation field by one of the two antenna elements is applied to the modulation device and, after being modulated with a code that is characteristic for the responder, is applied to the other antenna element to be radiated by the other antenna element.

Abstract: A method for the contactless transmission of information between a transmitter/receiver unit and a transponder.

Abstract: A method is described for reading the data stored in a passive responder (20) by means of an interrogation device (10) including a receiving section (14). To initiate a read cycle the interrogation device (10) transmits an HF interrogation pulse which on reception in the responder (20) is used to generate a supply voltage and initiates the transmission of an HF signal coded with the stored data. The frequency of the HF interrogation pulse is varied during its transmission over a predetermined range containing the nominal frequency of the responder (20). The receiving section (14) of the interrogation device (10) includes a tuning circuit (15) which adjusts the receiving frequency of the receiving section (14) to the frequency of the HF signal transmitted by the responder (20).

Abstract: A circuit arrangement is described with the aid of which a constant field strength of an HF signal radiated by a transmitting device (10) having an exchangeable antenna (12) can be achieved. Associated with the exchangeable antenna (12) is an antenna-specific component R1 from which in the operating state a control signal can be tapped after connection of the antenna (12) to the transmitting device (10). Said control signal is applied in the transmitting device (10) to an assembly (28) for influencing the transmitting power.

Abstract: A method of communicating between a transponder and an interrogator. The interrogator (10) transmits a wireless RF interrogation which is received by the transponder (12). The transponder (12) then transmits a wireless RF response. The wireless RF response has a first channel response centered at frequency FDX1=RF+SC, a second channel response centered at frequency FDX2=RF-SC, and a third channel response centered at frequency FDX3=SC. The third channel response is a spurious signal resulting from using a non-linear element (32) as the transponder modulator (32,34). The interrogator (10) receives this wireless RF response. The response is received in the three channels with a first circuit (82) operable to receive said first channel response, a second circuit (86) is operable to receive said second channel response, and a third circuit (86,88) is operable to receive said third channel response.