Abstract: A monitoring system for monitoring a first parameter includes an active sensor, a receiver and an indicator. The active sensor is positioned at a first location and is operable to sense the first parameter. The receiver is positioned at a second location remote from the first location and within proximity to the sensor. The receiver is operable to generate a signal indicative of the first parameter and includes a first inductor, a second inductor and an amplifier having a feedback path. The first inductor and the second inductor are positioned relative to one another to create an electromagnetically coupling between the inductors such that feedback from the coupling is one of either a substantially zero feedback and a negative feedback. The indicator is in communication with the receiver to provide the first parameter to the user. This parameter may include a tire pressure of a tire on a vehicle.

Abstract: A tire characteristic monitoring method allows automatic programming of tire position information in a remote tire pressure monitoring system (10). The method includes, from a remotely located exciter (16) using a primary coil (18) to transmit a relatively low frequency signal to a secondary coil (L1) of a tire monitor (12) associated with a tire of a vehicle. The method further includes the step of, at the tire monitor, in response to the relatively low frequency signal, transmitting a relatively high transmitting signal to convey data. The data are received at the exciter and subsequently loaded into a receiving unit (14) of the vehicle.

Abstract: An arrangement for provision of vehicle tire sensory information while a tire (12) is mounted on a wheel rim (10) of a vehicle. A sensor unit (16) includes a tire condition sensor (e.g., electronics 38), a signal transmitter (36), and a housing (20) that contains the sensor and the transmitter. The housing (20) has a mounting hole. A stud (18) is welded to the rim (10) and extends into the space bounded between the tire (12) and the rim (10). The stud extends through the mounting hole of the sensor housing (20). A retainer (e.g., 26) extends between the sensor housing (20) and the stud (18) such that the sensor housing is held fixed relative to the stud.

Abstract: A pressure detector system for vehicle tires, within each tire, a pressure detector/transducer for sending a signal reflecting a under-inflation condition in the tire, receiving antennas, placed adjacent to each tire, a visual display of the under-inflated tire, each tire valve having an enlarged pedestal, the pressure detector/transducer mounted within pedestal, a main air passage bore communicating with the air chamber and with the reference chamber, an outer valve core and a inner valve core having a sealing valve stem extending the length of the valve core, biased upwardly, the reference chamber having a deformable wall which moves outwardly when the air pressure within the air chamber falls below the air pressure in the reference chamber, the deformable wall having an electrical contact mounted on the exterior side, a rigid wall spaced apart from the deformable wall, having an electrical contact facing the electrical contact on the deformable wall, when the air pressure in the air chamber falls, the two

Abstract: A time-independent, event-based system for receiving and discriminating unique codes from multiple transmitters has an event-based detection cycle instead of a time-based detection cycle. The system detects received ID codes from multiple transmitters and compares the received ID codes with registers for ID codes in an array in memory. Counters corresponding to the stored ID codes increment each time there is a match between the received ID code and the stored ID code. After a predetermined total number of increments, the system evaluates the received signals to discriminate between ID codes received from desired transmitters and those from undesired transmitters before resetting the counter. Because the system is event based and not a function of time, it will operate over a wide range of time cycles.

Abstract: A monitoring device and patch combination used to monitor the conditions of a pneumatic tire having an innerliner includes a monitoring device and a patch. The monitoring device includes at least one sensing element that is adapted to sense a condition of the pneumatic tire. The monitoring device also includes a first electrical pad connected to the sensing element. The monitoring device and first electrical pad are preferably encapsulated in an encapsulation material. The patch is adapted to carry the monitoring device and mount the monitoring device on the innerliner of the tire. An antenna is embedded within the patch and a second electrical pad is connected to the antenna. The monitoring device is disposed on the patch in a manner such that the first and second electrical pads are aligned to provide electrical coupling between the pads. The antenna is in communication with the sensing element through the electrical coupling between the pads.

Abstract: The proposed device is fitted on vehicles equipped with pneumatic tires and is used for monitoring tire pressure. The device comprises: a pressure measurement sensor on each of the wheels (2) being monitored; a transmitter mounted next to each pressure measurement sensor which emits signals carrying the pressure data obtained from the pressure measurement sensor, and a receiver for those signals fitted on the vehicle chassis. An antenna (5a, 6a, 7a, 8a) is arranged next to each wheel (2) as the receiver. The antennae are connected to a common receiving and monitoring circuit (15, 17).

