Abstract: A SAW sensor arrangement includes a transducer including a support for supporting a SAW device. The support includes a sensor location part located between two oppositely extending attachment parts. The SAW device is mountable to the sensor location part. The sensor arrangement 10 includes at least two spaced friction raisers. The sensor arrangement includes a clamp arrangement which applies a clamping force to clamp the sensor arrangement to an item. The sensor arrangement is arranged so that in use each of the friction raisers is located between a different one of the attachment parts and the item.

Abstract: A SAW sensor arrangement includes a transducer including a support for supporting a SAW device. The support includes a sensor location part located between two oppositely extending attachment parts. The SAW device is mountable to the sensor location part. The sensor arrangement 10 includes at least two spaced friction raisers. The sensor arrangement includes a clamp arrangement which applies a clamping force to clamp the sensor arrangement to an item. The sensor arrangement is arranged so that in use each of the friction raisers is located between a different one of the attachment parts and the item.

Abstract: A method of wirelessly interrogating a sensing device comprising a plurality of passive sensors, to determine a measurement parameter, comprises the steps of repeatedly interrogating the sensing device using a predetermined transmission signal and detecting the response; estimating the measurement parameter for each sensor by means of an analysis of the data accumulated as a result of the interrogation step, and determining the average of the parameters derived from the estimating step for each sensor, using a weighted average, in which the weightings depend on the amplitude of the sensor response. The measurement parameter may be a resonant frequency where the passive sensors are resonant devices, and the sensors may be SAW devices.

Abstract: A contactless SAW based torque and temperature sensor comprising a first (2) and second (3) SAW resonator provided on a substrate made of Y+34° cut of quartz. The first SAW resonator (2) has its principle axis inclined at +45° to the X-axis of the substrate, which, in use is either aligned with the longitudinal axis of the device who torque is to be measured or is perpendicular thereto, and the second SAW (3) has its principle axis inclined at ?45° to the X-axis of the substrate. A third SAW (4) has its principle axis inclined at an angle of 30 degrees to the X-axis of the substrate. Each said SAW resonator (2,3,4) is formed by laying a film of aluminum on the substrate having a thickness (h) and the SAW resonators have an average operating wavelength ? where the ratio h/? is in the range 0.021 to 0.032.

Abstract: A method of calibrating an individual sensor of a particular sensor type whose output varies non-linearly with at least one measured quantity and at least one operating condition. The first step includes producing a set of calibration curves for each sample sensor of the particular sensor type. The resulting sets of calibration curves are then averaged and the results used to produce a generic calibration surface for the particular sensor type showing its variation. Individual calibration measurements are then taken for a number of different values of the measured quantity at a small number of discrete values. The individual calibration readings are then used to map the generic calibration surface to the individual calibration measurements of the individual sensor.

Abstract: A method of wirelessly interrogating a sensing device comprising a plurality of passive sensors, to determine a measurement parameter, comprises the steps of repeatedly interrogating the sensing device using a predetermined transmission signal and detecting the response; estimating the measurement parameter for each sensor by means of an analysis of the data accumulated as a result of the interrogation step, and determining the average of the parameters derived from the estimating step for each sensor, using a weighted average, in which the weightings depend on the amplitude of the sensor response. The measurement parameter may be a resonant frequency where the passive sensors are resonant devices, and the sensors may be SAW devices.

Abstract: A contactless SAW based torque and temperature sensor includes three SAW resonators 2, 3, 4 mounted on a common substrate 1 made of Y+34° cut of quartz. The first SAW 2 has its principle axis inclined at +45° to the X-axis of the substrate, which, in use, is either aligned with the longitudinal axis of a device whose torque is to be measured or is perpendicular thereto, and the second SAW 3 has its principle axis inclined at 135 degrees to the X-axis of the substrate. The third SAW 4 is positioned with its principle axis inclined at an angle, preferably in the range of 0 to 30 degrees, to the principle axis of both the first 2 and second 3 resonators so that none of the SAWs are parallel, the third SAW 4 enabling temperature measurements to be taken.

