Abstract: A vehicle wheel speed sensor has a rotor 11 provided with a series of circumferentially spaced rotor elements 12 mounted on a wheel axle 10. A sensor 13 mounted on a relatively non-rotatable support is influenced by passage of the rotor elements to output a sine wave signal. The sine wave signal is fed for processing to an interface unit 15 on the vehicle and pulses are generated at at least two predetermined phases of each cycle of the sine wave. A method of producing marker pulses by detecting the zero cross-over points and the peaks and troughs of a sine wave signal, and generating a marker pulse at each zero cross-over point and at each peak and trough of the sine wave signal is also described.

Abstract: Inflation pressure of an inflated article, e.g. a wheel tire 12, is measured by pressure sensing apparatus 10 located on the inflated article. Portable apparatus 20 is brought into proximity with the sensing apparatus 10 and a power signal is transmitted for the portable apparatus to energise the sensing apparatus. The portable apparatus acquires pressure data signals output by the sensing apparatus, processes these data signals and displays an inflation pressure value. The power signal and pressure data signals are transmitted by engaging a probe 24 provided as part of the portable apparatus with a cylindrical body member 13 of the sensing apparatus. A particular advantage of the portable apparatus is in acquiring and displaying inflation pressure values of aircraft undercarriage wheel tires because the aircraft power does not have to be switched on and the cockpit entered to obtain inflation pressure readings.