Abstract: A monitoring system for monitoring a first parameter includes a sensor, a receiver and an indicator. The sensor is positioned at a first location and is operable to sense the first parameter. The receiver is positioned at a second location remote from the first location and within proximity to the sensor. The receiver is operable to generate a signal indicative of the first parameter and includes a first inductor, a second inductor and an amplifier having a feedback path. The first inductor and the second inductor are positioned relative to one another to create an electromagnetically coupling between the inductors such that feedback from the coupling is one of either a substantially zero feedback and a negative feedback. The indicator is in communication with the receiver to provide the first parameter to the user. This parameter may include a tire pressure of a tire on a vehicle.

Abstract: In an apparatus for detecting the pressure condition in a pneumatic tire on a vehicle body, a pressure-responsive resonant switching device is mounted on the pneumatic tire and is switchable between a first impedance state, where pressure in the pneumatic tire is within a predetermined normal operating pressure range, and a second impedance state, where the pressure in the pneumatic tire is not within the predetermined normal operating pressure range. An excitation unit is mounted on the vehicle body adjacent to the pneumatic tire. A controller supplies an excitation signal to the excitation unit in order to enable the latter to co-act with the resonant switching device by virtue of mutual induction according to the impedance state of the resonant switching device for inducing current in the resonant switching device as the resonant switching device is moved so as to be proximate with the excitation unit due to rotation of the pneumatic tire relative to the vehicle body.

Abstract: A tire pressure indicator has a spring-operated sensor mounted in an air chamber of a housing that attaches to a tire pressure valve. Indicator has adjustment screws, accessible from the exterior of the housing, for setting the sensor to a low level of acceptable tire pressure and a high level of acceptable tire pressure. When the pressure level outside of the set limits is detected, a bicolor light emitting diode provides a warning to a driver.

Abstract: A method and apparatus for remotely measuring the pressure and temperature of the gas in a vehicle wheel The vehicle includes a frame member, a vehicle wheel mounted for rotation relative to the frame member about a rotation axis, and a modulator mounted on the vehicle wheel for movement therewith The modulator generates a carrier signal including a first component encoding a plurality of consecutive data signals corresponding to a physical characteristic of the vehicle wheel, and the carrier signal including a second component identifying a portion of the respective one of the data signals

Abstract: A device and process for monitoring the condition of the tires of a vehicle and of their environment is disclosed. The device uses a central unit and a wheel module with at least one measuring sensor for each wheel. The module is electrically connected to a rotating antenna firmly attached to the hub of the wheel, as well as a stationary antenna firmly attached to the hub housing of the wheel and connected to the rotating antenna. The stationary antenna is electrically connected to the central unit for transmitting to the driver the results of the measurements and/or an alarm if an abnormal condition of the tires is detected and the antennae being laid out in the environment of the braking mechanisms of the wheel and characterized in that it includes a sensor for estimating the temperature of the braking mechanism. The sensor includes one of the antennae being sensitive to variations in temperature.

Abstract: A vehicle including a frame member and a vehicle wheel mounted for rotation relative to the frame member about a rotation axis. The vehicle also includes a transmitting circuit mounted on a one of the frame member and the vehicle wheel. The transmitting circuit includes an antenna coil having a diameter. A ferrite core is mounted adjacent the transmitting circuit on the one of the frame member and the vehicle wheel. A non-planar, curved antenna coil is mounted on the other of the frame member and the vehicle wheel. The non-planar, curved antenna coil has a radius of curvature that is approximately equivalent to the rotational pathway of the transmitting circuit.

Abstract: The invention is directed to a method and apparatus for detecting a tire inflation pressure of a vehicle tire. The apparatus includes a device for producing an oscillating electric signal having a vibration frequency component of the vehicle tire. A wavelet transformer transforms the oscillating electric signal by a wavelet function into a wavelet coefficient. The wavelet function is provided on the basis of a mother wavelet function localized in time, scaled in response to a scale parameter, and shifted in response to a shift parameter indicative of a time localization. Then, an extracting device extracts a resonance frequency from the vibration frequency component of the vehicle tire on the basis of the wavelet coefficient, and an estimating device estimates the tire inflation pressure on the basis of the resonance frequency.