Abstract: A rotary coupler comprises a stator 1 having a first face 3a and a rotor 2 having a second face 4a, the first and second faces 3a, 4a being spaced apart from and facing each other. A first electrically conducting track 5 is provided on the first face 3a of the stator 1 which forms a transmission line and has spaced apart ends A, B and a second electrically conducting track 6 is provided on the second surface 4a of the rotor 2 also forming a transmission line and having spaced apart ends C, D. One end A of the first track 5, in use, is connected to signal generating means and the other end B of the first track is connected to earth through a resistor substantially equal to the characteristic impedance of the transmission line. The first track 5 extends along a generally circular arc substantially around the first face 3a of the stator 1, the first track 5 having a length substantially equal to an integer number of wavelengths of the signal produced, in use, by the signal generating means.

Abstract: A contactless SAW based torque and temperature sensor comprising a first (2) and second (3) SAW resonator provided on a substrate made of Y+34° cut of quartz. The first SAW resonator (2) has its principle axis inclined at +45° to the X-axis of the substrate, which, in use is either aligned with the longitudinal axis of the device who torque is to be measured or is perpendicular thereto, and the second SAW (3) has its principle axis inclined at ?45° to the X-axis of the substrate. A third SAW (4) has its principle axis inclined at an angle of 30 degrees to the X-axis of the substrate. Each said SAW resonator (2,3,4) is formed by laying a film of aluminum on the substrate having a thickness (h) and the SAW resonators have an average operating wavelength ? where the ratio h/? is in the range 0.021 to 0.032.

Abstract: The present invention relates to a method and apparatus for assessing the condition of a wheel particularly, but not exclusively, to a method and apparatus for assessing the condition of a tire rotating on a vehicle wheel. Apparatus is provided comprising a plurality of antennas (101, 102, 103, 104, 105, 106, 107, 108) for transmitting an interrogation signal to a sensor (110, 112), the sensor being mounted to a wheel to be assessed and being adapted to detect the condition of the wheel; wherein the antennas are arranged in a line along a path to be followed by a wheel to be assessed.

Abstract: A self-contained radio apparatus for the transmission of data includes a resiliently deformable patch, a resiliently deformable antenna carried by the patch, a post secured to the patch and upstanding from an upper surface of the patch, the post providing at an end remote from the patch a mounting for a radio device, and, electrical conductors extending from the antenna to the end of the post remote from the patch for operably connecting the antenna to a radio device mounted on the post. The radio apparatus is useful for attaching to objects that undergo bending stresses, such as tires.

Abstract: A contactless SAW based torque and temperature sensor includes three SAW resonators 2, 3, 4 mounted on a common substrate 1 made of Y+34° cut of quartz. The first SAW 2 has its principle axis inclined at +45° to the X-axis of the substrate, which, in use, is either aligned with the longitudinal axis of a device whose torque is to be measured or is perpendicular thereto, and the second SAW 3 has its principle axis inclined at ?45° to the X-axis of the substrate. The third SAW 4 is positioned with its principle axis inclined at an angle, preferably in the range of 0 to 30 degrees, to the principle axis of both the first 2 and second 3 resonators so that none of the SAWs are parallel, the third SAW 4 enabling temperature measurements to be taken.

Abstract: A split ring coupler comprising a stator ring having at least one split in it such that the stator has at least a first and a second end and a rotor ring having at least one split in it such that the rotor ring has at least a first and a second end, said rotor ring being oriented substantially coaxially with and axially spaced apart from said stator ring. At least one SAW resonator is electrically directly coupled between said first and second ends of the rotor ring in series therewith, neither of said ends of said stator ring being connected to ground.

