Abstract: Vehicle detector arrangement comprising at least one detector unit (8) comprising at least one sensor (47, 48, 49, 50), a transmission/reception unit (54), an energy supply unit and a control unit (51, 52, 53), whereby the energy supply unit comprises a solar cell module (3). The transmission/reception unit (54), the energy supply unit and the control unit (51, 52, 53) are accommodated in a housing (27, 28) and connected to the at least one detector unit (8), whereby the solar cell module (3) is secured to the outside of the housing (27, 28). As a result of what is thus autonomous functioning of the vehicle detector arrangement, it can be simply secured, for example, to a bridge (6), and complicated installation jobs for power supply and data transmission, for example to a traffic routing center, are avoided.

Abstract: A wire-loop vehicle detector is configured with a vertically oriented blade aligned at an angle to the direction of traffic-flow with each end of the blade extending laterally beyond the normal limits of vehicle presence over the blade. The extended blade configuration of the wire-loop constrains over-passing vehicles to present repeatable inductive signatures while electromagnetic noise and thermal-drift are selectively canceled using a secondary coil to increase the signal-to-noise ratio of inductance measurements. Inductive signatures of vehicles are recorded using a high-speed and high-precision method of making multiple successive measurements of the inductance of a wire-loop as vehicles pass over. Inductive signatures of automotive vehicles are useful for parking-lot revenue control, car-bomb detection, passive security of isolated communities, and other traffic-flow monitoring and control applications.

Abstract: A permanent in-pavement roadway traffic sensor for sensing roadway traffic comprising an extruded conductive elastomeric housing having an elongated cavity in the lower side thereof, said elongated cavity having an upper wall and a pair of spaced lower walls, a flat multiconductor ribbon Teflon™ cable having at least some of the conductors thereof spacedly mounted in the cavity from the upper wall. The flat multiconductor ribbon cable has a flat up side which is more effective for generating signals using residual charge-effect principles and the up side is positioned in the cavity facing the upper wall. The flat multiconductor ribbon cable has at least one lateral insulated conductor at the lateral sides thereof and the lateral insulated conductors abut the spaced lower walls, respectively. The elastomeric extrusion has sides which taper upwardly.

Abstract: Adding a quantity of metallic shot or particles of other materials having a high dielectric constant to the thermoplastic paint in the mixing pot of ordinary roadway marker fixation equipment, which extrudes the paint and applies same to the roadway surface, enhances the MMW radiometric visibility of the marker without adverse effect to the affixation equipment. Vehicles containing MMW radiometers directed down toward the roadway surface moves along the roadway surface is able to automatically sense microwave/millimeter wave energy from a marker in the vehicles path. In one system, the sensed energy is used in conjunction with other apparatus to assist to guide the vehicle within a traffic lane. In another system, the sensed energy is decoded and displayed as pertinent information for the vehicle's driver.

Abstract: A first magnetostrictive member 1a is housed in a storage section 2f of a first frame 2a and a second magnetostrictive member 1b is housed in a storage section 2g of a second frame 2b. They are fixed by an adhesive, etc., so as to sandwich a belt-like magnetic member 3 between the frames 2a and 2b. A sealing plate 4a, 4b is fixed to the opposite side of the frame 2a, 2b, forming a magnetostrictive resonator 5. When an electromagnetic wave is applied from the long side direction of the magnetostrictive member 1a, 1b, a magnetic field is applied to the magnetostrictive members 1a and 1b. When the frequency matches the resonance frequency of the magnetostrictive member, the magnetostrictive resonator 5 vibrates with the maximum amplitude. An electromagnetic wave emitted from the magnetostrictive member 1a or 1b can be detected based on mechanical vibration continuing for a short time still after the magnetic field is stopped.

Abstract: The invention relates to a device for low-frequency communication by magnetic coupling of the type comprising a magnetic field emitter and a receiver placed in an identification member, one of either the emitter or the receiver being furnished with a loop antenna, in which the other of either the emitter or the receiver is constituted by the association of three coils (1, 2, 3) wound around three perpendicular axes (Ox, Oy, Oz) defining a trihedral so as to obtain an omnidirectional magnetic field by supplying said coils with currents of like frequency.