Abstract: A system is provided for monitoring tire pressure which includes a sensor mounted within a tire that triggers a train of pulses when tire pressure reaches a level outside predetermined parameters. The system also includes a receiver mounted in operative proximity to the sensor at a location exterior to the tire. The receiver is electromagnetically coupled to the sensor and the sensor is activated in response to tire pressure reaching a level outside predetermined parameters. Also provided is an indicator which is coupled to the receiver, which signals when the tire pressure reaches a level outside predetermined parameters. The sensor is mounted within the tire that senses tire air pressure. The receiver is mounted within operative proximity to the sensor and at a location external to the tire and is electromagnetically coupled to the sensor to generate signals dispersed by the sensor that are indicative of tire air pressure sensed by the sensor.

Abstract: Pickup coils which generate vehicle wheel speed signals which include vibration frequency components of tires during vehicle cruising are provided. An electronic control unit extracts resonance frequencies of tires from the vehicle wheel speed signals and estimates tire pneumatic pressure based on the extracted resonance frequencies. When an estimated vehicle wheel pneumatic pressure falls below a predetermined critical pneumatic pressure, pneumatic pressure decline warnings are generated and displayed by a display unit. An update switch is provided and when this update switch is turned on when replacing tires, the electronic control unit adjusts and sets the value of the critical pneumatic pressure described above based on the resonance frequency extracted during this time.

Abstract: Tire vibration frequency components of left-hand and right-hand tires are derived from wheel speed signals while a vehicle is traveling. A noise frequency component is detected based on a correlation between the vibration frequency components of the left-hand and right-hand tires, and the noise frequency component is reduced relative to the vibration frequency component. Thereafter, resonance frequencies of each tire are detected using the vibration frequency component from which the noise frequency component is reduced, and tire air pressures are detected on the basis of the resonance frequencies.

Abstract: A valve cap is screwed onto a pneumatic tire and generates an indication whether a prefilled tire pressure is still existent or not. For this purpose a valve cap (1) comprises a deflectable diaphragm (30) in an inner housing separating a pressure chamber from a reference pressure chamber. The reference pressure chamber registers the prefilled tire pressure. The diaphragm (30) is deflected toward the closed housing end when the actual existent tire pressure drops in comparison with the registered tire pressure. Onto the diaphragm (30) a permanent magnet (40) is placed, which can be in a first position (normal position of the diaphragm) or in a second position adjacent to the housing end. The check of the magnet position and the generation of an indication signal indicative of the actual tire pressure status will be executed by a hand device, which must be brought into a defined position with respect to the valve cap.

Abstract: A magnetic-flux change-generating device 2 causes amplitude modulation of alternating magnetic flux in accordance with displacement of a movable body, and an amplitude-compensating device (low-pass filter) 4 causes attenuation of amplitude of electromagnetic-induction voltage of a pickup coil 3 substantially proportionally to frequency. When frequency of the alternating magnetic flux (also termed "carrier frequency") fluctuates, the amplitude of the electromagnetic-induction voltage fluctuates in proportion to the frequency, but because the amplitude of the electromagnetic-induction voltage is caused to be attenuated at an attenuation rate which is substantially proportional to the frequency, displacement can be detected accurately by this amplitude change, irrespective of change in the frequency of the alternating magnetic flux (i.e., the carrier frequency of the electromagnetic-induction voltage).

Abstract: It is an object of the present invention to detect a tire air pressure indirectly with high detection precision.A tire air pressure detecting device includes a speed sensor for outputting a signal corresponding to a rotational speed of a tire, and an electronic control unit which inputs the signal from the speed sensor and performs predetermined arithmetic operations on that signal. The electronic control unit calculates a wheel speed based on the output signal of the speed sensor, performs a frequency analysis for the calculated vehicle speed, and derives a resonance frequency corresponding to the unsprung mass in the vertical and longitudinal directions. The tire air pressure is then detected based on this resonance frequency.

Abstract: Embedded smart structures include active electronics which control and collect data from sensors and actuators and transmit data to the exterior of a body by electromagnetic antenna radiation to a conformal power and data interrogation interface. Multiple embedded smart structures are powered and interrogated by a network of conformal powering and interrogation units. Multiple embedded sensors each having an antenna with a defined narrow band resonant frequency are powered and interrogated by a single external powering and data interrogation antenna.

