Abstract: A device for data transmission in a motor vehicle and/or from a motor vehicle in its vicinity has a first transceiver unit (1) in or on the motor vehicle and a second transceiver unit (2) which is provided in at least one transponder unit whose spatial position relative to the vehicle may be variable or any desired position; it is characterized in that the first transceiver unit (1) is a radar unit equipped for distance measurement, expanded by adding a two-channel data transmission system; the second transceiver unit (2) is also a two-channel data transmission unit, and the microwave frequencies (f1, f2) for two-channel communication of the data transmission system are selected so that their difference |f1-f2| yields an intermediate frequency (fIF) which is processable using conventional components in a heterodyne receiver in the reception part of each of the first and second transceiver units (1, 2).

Abstract: A method and apparatus are provided that determine a frequency dependent calibration vector for a set of transmit or receive chains of a radio communications system using only differential phase and amplitude between the transmit chains and the receive chains, respectively. In one embodiment, the invention includes an antenna array adapted to transmit and receive radio communications signals with a plurality of other terminals, a transmit chain to transmit a calibration signal through the antenna array to a transponder on at least two different frequency bands, and a receive chain to receive through the antenna array a transponder signal from the transponder, the transponder signal being received on at least two different frequency bands and being based on the calibration signal.

Abstract: A computer generated pilot instruction system for providing spatial information to a pilot corresponding to the difference between the actual landing fight path and optimal landing flight path.

Abstract: SAW devices such as interdigital transducers (IDTs) have been widely used in RADAR applications and as filters. An IDT produces a SAW when excited by a single electrical pulse and can be fabricated to embody a code, which code provides for a passive autocorrelation of a SAW input to the IDT and thereby lends itself to further application as a signal generator in a communication device. However, conventional SAW expanders and compressors typically have insertion losses greater than 20 dB, which can have a profound effect on an RF link budget in a communication system. Insertion losses are drastically reduced by using a single phase unidirectional transducer (SPUDT-type) instead of a conventional IDT as a SAW expander/compressor. A SPUDT-type reflects SAW components which are lost in conventional IDT designs so that a stronger SAW is directed toward a transmission element. In a receiver, a SPUDT-type directs a stronger SAW toward a compressor IDT.

Abstract: An enhanced backscatter RF-ID tag reader system and multiprotocol RF tag reader system is provided. In a multiprotocol mode, the system emits a non-stationary interrogation signal, and decodes a phase modulated backscatter signal by detecting a stronger phase component from quadrature phase representations or determining phase transition edges in a phase of a received signal. The RF tag reader system predicts or follows the phase of the backscatter signal, thereby avoiding interference from nulls in the received signal waveform due to the non-stationary interrogation signal, relative movement or environmental effects. An acoustic RF-ID tag detection system detects the reradiated signal corresponding to respective transformation of a signal in the tag. Detection of either type of RF-DD tags therefore is possible, and the absence of any tag or absence of any valid tag also determined.

Abstract: A method, an apparatus and a computer program product are provided for accurately determining the vertical speed of an aircraft in a manner independent of signals provided by an air data computer, an inertial reference system and an inertial navigation system. Initially, a first vertical velocity of the aircraft is determined based upon a pressure altitude value associated with the aircraft. A second vertical velocity of the aircraft is also obtained from a GPS receiver carried by the aircraft. The first and second vertical velocities are then combined to determine the vertical speed of the aircraft. In this regard, the first and second vertical velocities are combined by complimentarily filtering the first and second vertical velocities. More particularly, the first vertical velocity is typically low pass filtered to remove high frequency noise that is attributable to the relatively low resolution of the first vertical velocity value.

Abstract: A road antenna apparatus includes a road antenna 104 which is mounted on a post 103 and at an elevated position on a road R and establishes radio communication with an on-vehicle radio device 102 mounted in a vehicle 101 which is traveling over the road; and a laser-beam emitting device 111 which is mounted on the road antenna and radiates a laser beam onto a predetermined position 113 on the surface of the road. An offset in the angle at which a road antenna is mounted can be readily ascertained on the basis of a distance between a predetermined position on the surface of the road and a position 114 on the road surface onto which a laser beam is actually radiated.