Abstract: An apparatus and method for measuring the inductance of a wire-loop without direct reference to any particular time-constant or frequency. Low-frequency noise induced into the wire-loop is canceled within the detector circuit and crosstalk between a plurality of adjacent wire-loops is nullified using passive transformers. New wire-loop configurations utilize the permeability-modulated carrier referencing to provide repeatable inductive signatures with less intrusive, and non-intrusive installations.

Abstract: An apparatus of the invention includes a device for triggering a camera to photograph a vehicle within a traffic intersection, where the triggering of the camera is dependent on the speed of the vehicle before entering the intersection and may also be dependent on presence information. The device includes a sensor system (or “sensor array”) to transmit signals corresponding to a moving vehicle and a control system for processing the signals and triggering the camera. The signals preferably include “position signals” from which a transit time can be calculated, and “presence signals,” from which presence information can be obtained, particularly the location of the rear of the vehicle or the location of the rear wheels of the vehicle. A trigger time for taking a picture of the vehicle may be calculated from the transit time.

Abstract: An apparatus and method for measuring the inductance of a wire-loop without direct reference to any particular time-constant or frequency. Low-frequency noise induced into the wire-loop is canceled within the detector circuit and crosstalk between a plurality of adjacent wire-loops is nullified using passive transformers. New wire-loop configurations utilize the permeability-modulated carrier referencing to provide repeatable inductive signatures with less intrusive, and non-intrusive installations.

Abstract: An apparatus and method for measuring the inductance of a wire-loop without direct reference to any particular time-constant or frequency. Low-frequency noise induced into the wire-loop is canceled within the detector circuit and crosstalk between a plurality of adjacent wire-loops is nullified using passive transformers. New wire-loop configurations utilize the permeability-modulated carrier referencing to provide repeatable inductive signatures with less intrusive, and non-intrusive installations.

Abstract: Apparatus and method of evaluating and installing a wireless system, and is suited for a radio frequency identification (RFID) system. The apparatus determines the suitability of a particular site for use with specific RFID tag types. The apparatus comprises a tag evaluation module having a drobe, a wireless transmitter, and a processor. The probe is coupled to a tag under evaluation and information, such as tag power and data, is collected and stored by the processor. The information may be processed into logs which are transmitted to a computer for further processing. The tag evaluation apparatus may be utilized as a site survey tool before installation of a RFID system, or after installation as a diagnostic or performance optimizing tool.

Abstract: A road vehicle sensor provides an output signal having a magnitude which varies with time through a plurality of values as a vehicle passes the sensor. Signal processing apparatus monitors the timing of sensor signals generated from sensors in adjacent lanes of a highway and provides an indication when such sensor signals could correspond to a double count with a single vehicle being detected by both sensors. Then, the geometric mean of the amplitudes of the sensor signals from the sensors in adjacent lanes is calculated and is used to indicate a double count if the geometric mean is below a threshold value. Signal processing arrangements are also described to detect tailgating vehicles which may be simultaneously detected by a sensor, and for determining the length of slow moving or stationary traffic.

Abstract: A system and method for measuring a plurality of successive induction measurements, collectively known as the “inductive signature” of a vehicle, and classifying the vehicle described by the measured inductive signature. The system includes a blade-type wire-loop configuration, or blade sensor and a corresponding measurement circuit employing a discrete measurement technique, as opposed to the frequency counting technique of the prior art. The system and method produce repeatable inductive signatures at a high resolution that allows for accurate identification and classification of a vehicle.

Abstract: An oscillator circuit for use with a wire-loop inductive sensor and method for use. The oscillator circuit includes two balanced capacitors coupled to the wire-loop sensor, and an excitation circuit connectable with the capacitors at a selected polarity. Wherein, when the excitation circuit is connected to the capacitors, one of the capacitors is charged while the other capacitor is discharged, and both of the capacitors are discharged when the excitation circuit is disconnected to produce a pair of decaying oscillations having a caduceus-shaped output. The oscillator circuit highly attenuates common-mode noise detected by the wire-loop and differential noise from both ambient and crosstalk sources is filtered by active isolation.