Abstract: A self-regulating tire pressure system and method employs a bistable valve (10) that allows air from a high pressure reservoir (6) to replenish the pressure within a tire (4) when it has fallen below an actuating pressure, and discontinues its operation only after the tire pressure has increased to a closing pressure that is greater than the actuating pressure. The system is capable of sensing the valve's (10) frequency of operation as an indication of a slow tire leak when the frequency exceeds a predetermined threshold, of sensing the number of valve (10) operations and the duration of each operation as an indication of a flat tire condition when the number of operations for a predetermined duration exceeds a second threshold, and of sensing the duration of the valve's (10) operation as an indication of a low reservoir (6) pressure condition when that duration exceeds a third threshold.

Abstract: An arrangement for monitoring operating parameters of vehicle pneumatic tires mounted on wheel rims is provided with sensors (58, 60) for selected operating parameters and with transmitting means comprising rim-side mounted rotor members (28) and bodywork-side mounted stator members (32) coupled thereto for transmitting the operating parameters detected by the sensors (58, 60) to an evaluating arrangement in the vehicle connected to the stator members (32). In an opening (20) of the wheel rim (10) in the region of the rim well (22) a measuring module (24) comprising two components (36, 38) detachably connected together is disposed. One of the components (36, 38) is mounted on the side facing the tire (14) and the other is mounted on the side of the rim well (22) remote from the tire (14). The sensors (58, 60) are mounted on one of the two components (36).

Abstract: A method and apparatus for measuring a physical quantity, property or condition and for transmitting a code representing the measured physical quantity, property or condition. The method includes the steps of developing a first signal in response to a physical quantity, property or condition, sampling the first signal to produce an instantaneous first signal value, assigning a first code to the instantaneous first signal value, and transmitting the first code for reception by a receiver. The method and apparatus are explained in connection with a vehicle tire monitoring apparatus wherein plurality of tire units measure tire pressures and temperatures and transmit values representing pressure and temperature to a central receiver located in a cab portion of the vehicle.

Abstract: A self-regulating tire pressure system and method employs a bistable valve (10) that allows air from a high pressure reservoir (6) to replenish the pressure within a tire (4) when it has fallen below an actuating pressure, and discontinues its operation only after the tire pressure has increased to a closing pressure that is greater than the actuating pressure. The system is capable of sensing the valve's (10) frequency of operation as an indication of a slow tire leak when the frequency exceeds a predetermined threshold, of sensing the number of valve (10) operations and the duration of each operation as an indication of a flat tire condition when the number of operations for a predetermined duration exceeds a second threshold, and of sensing the duration of the valve's (10) operation as an indication of a low reservoir (6) pressure condition when that duration exceeds a third threshold.

Abstract: The pneumatic pressure in a tire on a wheel of a vehicle is introduced into a pressure chamber positioned at a central axis about which the tire is rotatable through a communication passage defined in the wheel. When the pneumatic pressure in the pressure chamber varies, a diaphragm or bellows attached over the pressure chamber is elastically displaced, axially moving a slide bar extending axially through a wheel shaft on which the wheel is supported. The movement of the slide bar displaces a ferromagnetic member in a coil, whose inductance then varies. The change in the coil inductance is detected by an electronic control unit, which transmits a signal to a display unit.

Abstract: A tire pressure detecting portion includes a housing, provided within the tire, within which a piezoelectric element is provided so as to be deformed by the tire pressure. The capacitance of said piezoelectric element is changed in accordance with its deformation. The piezoelectric element is electrically connected with a first coil diposed within said tire. The first coil is electromagnetically coupled with an excitation coil and a receiving coil, both of which are provided in the vehicle. The excitation coil provides an excitation voltage whole frequency is changed within a predetermined range including a resonant frequency. When the received voltage has the resonant frequency, a correspondinq tire pressure is determined based on a data map showing the relationship between said resonant frequency and the tire pressure.

Abstract: A device for monitoring the state of the tire of a vehicle wheel and for measuring the rotation characteristics of the wheel is described herein. The device includes a rotating encoder element constituted by a multipolar magnetic ring, whereby magnetic segments of different polarity are distributed circumferentially in a regular and alternating manner. The device further includes a transmitter coil mounted coaxially with the multipolar ring, a fixed pick-up element constituted by an induction coil enclosed in a U-shaped section of an annular flux focusing element arranged coaxially with the multipolar magnetic ring. The device is energized by an alternative electric current flowing through the transmitting coil which generates a magnetic field superimposed on the magnetic field created by the multipolar magnetic ring, wherein the pick-up element delivers a signal relating to the rotation characteristics of the wheel and the state of the tire.