Abstract: The invention relates to a system suitable for a remote interrogation of passive transponders using chirp signals for interrogation. The transponder preferably has an encoding unit (11), a calibrating unit (12) and a measuring unit (13) each with a plurality of parallel channels (11.1 to 11.5, 12.1 and 13.1 to 13.2). The encoding unit and the calibrating unit are preferably jointly incorporated with a common delay line (14) on the same SAW chip. The interrogation signals received in the transponder via an antenna (10) are delayed characteristically and code-specifically, in particular in the encoding and calibrating unit. Decoding in the interrogation station is preformed by discrete Fourier transformation of the response signal and subsequent evaluation of the spectrum. To correct general disturbing influences on the delay of the response signal, said signal is calibrated using a single calibrating component in the response signal.

Abstract: A system and method for providing remote viewing of satellite transponder plots. The system and method piovides for remote viewing of transponder plots derived from transponders located on a satellite that communicate with ground terminals having an antenna. The system comprises an antenna switch for receiving transponder signals from the antenna. A spectrum analyzer is coupled to the antenna switch for generating transponder plots. An equipment control computer is coupled to the antenna switch and the spectrum analyzer that selectively routes signals from the antenna switch to the spectrum analyzer and routes transponder plots generated by the spectrum analyzer. A server computer is coupled to the equipment control computer that stores the transponder plots generated by the spectrum analyzer that are routed by the equipment control computer.

Abstract: A method of communicating to a RF tag having a low power mode and a scan mode with a radar and an interrogator. The method comprises the steps of alternating the RF tag between the low power mode and the scan mode and then transmitting a wake-up call to the RF tag with the radar. Next, the wake-up call is received from the radar by the RF tag when the RF tag is in the scan mode. Once the wake-up call has been received, the radar will transmit a downlink message to the RF tag. Upon receipt of the downlink message, the RF tag will send an uplinked message to the radar. After the uplink message has been sent to the radar, the RF tag will return to the low power mode. By alternating the RF tag between the low power mode and the scan mode, the power consumption of the RF tag is greatly reduced thereby increasing the battery life thereof.

Abstract: A method, an apparatus and a computer program product are provided for accurately determining the vertical speed of an aircraft in a manner independent of signals provided by an air data computer, an inertial reference system and an inertial navigation system. Initially, a first vertical velocity of the aircraft is determined based upon a pressure altitude value associated with the aircraft. A second vertical velocity of the aircraft is also obtained from a GPS receiver carried by the aircraft. The first and second vertical velocities are then combined to determine the vertical speed of the aircraft. In this regard, the first and second vertical velocities are combined by complimentarily filtering the first and second vertical velocities. More particularly, the first vertical velocity is typically low pass filtered to remove high frequency noise that is attributable to the relatively low resolution of the first vertical velocity value.

Abstract: A system for rapidly acquiring a time reference for the location determination of a wireless communication device. The system includes a wireless communication device (200), a GPS satellite (202) and a communication satellite (208). The method comprises the steps of acquiring a communication satellite signal (210) and using the finite frame time to establish a course time reference. Once the course time reference is established, an absolute device time is determined by the wireless communication device, which as a result is synchronized to the absolute time of the communication satellite (208) to within ten milliseconds. The absolute device time is then used to synchronize the GPS portion of the wireless communication device with the GPS satellite system.

Abstract: A transponder reading device and a control system for controlling the handling and/or processing of transponder-bearing objects by such transponder reading devices. The transponder reading device is equipped with its own microcontroller, and with its own control unit. The microcontroller is, as a component (node) of a control unit, able to communicate with other devices of the same design to exchange information. Consequently, several such devices can be operated simultaneously in a confined space without interfering with each other.

Abstract: A method of sending data from a base station to a passive RF tag and writing the data to a tag non-volatile memory which detects a “partial write”, where the tag voltage falls during the write process under the voltage sufficient to reliably write the tag non-volatile memory, is presented. The tag voltage is compared to a stable reference voltage during the time the tag memory is being written, and if the tag voltage falls below an acceptable level, a flag in the tag non-volatile memory is cleared.