Abstract: An inductive loop sensor for detecting vehicles travelling along a lane of a roadway comprises a figure-of-eight conducting loop. The loop is arranged with its three segments transversely across the roadway to detect the wheels of vehicles travelling along the roadway. The length of the loop in the direction of travel along the roadway is less than 60 cms. Traffic monitoring apparatus energises the loops and detects the passage of vehicle wheels over the loops to provide for the classification of vehicles by axle count.

Abstract: An inductive loop sensor for detecting vehicles travelling along a lane of a roadway comprises a figure-of-eight conducting loop. The loop is arranged with its three segments transversely across the roadway to detect the wheels of vehicles travelling along the roadway. The length of the loop in the direction of travel along the roadway is less than 60 cms. Traffic monitoring apparatus energises the loops and detects the passage of vehicle wheels over the loops to provide for the classification of vehicles by axle count.

Abstract: A vehicular roadway sensor comprising a conductive elastomeric housing having a sensor wire groove and one or more signal wire in the sensor wire groove, the sensor wire groove comprised of an airgap portion and a sensing wire portion for receiving and maintaining one or more insulated sensing wires in a fixed relation to establish a residual charge relationship with the conductive elastomeric housing so that when the fixed relationship is changed by the wheels of a vehicle on the housing a signal voltage is induced in the sensor, and one or more insulated signal carrying conductors connected to the one or more sensor wires, respectively. The one or more insulated signal carrying conductors are adhesively mounted in the conductive elastomeric housing so that vehicular traffic traversing the conductive elastomeric housing does not induce significant signals in the one or more insulated signal carrying conductors.

Abstract: An oscillator circuit for use with a wire-loop inductive sensor and method for use. The oscillator circuit highly attenuates common-mode noise detected by the wire-loop and differential noise from both ambient and crosstalk sources are filtered by active isolation.

Abstract: A traffic recording system for recording vehicular traffic events on a roadway having one or more lanes of traffic has a power control unit and a timer counter. Multilane roadway sensors sense roadway traffic and generates analog signals for vehicles traversing the traffic lanes. Each lane has a lane circuit having a sensor amplifier for processing incoming analog signals and converting the analog signals to digital square wave signal with fast rise time, a latch circuit connected to the sensor amplifier for latching sensor amplifier data. A data storage unit has removable data storage media, such as flashcards. A second latch circuit is connected to the timer counter, and a timing and power control logic circuit connected to receive signals from the sensor amplifier.

Abstract: A passive magnetic detector is provided at ground level or buried below ground level in between rails of a railroad track at a distance from the level crossing for detecting magnetic field disturbances caused by ferromagnetic objects passing overhead on the track. Magnetic field reversals are detected in the passive detector signal. The reversal signal is analyzed and a train presence output signal is generated for controlling a level crossing gate system or other such crossing warning system. For parallel tracks, pairs of passive magnetic field detectors detect objects over each track and the reversals are analyzed to check that an inbound train does not sneak by undetected as an outbound train is leaving and passing over the same detector pair. At the level crossing, static magnetic field detectors are used to ensure that no equipment remains on the island after detecting that the moving train has left the crossing, so that the crossing gates can be safely lifted as soon as possible.

Abstract: A method and apparatus for visually and audibly verifying Call signal generation in a vehicle detector. A generated Call signal drives a visible display, such as a discrete LED, an LED display composed of multiple discrete LEDs, or an LCD display. The same generated Call signal also controls the operation of an audible tone generator so that an audible tone is generated whenever the vehicle detector generates a Call signal.

Abstract: First and second loop coils are located at respective positions separate from each other by a predetermined distance. A first electric signal is generated which depends on an inductance of the first loop coil. A second electric signal is generated which depends on an inductance of the second loop coil. Detection is made as to a speed of a vehicle, which passes through first and second given regions determined by the respective positions of the first and second loop coils, in response to the first and second electric signals. The first electric signal is compared with a reference signal to decide whether or not a vehicle passes through the first given region determined by the position of the first loop coil. The reference signal is controlled in response to conditions of the first electric signal which occur in a follow-up time. The follow-up time is changed in response to the detected vehicle speed.