Abstract: A pneumatic tire has an integrated circuit transponder which, upon interrogation by an external RF signal, transmits tire identification and tire pressure data in digitally-coded form. The transponder has an antenna adjacent and thereby coupled by electric or magnetic fields to an annular tensile member comprising a bead of the tire. The antenna has lead wires that preferably are positioned between the innerliner of the tire and its continuous carcass ply. The transponder thus is on the axially inner side of the reinforced carcass ply. A pressure transducer is within the transponder and is responsive, preferably through the innerliner material, to pressure within the tire. If the antenna is a coil, the coil is substantially planar in shape and parallel with the reinforced carcass ply. The transponder and pressure transducer also can be attached to the axially inner side of the innerliner.

Abstract: An antenna to be used with transponder type devices. The antenna includes an inductance and a capacitor forming a resonant circuit. To avoid any heating and to have a sufficiently broad passband or operating range, there is in parallel with the inductance, a branch comprising two Zener diodes connected in opposite directions. Any nonlinear damping arrangement having an equivalent effect may be used in the branch.

Abstract: A device for measuring physical values, each as pressure changes, includes a sensor transponder section and an interrogator receiver section for transmitting interrogation signals including a power supply from the interrogator receiver section to the sensor transponder section and for transmitting measured signal values in the opposite direction. The sections can be coupled to each other by inductive coils so that electrical connections are avoided. Thus, the pressure in a rotating automobile tire can be measured, for example. The sensor transponder section includes a computer circuit the input of which receives a reference frequency signal and a measured frequency signal. A reference oscillating signal has a frequency determining element that is not influenced by the pressure to be measured, but only by extraneous, e.g. environmental influences. A measuring oscillating circuit has a frequency determining element that is responsive to the changes in the physical value to be measured.

Abstract: A circuit arrangement is suggested for monitoring the air volume in vehicle tires which effects the most accurate possible correction of the temperature measured by a sensor fastened at the wheel to the actual air temperature in the tire. For this purpose, the temperature and pressure measurement value of the tire measured by the rotating sensor (13) of the wheel to be monitored is fed to a correction circuit (18) which is also receives a plurality of correction parameters (p, F, K, v). A corrected value for the temperature (t.sub.k) or for the air pressure in the tire is transmitted at the output of the correction circuit (18) as a function of the correction parameters (FIG. 1).

Abstract: The tire pressure sensor (13) for monitoring vehicle tires is fastened radically relative to the wheel axis at the circumference of a wheel rim and includes a reference pressure chamber (20) with a contact pin (22) which cooperates with an electrically conductive diaphragm (21) closing the reference pressure chamber (20) toward the tire. An added mass (30) is fastened freely at the diaphragm center for raising the switching threshold of the tire pressure sensor (13) as a function of speed and is dimensioned in such a way that the switching threshold is raised by a desired pressure differential (.DELTA.p) relative to the switching threshold p.sub.o at standstill at a predetermined radius r of the diaphragm (21), a predetermined rotational radius R of the diaphragm (21) and a predetermined rotational speed v of the diaphragm (21). The required added mass (m) results from the equation m=f(.DELTA.p, r.sup.2, R, v.sup.2), advantageously m=(.pi./4)r.sup.2 {[R/v.sup.2 ].DELTA.p - p.

Abstract: In a device for the transmission and evaluation of measurement signals for the tire pressure of tubless tires mounted rims in single and twin wheels of motor vehicles which comprises a pressure sensor (6) arranged in the rim wall, which pressure sensor (6) is electrically connected with a signal transmitter coil (8) arranged at the rim (3), as well as a signal pick-up coil (20) of a high-frequency resonant circuit signal evaluating arrangement connected with the motor vehicle in the area of the axle so as to be stationary, it is provided for the purpose of enabling signal detection also when stationary and for problem-free application to twin tires, that a first repeater coil (15), which is electrically connected with a second repeater coil (17), is arranged in the area of the signal transmitter coil (8) at the hub (12) carrying the rim (3), which hub (12) is connected with the latter so as to be fixed with respect to rotation relative to it, wherein the second repeater coil (17) is constructed as a toroidal

Abstract: A device for exciting and monitoring wheel modules for monitoring tires crises control lines (5, 6) which excite simultaneously all the wheel modules except one, which is monitored. For this purpose, it comprises one exciting and monitoring assembly (2) per wheel. Each assembly (2) comprises an insulation transformer (20) of which the secondary (21) has a central point (21N) connected to earth. This arrangement ensures good electromagnetic compatibility and good insensitivity to radio frequencies.