Abstract: A method (200, 300) and apparatus (100) provides for displaying locally the position and identity of various field operatives or agents who have radio receiver transmitters (20, 30 and 40). A local control station (10) transmits a request for identification to radios (20, 30 and 40). Each radio responds back with a message (226) giving its location. The local control station then displays the identity and location of the unit on an area map (234) and stores the information in memory (236). Control station 10 further designates some or all of the radios (20, 30 and 40) with a laser designator signal (60). The radio then responds with an IFF signal (318) if it is a friendly agent.

Abstract: A method of forming a radio frequency communication apparatus includes providing a substrate provided with an outermost surface. An RFID is adhered at least partially within the substrate, and the RFID includes an antenna and an integrated circuit. The RFID and substrate together form a radio frequency communication apparatus. A method of forming a radio frequency communication apparatus includes providing a substrate with a frontside surface. An opening is formed through the frontside surface and into the substrate. An RFID is inserted within the opening and adhered to the substrate within the opening. The RFID includes an antenna and an integrated circuit to form a radio frequency communication apparatus.

Abstract: A method for increasing the accuracy of ranging measurements between data link systems is described. The method, actively aided ranging, increases ranging measurement accuracy by decreasing the dependence of the measurement on the relative clock bias between data links. The method is immune from error due to time bias between a position interrogator and a responder.

Abstract: In an automated roadway system having transponders or data-stations spaced at known positions along the roadway, a vehicle mounted system determines the position of a vehicle moving along the roadway. A vehicle borne transmitter transmits a spread spectrum transmit signal which is pseudo (PN) encoded. The transmitted signal is received by the transponder which emits a reply signal back to a vehicle borne receiver. The receiver also receives a second signal which may be a reply signal from the same transponder or a reply signal from an adjacent transponder. The system then measures a time difference between transmission of the vehicle originated interrogation signal and receipt of its corresponding reply signal to determine the distance between the vehicle and the transponder or reflector. Based on the determined distances, the positions of the transponders and the distance that the vehicle has traveled during its communications, the position of a vehicle is determined using triangulation methods.

Abstract: A method and apparatus are disclosed for making precise velocity measurements of a spacecraft using a two-way noncoherent Doppler tracking system. The received uplink and transmitted downlink frequencies on-board the spacecraft are compared with the resulting information being included in the downlink signal and used to cancel spacecraft oscillator drift rate effects in the two-way Doppler measurement made by the ground station. The information can also be used to characterize the drift rate of the spacecraft oscillator, thus permitting periods of accurate one-way Doppler tracking by the ground station. To improve accuracy, the times at which the measurements comprising the information would have been observed on the ground are inferred from the measurement of a signal generated by the spacecraft, e.g., the telemetry frame start times, made by the ground station.

Abstract: A customizable data acquisition device (DA) and a data collection system (DCS). The DA is remotely located for attachment to a variety of I/O devices, and uses an RF transceiver with a primary cache. A centrally located or mobile DCS with a secondary cache communicates with one or more DA's and stores DA data in the secondary cache. The DA has a programmable controller and an I/O interface capable of attaching to a variety of I/O devices. The DA primary cache holds data for bulk transfers to the DCS to minimize DA/DCS data transmission traffic. The DCS secondary cache accumulates data from the DA and allows data queries by multiple independent application programs (which may be located on the DCS, other DCSs, or remote host systems) without requiring retransmission of data from the DA for each query. Applications can query cached data in the secondary cache, and optionally query the primary cache or query the I/O device via the DA.

Abstract: An integrated circuit package assembly is disclosed herein and includes at least one integrated circuit chip having a plurality of chip input/output terminals, an arrangement for providing electrical communication between said input/output terminals and components external to said package, and an electrical inductor arrangement. The electrical inductor arrangement includes an origination terminal, a termination terminal, at least one intermediate connecting surface and a bonding wire positioned within the package. A first segment of the bonding wire is electrically connected with the origination terminal and a second segment is electrically connected with the termination terminal. Furthermore, the bonding wire has at least one intermediate point along it's length physically connected with one intermediate connecting surface. In one embodiment, the bonding wire is continuous along its length.

Abstract: A method and apparatus for sensing corrosion are provided in which an interrogation unit (14) transmits interrogation pulses and receives responses. A plurality of corrosion sensors (12) are disposed in the structure to be monitored (10), each of the sensors (12) generating an output. A plurality of responders (16) are powered from the interrogation pulses, one each of the responders (16) associated with one each of the sensors (12). The responders (16) are operable to transmit responses to the interrogation pulses based on the corrosion sensors' (12) output.