Abstract: An automatic fueling system containing a fueling machine having a nozzle mechanism comprising an injection pipe with a nozzle insertion sensor thereon, and a plurality of fueling nozzles contained in the injection pipe, each for dispensing a predetermined sort of fuel, and a fuel port sensor; and a data input/output unit for performing a signal transmission to and from the fueling machine; wherein the insertion of one of the nozzles is carried out to an automobile to be fueled having a signal generator thereon by the movement of the fueling machine based on the signal transmission between the fuel port sensor and the signal generator, and the fueling is suspended by the detection of a required level of fueling.

Abstract: A device for monitoring the passage of a train traveling through a rail way crossing, said device including a first and second sensors for sensing the presence of the train on a rail track when the train is in proximity to the sensors, said first and second sensors positioned adjacent the track, first and second processors opperatively coupled to the first and second sensors, respectively, the processors adapted to monitor the sensors and determine the speed and direction of the train when the train passes the sensors. The device also includes a signal positioned adjacent the crossing for signaling the public that a train is about to enter the rail way crossing, and a third processor operatively coupled to the signal and operatively coupled to the first and second processors, the third processor adapted to activate the signal when the train is within a predetermined time interval from entering the crossing.

Abstract: An improved detector is provided for installation in a roadway surface. The detector finds utility in a highway vehicle detection system for determining vehicle presence, vehicle speed and vehicle length. First and second matched induction coil magnetic sensors are maintained at or near the roadway surface. Each of the sensors has a longitudinal axis aligned normal to the roadway surface. The first and second sensors are separated from one another by a known distance in a direction substantially aligned with a direction of traffic flow. Each of the sensors generate a differential magnetic field signature with respect to time to indicate a passing vehicle's leading and trailing edge magnetic signatures. Vehicle speed is determined by a time-distance relationship using the leading and trailing edge magnetic signatures and the known distance. Vehicle length is determined by a time-speed relationship using the leading and trailing edge magnetic signatures and the determined vehicle speed.

Abstract: A driveway alarm system for disposing along a driveway of a home or business for warning an occupant of the premise about an object, including a vehicle, on the driveway, or for warning a driver of a vehicle about an overhanging object in the driveway. The overhead warning and driveway alarm system includes a solar panel, a battery, a magnetic field generator, a driveway probe and a transmitter. The solar panel charges the battery which powers the driveway probe and the transmitter. The driveway probe creates a magnetic field. When the magnetic field is disturbed, the transmitter is activated, sending a radio signal to the receiver. In operation, when a car or other object disturbs the magnetic field proximate the driveway probe sensor, the transmitter provides a radio alert signal to the indoor subsystem.

Abstract: With this device for positioning motor vehicles (F) in front of vehicle washing plants, especially portal washing plants, at least one transmitting-/receiving device (5, 6) in the portal is assigned to each terminating plane (E1, E2), which portal has a clear space of a predetermined clearance width (D), which clear space is delimited laterally by imaginary, substantially vertical terminating planes (E1, E2) extending in the direction of movement. Said transmitting-/receiving device emits signals, which extend substantially in the terminating plane (E1, E2) in the space in front of the portal (1), and receives said signals.

Abstract: A residual charge traffic sensor for monitoring the number and speed of vehicles traveling in multiple lanes of a roadway includes a housing containing a cavity, a conductive mounting bar adapted to fit within the cavity, at least two sensing elements mounted on the mounting bar which generate a signal when impacted by a vehicle tire, a transmission cable connected with the sensing elements for transmitting the electric signals generated by the sensing elements, and analyzing equipment for evaluating, displaying, and recording the data generated by the sensing elements. Signals are transmitted through every other wire of the transmission cable to minimize cross-talk between the signal carrying wires.

Abstract: An apparatus of the invention includes a device for triggering a camera to photograph a vehicle within a traffic intersection, where the triggering of the camera is dependent on the speed of the vehicle before entering the intersection and may also be dependent on presence information. The device includes a sensor system (or "sensor array") to transmit signals corresponding to a moving vehicle and a control system for processing the signals and triggering the camera. The signals preferably include "position signals" from which a transit time can be calculated, and "presence signals," from which presence information can be obtained, particularly the location of the rear of the vehicle or the location of the rear wheels of the vehicle. A trigger time for taking a picture of the vehicle may be calculated from the transit time.