Abstract: A tire abnormality detecting device has a first unit to be provided on a vehicle body side and a second unit to be provided on a tire side. The first unit includes an electrical signal generating source for generating a specific electrical signal, a first coil device for generating an induction voltage in receipt of the electrical signal, and a device for detecting a change in the induction voltage of the first coil device. The second unit includes a second coil device adapted to be magnetically connected to the first coil device, a third coil device having a magnetic core formed of a temperature sensing magnetic material to form a resonance circuit in cooperation with the second coil device, and a switch mechanism for changing a time constant of the resonance circuit in response to a change in air pressure in a tire. With this construction, the abnormal reduction in air pressure in the tire and/or the abnormal increase in temperature of the tire can be detected.

Abstract: In a tire valve suitable for detecting the pressure and temperature in a tire, the strain of the tire wheel and the like, a conductive core body of a valve core is electrically insulated from a conductive shaft, and, to a pedestal having a 1st electrode electrically shaft and a 2nd electrode electrically connected to a conductive valve stem via a core spring, a sensor having two sensor electrodes connected with the 1st and 2nd electrodes respectively is fixed.

Abstract: An apparatus for monitoring the air pressure in a pneumatic tire carried by the rim of a vehicle wheel, comprising a sensing element which is arranged at the rim ring and which can be deformed and acted upon by the tire pressure, with a permanent magnet as the measurement value generator, in the region of rotary movement of which is disposed a measurement value sensor which is fixed to the vehicle in a stationary position and which is connected to an evaluation circuit. The apparatus is reliable in operation and uncomplicated in structure.

Abstract: An interface circuit serves to rectify excitation energy inductively coupled to a transistor acting in a diode configuration to charge a reservoir capacitor which may then serve as a power source. Switch means under the control of an external functional circuit block is arranged to bias the transistor into a reverse operating mode to itself act as a switch to discharge energy from the reservoir into the coupling. In this way pulses may be back coupled to be detected at the excitation source. The timing of the back coupled pulses may be information bearing.

Abstract: A method and apparatus are provided wherein there is associated with each value of a measurement of a parameter such as pressure, for transmission through an electromagnetic coupling device, a time duration or period which is a function of the measured value. A first, start signal of relatively short duration is transmitted and thereafter, at the end of a period which is a function of the parameter, a second, ending signal of relatively short duration is transmitted. A receiving device which is responsive to said signals, measures the elapsed time between them, i.e., measures the length of the intervening period, and converts this measurement into a measure of the parameter.

Abstract: A device for inspecting the pressure, temperature, etc. in a tire includes a pressure sensor attached to a valve mounted on the tire rim and having an output that varies depending upon the tire internal pressure, and a resonator including a resonant coil and capacitor which resonates in the presence of an external radiation electromagnetic wave. An oscillation coil of an oscillator which generates the external radiation electromagnetic wave projects from the main body of the inspection device. The main body encloses a signal processor which detects and processes any change in oscillation state which has taken place at the oscillator, as caused by the resonance state of the resonator, and a display to display the result of the signal processing by the signal processor.

Abstract: A circuit arrangement for transmitting variable measurement values, such as pressure and temperature, at vehicle wheels is provided which transmits the measurement values in the form of H-F signals to a stationary evaluating circuit (12) with great accuracy, high reliability and in short time intervals. A repeater coil (b 13), which is connected with the latter, arranged in the vicinity of the wheel so as to be stationary and connected to voltage by a square-wave generator (15), cooperates with a revolving repeated coil (19) which is fastened at the vehicle wheel and connected with a sensor circuit arrangement (20) supplied by it.

Abstract: A tire pressure sensing system for on-board use in an automotive vehicle comprises a transmitter mounted to rotate with each tire and a receiver that is disposed in sensing relationship to each transmitter. Each receiver is a Hall Effect sensor. Each transmitter comprises three magnetic poles that are effective to cause the Hall Effect sensor to develop a bi-directional pulse waveform during passage of the transmitter past the receiver. Electronic circuitry processes the signal waveform that is created by the Hall Effect sensor in response to passage of the magnetic poles. The circuitry develops one rectangular pulse waveform from one magnetic polarity and another rectangular pulse waveform from the other magnetic polarity.