Abstract: A tire pressure sensing system is disclosed for detecting, transmitting and indicating low tire pressure information to a vehicle operator. One embodiment of the invention includes an improved pressure sensing switch comprising a hermetically sealed bladder and membrane switch. Another embodiment of the present invention includes an improved tire pressure sensing system which automatically communicates low tire pressure information as well as tire location information to the vehicle operator.

Abstract: A synchronous communication targeting system for use in battle. The present invention includes a transceiver having a stabilizing oscillator, a synchronous amplifier and an omnidirectional receiver, all in electrical communication with each other. A remotely located beacon is attached to a blackbody radiation source and has an amplitude modulator in electrical communication with a optical source. The beacon's amplitude modulator is set so that the optical source transmits radiation frequency at approximately the same or lower amplitude than that of the blackbody radiation source to which the beacon is attached. The receiver from the transceiver is adapted to receive frequencies approximately at or below blackbody radiation signals and sends such signals to the synchronous amplifier. The synchronous amplifier then rectifies and amplifies those signals which correspond to the predetermined frequency to therefore identify whether the blackbody radiation source is friendly or not.

Abstract: A method and apparatus are disclosed for making precise velocity measurements of a spacecraft using a two-way noncoherent Doppler tracking system. By comparing the received uplink and transmitted downlink frequencies on-board the spacecraft, information is generated that is included in the downlink signal and used to cancel spacecraft oscillator drift rate effects in the two-way Doppler measurement made by the ground station. This data can also be used to characterize the drift rate of the spacecraft oscillator, thus permitting periods of accurate one-way Doppler tracking by the ground station.

Abstract: A moving object identification system with a novel coding scheme achieves 75% transmission efficiency. With this system, a transmittable range is expanded. Logical value assignment for residual resonant oscillations in a residual resonant signal is performed by comparing a residual frequency with a threshold frequency. A wave energy reduction of an ASK modulated signal is used to decrease the energy of the signal in order to distinguish similar residual frequencies in the case of extremely close communication. Reliability of Write/Read instructions in this system is improved by employing a test writing before an actual writing and a voltage monitoring device.

Abstract: To provide a communications system to accurately detect when a mobile transceiver has entered an area where communication with a fixed transceiver is possible, and to start-up the internal circuitry of the mobile transceiver, a communications system transmits a start-up pilot signal of a prescribed period from a transponder mounted in a fixed station to a transponder mounted in a vehicle. In the transponder, the received signal upon being received by an antenna is detected in a detector and amplified in an amplifier. When this signal is greater than a reference voltage, a pulse is output from a level discriminator. This pulse signal is converted into a pulse of constant pulse width in a discriminator pulse generator and integrated in an integrator. When the integrated value exceeds a reference voltage, a start-up discriminator sends a drive signal to actuate the internal circuitry of the mobile transceiver.

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 system for communication by means of microwaves between transponders (3) and a central unit (5) is described. It is primarily characterized by a communication unit (4) for directed communication at a relatively short distance with the transponders (3) and at a relatively long distance with the central unit (5). The communication unit (4) also comprises a memory (23) for the intermediate storing of information.

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: 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 vehicle ID radar system has a simple construction and obtains high identifying performance by making a general identification based on a plurality of responses. There are provided an antenna for obtaining a plurality of question signals from a base station radar unit, a receiver for processing the signals received from the antenna, a question code demodulator for demodulating question codes from the received signals, a question code decoder for decoding the question codes and reading responses respectively corresponding to the plurality of questions from a plurality of data bases, a response code generator for generating response signals, and a transmitter for modulating the response signals and supplying them to the antenna.

Abstract: A method and apparatus for calibrating antenna array systems comprising of a portable transponder (118) and a calibration processor (124). Calibration processor (124) generates calibration transmit signals which it transmits using transmit signal processor (104) and antenna array (111). Transponder (118) echoes these signals back and they are acquired by calibration processor (124) through antenna array (111) and receive signal processor (106). Calibration processor (124) processes the received signals to calculate antenna calibration vector (102).