Abstract: A system and method of registering vehicles in a road toll facility is provided with radio transmitter and receiver equipment (7) for microwaves arranged to communicate with vehicle units (12) provided in the vehicles (4), preferably including a transponder. On command from the road toll facility, an identity is obtained from the in-vehicle unit and a toll debiting operation is performed. When a vehicle (4) enters the toll facility, it is detected via the activation of the toll facility radio equipment (7) if the vehicle (4) is provided with a vehicle unit (12) and if it has performed a correct payment operation. Vehicles for which such operations cannot take place are exposed to a successive position determination via video cameras (9) through an image processing in which the vehicle in question is tracked between a predetermined recording site and the location where the payment status of the vehicle has been established via the radio equipment.

Abstract: A vehicle detectors with at least one inductive loop is used as a sensor. An oscillator circuit comprises a fixed-frequency oscillator, which is directly connected to one of the inductive loops' two terminals, for purposes of exciting said loop. In addition, a phase/amplitude controller is arranged between the fixed-frequency oscillator and the other terminal, which forms a summation point of the inductive loop to deliver a compensation signal that is derived from the transmit signal in an amplitude-controlled and phase-controlled manner. The inductive loop, the fixed-frequency oscillator and the phase/amplitude controller form a bridge circuit in which (with reference to the resulting voltage at the summation point) the transmit signal and the compensation signal add up to zero in the resting state of the inductive loop. A detection signal for the presence of a vehicle in the detection range of the induction loop is derived from a voltage at this summation point which deviates therefrom.

Abstract: A magnetostrictive resonator detection apparatus includes a transmission section for transmitting a resonance frequency of a magnetostrictive resonator, and a reception section for detecting a resonance frequency oscillated by the magnetostrictive resonator.

Abstract: A method and system for controlling the movement of one or more automatic guided vehicles includes a system controller, a number of non-wire automatic guided vehicles (AGV's) and location markers positioned on a floor. The system controller serves as a dispatcher and traffic controller for the system, providing, in one embodiment, two way wireless communication to each AGV in the system. Each AGV is equipped with a navigation and guidance system for controlling the AGV's movement along a predefined guidepath. Differential X, Y-coordinates from a path point database stored in the system controller are communicated to a given AGV which can then follow the predefined guidepath. Communicating just the differential X, Y-coordinates allows for improved control over systems utilizing a large number of AGV's.

Abstract: A programmable vehicle detector with operator actuatable function selection and parameter value setting keys, and an operational display. A small cluster (four) of key switches enables an operator to select programmable vehicle detector functions, such as pulse/presence, scanning/non-scanning, end of green control; and also adjust the value of settable parameters, such as loop frequency, sensitivity, delay time, and maximum presence time. The value of certain parameters is displayed, either by manual interrogation by operation of the switches during a set mode or automatically during normal operation. During normal operation, the display also indicates dynamically the relative value of the loop inductance, using a unique bar graph, the generation of Call a signal, and the time remaining in a delay time period and a maximum presence time period. The display further indicates which of several channels has been selected for function and parameter programming, or is currently being monitored for operation.

Abstract: A directional traffic sensing system and method employing one or more pairs of overlapping sensor loops, a sensing controller driving the sensor loops, interference minimization between the overlapping loops, direction of travel determination, and reduction of false directional reports.

Abstract: In a first embodiment, a voltage controlled oscillator (VCO) is driven by a generator that provides a cyclic voltage having a sawtooth waveform. The VCO cyclicly provides a signal at a frequency that varies over a range that includes a frequency of a transmitted signal that causes a vehicular traffic signal light control system, of a type that has an inductive loop buried in a roadway, to provide a desired illumination of traffic signal lights of the system. The VCO is connected to a power amplifier that has its output connected to an antenna. In a second embodiment, a signal processor provides a train of pulses at a frequency of radiation from the inductive loop. The number of the pulses of the pulse train that are provided during a timing interval is stored by a counter. A digital to analog converter is connected to the output of the counter. After the timing interval, a signal is transmitted substantially at the frequency of radiation in response to the output of a VCO that is connected to the converter.