Abstract: A method of calibrating an individual sensor of a particular sensor type whose output varies non-linearly with at least one measured quantity and at least one operating condition, comprises producing a set of calibration curves for each of a number of sample sensors of the particular sensor type, each curve showing the variation of the sample sensor output with the at least one measured quantity at a different value of the operating condition for the particular sensor type of said individual sensor, said set of curves covering the required operating range for the particular sensor type. The resulting sets of calibration curves of the plurality of sensors derived are then averages and the results used to produce a generic calibration surface for the particular sensor type showing the variation of the sensor reading with the at least one measured quantity across the required operating range.

Abstract: A SAW based sensor having a base and a lid engageable with the base to form an internal cavity therewith. A substrate is supported in the cavity on either tile base or the lid 13 and a dimple 16 is formed on the other which extends towards the substrate so as to engage against the substrate and apply a preload thereto. The base and lid include complementary threads by means of which they are attachable to each other. The preload applied to the substrate by the dimple 16 is adjustable by varying the rotational position of the lid relative to the base.

Abstract: A rotary coupler comprises a stator 1 having a first face 3a and a rotor 2 having a second face 4a, the first and second faces 3a, 4a being spaced apart from and facing each other. A first electrically conducting track 5 is provided on the first face 3a of the stator 1 which forms a transmission line and has spaced apart ends A, B and a second electrically conducting track 6 is provided on the second surface 4a of the rotor 2 also forming a transmission line and having spaced apart ends C, D. One end A of the first track 5, in use, is connected to signal generating means and the other end B of said first track IS connected to earth through a resistor substantially equal to the characteristic impedance of the transmission line. The first track 5 extends along a generally circular arc substantially around the first face 3a of the stator 1, said first track 5 having a length substantially equal to an integer number of wavelengths of the signal produced, in use, by the signal generating means.

Abstract: A method of calibrating an individual sensor whose output varies with at least one operating condition. A generic calibration curve is produced for the variation of the sensor reading with the at least one operating condition for the particular sensor type of the individual sensor. Calibration readings are then taken for the individual sensor at just a small number of discrete values for the at least one operating condition which fall within the full range of operating values for the at least one operating condition for which the sensor is to be calibrated. Using the calibration readings, the generic calibration curve is then scaled in order to fit the generic curve to the individual sensor.

Abstract: A surface acoustic wave (SAW) sensor includes a transducer (240 provided on a substrate (23), wherein the transducer (24) is oriented on the substrate (23) so that the direction of acoustic wave propagation is such that the variation of sensor output with temperature, associated with the variation of the substrate third-elastic constants with temperature, substantially equal but opposite to the sum total of the variation of sensor output with temperature associated with the substrate linear temperature coefficient of expansion and with the variations with temperature of the substrate non-zero third order elastic constants, the substrate first-order elastic constants and the substrate density. The effect of temperature variation on sensor output is thereby minimized. This is achieved with a 35-degree arrangement or with reflective gratings inclined at an angle of 3.1 degrees to normal. Additionally, a robust package with a dish is given. Particular applications include the measurement of torque.

Abstract: A system for interrogating a tire sensor. The disclosure provides a wheel (2) including a sensor (14) and an electrical conductor (18, 20) extending about a rotational axis (4) of the wheel (2), the sensor (14) being electrically coupled to said electrical conductor (18, 20). Communication between the sensor and a remote interrogating apparatus is thereby improved.

Abstract: A pressure monitor has a base and a lid secured to the base to define a substantially fluid tight chamber. At least part of the lid is flexible and forms a diaphragm which deflects responsive to changes in fluid pressure surrounding the monitor. A projection provided on the diaphragm transmits movement thereof to a distortable substrate located within the chamber. A first SAW device is mounted on the distortable substrate, and at least a second and third SAW device are mounted within the chamber. The second SAW device carried on a reference substrate section has its direction of propagation inclined at an angle to the direction of propagation of at least one of the first and third SAW devices. This way movement of the diaphragm induced by a change in pressure in the zone surrounding the monitor results in distortion of the distortable substrate, which is measurable by the SAW device mounted thereon, without distorting said reference substrate section.