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: The monitoring assembly (10) monitors the location of mobile objects (12), i.e., personnel, within a structure (18). The object (12) carries a transponder (14) which periodically transmits status signals and receives command signals. Transceivers (16) are fixed at locations about the structure (18) for receiving the status signal producing the location signals, and transmitting commands to the transponders. The transmissions and reception occur during prescribed time windows. A central controller (20) is connected to each transceiver (16) and monitors the location of transponders (14) and communication therethrough. The transponders (14) have audio capability of producing audio messages directly to the person thereof, especially during emergency conditions for assistance. The controller (20) transmits synchronizing signals to the transceivers (16), which in turn synchronize themselves and transmit the synchronizing signal to the transponders (14) for synchronizing.

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 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: A self telemetry system for use on missiles that utilizes the existing on board fuze transmitter as a telemetry transmitter.

Abstract: A passive transponder incorporating non-volatile ferroelectric memory is powered by inductive coupling to a proximately located controller. A communication system and method utilizes the controller to send data and commands to the transponder by an FSK modulated RF signal in order to cause the transponder to either read selected data from, or write selected data to, the non-volatile memory and transmit the same back to the controller utilizing PSK RF modulation. The communication system and method operates either full duplex or half duplex with the controller causing the transponder to simultaneously write data to its non-volatile memory as the memory is read out and transmitted to the controller thereof. Features of the invention include, signal transmission between the controller and transponder occur concurrently; the controller's FSK signal is modulated between 125 KHz and 116.3 KHz; the transponder's PSK signal is 62.

Abstract: A passive RF transponder incorporating a non-volatile memory element is powered by inductive coupling to a proximately located RF controller. A communication system and method is disclosed which utilizes the controller to send data and commands to the transponder by means of an FSK modulated RF signal in order to cause the transponder to either read selected data from, or write selected data to, the non-volatile memory and transmit the same back to the controller utilizing PSK modulation. The communication system and method may be operated in either full duplex or half duplex modes of operation with the controller causing the transponder to simultaneously write data to its non-volatile memory array as the contents are read out and transmitted to the controller by complementing selected bits thereof.

Abstract: A transponder as well as a data communications system equipped with such a transponder are described, with which identification and/or individual addressing of the simultaneously present transponders is guaranteed in a simple manner even in the case of the simultaneous presence of a plurality of transponders in the field range of the reader.

Abstract: Doppler control circuit for a CW or pulse Doppler radar system for monitoring not only the phase shift between echo signals from several targets but also the amplitude difference between the several targets and to further provide a phase lock loop which tunes the radar to a particular target among one or more targets from which echo signals return. The control circuit can be used in state of the art CW or pulse Doppler type radar systems. In a further system, a continuously generated radar signal is repeatedly transmitted at three different frequencies in time division fashion to define a succession of transmit and receive frames. The receive frames are divided into a plurality of time interval windows with selected windows being used to detect received signals at the different frequencies. The remaining windows can be used for subsystems of the radar system.

Abstract: An interrogator-transponder system in which multiple vehicle mounted transponders which may be closely spaced in distance and moving at similar velocities are interrogated by interrogation signals that are identical for all interrogations. Digital coded data blocks consisting of an address code and a message code are transmitted on the interrogation frequency and are interleaved with the interrogation signals. Transponders respond with a coherent identification code and a message data code signal that is displaced in frequency from the interrogation signal by an amount that is identical for each transponder. The transponders decode interrogator data blocks that are associated with an address that is identical to the transponder identification code. The response signal spacings in time are difference for each transponder but are always multiples of the pulse repetition interval of the interrogation signal.

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: 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 low cost telemetry receiving system for use with an atmospheric sounding device includes an antenna configuration mounted on an azimuthally rotatable platform. The antennas have an asymmetrically shaped receiving beam having a narrow azimuth and wide elevation. The wide elevation is fixed due to a first antenna being oriented zenithally, and a second antenna being oriented horizonally. Rotating an azimuthally rotatable platform facilitates full canopy coverage for receiving telemetry. Determining when to reposition the rotatable platform is accomplished by sensing the strength of telemetry signal by rapidly sequencing the receiving beam so that it sweeps azimuthally within the narrow azimuthal view of the antenna. The platform rotates in the direction the signal is strongest.

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 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.