Abstract: A mobile unit support system comprises at least one magnetic member for forming a magnetic field in said vicinity of a movement path of a mobile unit which is made of a dielectromagnetic material; and at least one magnetic sensor which, when said mobile unit passes over, detects a change of said magnetic field and which transmits a result of said detection to an external, and said mobile unit comprises receiving means for receiving said transmitted signal, and a processing section which processes a signal from said receiving means.

Abstract: A system for passively sensing low frequency (5 Hz to 50 kHz) EM emanations from vehicles and classifying them on that basis. A temporal frequency response is computed for the sensed EM emanations. Harmonic, non-harmonic and temporal features are extracted from the response and used to classify the vehicle. In the preferred embodiment, the temporal frequency response is displayed as a time, frequency and intensity plot, from which a technician visually extracts these features. The features can then be used either to determine a "signature" for classifying the vehicle or to determine specific characteristics which, in turn, can be used to classify the vehicle. Alternately, the feature extraction and classification can be performed by an automated classifier.

Abstract: A communication system for a plurality of carriages that travel along a rail. A power cable extends along the rail. The cable is used to convey electric current that drives the movable bodies and is also used to carry information between the carriages. The carriages communicate with one another by superimposing communication signals on the current flowing through the cable to transmit information and by extracting communication signals from the current flowing through the cable to receive information. A control unit at a fixed station relays communication signals transmitted between different carriages. The control unit receives communication signals, which the carriages transmit, from the cable, amplifies the signals, and returns the signals to the cable. The recipient carriage receives an amplified communication signal from the cable.

Abstract: A passive remote garage door operator system including a magnetic field sensor which detects a magnet having a flux density and a transmitter that sends a coded security signal to activate a garage door. A controller determines whether the magnet field sensor detects the magnet from a first direction or a second direction and activates the position of the garage door. The magnetic field sensor is preferably affixed to the underside of a vehicle and the magnets are embedded in a driveway leading to the garage. The system thereby automatically opens a garage door based upon the approach of a vehicle and closes automatically based upon the exit of the vehicle without any intervention by the human vehicle operator.

Abstract: A vehicle detector with improved reference tracking routines in both the Call direction and the No Call direction. Call direction tracking includes rate sensitive tracking in which the reference is only changed in response to small fluctuations in loop frequency due to drift, and one or more fixed decrementing tracking intervals during which the reference is decremented at a fixed rate for a maximum predetermined period of time. Call direction tracking also includes infinite tracking during which the reference is decremented to an end value representative of loop inductance prior to the generation of a call signal. No Call tracking permits reference updating only after the loop frequency has stabilized for a minimum period of time, a minimum number of loop frequency samples or both.

Abstract: On the moving body, the apparatus comprises an active transponder, and on the track it comprises a passive responder. The transponder has an LF transmitter and an MF transmitter which, during displacement of the moving body, transmit to a zone through which the responder passes during said displacement. The responder has an LF receiver circuit and an MF receiver circuit having tuned radiating circuits that are associated so that an LF signal induced in the LF circuit causes the MF radiating circuit of the responder to be closed at the LF rate. The transponder responds to disturbances in the MF transmitter caused by the MF circuit of the responder being closed. The MF circuit of the responder includes two units having respective tuned radiating circuits that are strongly coupled together. Each is connected to a respective logic unit which, when excited, delivers a digital message causing the MF radiating circuit to be closed only for bits of a determined value in the digital message.

Abstract: A vehicle position recognition apparatus comprising one or a plurality of magnetic field formation means 1-1 installed at predetermined positions on a road for forming a predetermined magnetic field, magnetic field strength detection means 1-4 for detecting the magnetic field formed by the magnetic field formation means 1-1, vehicle position computation suitability judgment means 1-5 for judging whether the magnetic field strength, obtained by the magnetic field detection means 1-4, is suitable or not for computing a position of the vehicle, and vehicle position computation means 1-6 for receiving a result of the judgment of the vehicle position computation suitability judgment means 1-5 and for detecting the position of the vehicle by the magnetic field strength detected by the magnetic field strength detection means 1-4.

Abstract: A system for detecting an object located on a travelling path even in bad weather or during nighttime in which conducting wires having a predetermined impedance value are laid along a travelling path, and a signal is supplied to the conducting wires from a signal source. If a vehicle exists on the path, the impedance of the conducting wires changes at the position where the vehicle is present. A signal reflected from the impedance change position is detected by a detector. The position of the vehicle can be determined from the timing of the received reflection signal. It is also possible to detect a vehicle changing lanes or the like by means of a plurality of conductive wires laid along the travelling path. Instead of a conducting wire, an optical fiber may be provided for determining the position of a vehicle using the refractive index change in the optical fiber due to the weight of the vehicle.

Abstract: A vehicle detector comprising a flux gate magnetometer with vertical and horizontal sensing coils is positioned within a roadway. The ambient levels of the earth's magnetic field as sensed by the magnetometer are used to establish reference levels and deviations therefrom are evaluated by a microprocessor which produces a vehicle arrived signal when the vertical component of sensed perturbations exceed a threshold and in an alternate mode when either vertical or horizontal levels exceed threshold values. Both vertical and horizontal levels must fall below threshold levels to determine a departure in either mode. Vehicle arrival and departure events are encoded as NRZ data packets which are transmitted by an edge-fired antenna as FM modulated signals. A remote multi-channel receiver capable of responding to a plurality of magnetometer modulated FM transmitters processes the received data and provides signals that are used by traffic signal controlling computers.

Abstract: The apparatus is a detector for ferromagnetic objects using a small passive coil to sense disturbances in the earth's magnetic field when an object moves near the coil. The circuit uses a multiplier in the form of an electronic switch on the output of the coil to impose a much higher frequency on the output of the coil. This separates the frequency of amplification from the frequency of the coil signal and makes it possible to sharply filter the signal, prevent false alarms from electrical noise, identify the direction in which the object is moving, and reduce the power consumed through the use of a sampling technique. The frequency conversion technique also allows for multiplexing of multiple coils by one signal processing circuit.

Abstract: A detector for detecting a characteristic and a speed of a vehicle includes a first magnetic field sensor. The first magnetic field sensor includes a magnetically variable resistor that changes resistance in response to being exposed to a magnetic field. A bias is applied to the magnetically variable resistor and a change in the resistance thereof in response to an applied magnetic field is detected by an amplifier. The amplifier generates a first analog signal indicative of changes in the resistance of the magnetically variable resistor. A differentiating circuit differentiates the first analog signal and produces a first output that changes binary state in response to detecting a predetermined change in the differentiated first analog signal. A counter accumulates values at a predetermined rate and a microprocessor stores values of the counter corresponding to each change in the binary state of the first output of the differentiating circuit.

Abstract: A method registers a vehicle in a road toll facility that is provided with radio transmitter and receiver units (7). The radio transmitter and receiver units are configured to communicate with at least one vehicle unit (12) arranged in the vehicle (4). The vehicle unit is configured with radio transmitter-receiver equipment so that on receipt of a command from the radio transmitter unit (7) of the road toll facility, the vehicle unit communicates adequate data for performance of a debiting operation regarding a toll. Upon the entry of the vehicle into the toll facility area, the transmitter and receiver units (7) of the toll facility determine whether the vehicle (4) is equipped with a vehicle unit capable of performing a correct debiting transaction.

Abstract: An underground vehicle sensing system extends below a vehicle travel surface to detect the presence of a vehicle. A conduit extends substantially horizontally underground from an access hole placed at the side of the vehicle travel surface. A plurality of sensors are spaced apart in the conduit to detect localized changes in the magnetic field. A plurality of sections house the probes and wiring to orient and position the probes. Sections detachably clip together to form a lightweight support structure and may be added one by one through the access hole. Lightweight extension members are utilized in some configurations between the support sections for positioning and supporting the probes.

Abstract: A device and method is provided for sensing an object or vehicle in proximity to a sensing zone, wherein the device is exposed to an environment temperature. The object sensing device comprises a sensor, such as an inductive loop having a characteristic, such as the inductance of the inductive loop, responsive to the proximity of the object is to the sensor; a signal generator, such as an oscillator, coupled to the sensor for producing a first periodical signal cycling at a first frequency dependent on the sensor characteristic and the environment temperature.