Abstract: An electronic timing apparatus for determining precisely when vehicles pass over a particular line on a road, particularly a race track (20), has a series of separate loop antennas (26), arranged in closely adjacent relationship one to another across the width of the track. Each vehicle (81,82) is fitted with a transmitter (28) for transmitting a unique identifying signal which is received by a loop antenna as the vehicle passes over the line. The width (x) of the antenna loops relative to the width of the vehicles is such that only one transmitter (28) can pass over a particular loop at the one time whereby when two or more vehicles cross the line simultaneously, signals from the respective transmitters are received in different antennas. A respective receiver module (27) is connected to each antenna loop and processes the identifying signal which is then fed to a micro-controlled (43) which calculates the time at which the particular vehicle crossed the line.

Abstract: A transceiver unit for an electronic surveillance system is internally coded with an address-number for identification within the system and is adapted to receive input from sensors detecting alarm conditions. The unit is switchable from an idle condition wherein it transmits digital data relevant to its address-number and status but does not recognize input from a sensor, to a primed condition wherein it transmits digital data relevant to its address-number and status information indicating an alarm condition. The unit is able to receive digital data from other similar units sequentially and display information relevant to the identity and status thereof. In a security system a plurality of such units communicate with each other and in turn transmit the digital data to all the other units of the system simultaneously, either by hard wiring thereto, radio link or other transmission medium. An alarm condition detected by one unit is recognized at all other units of the system.

Abstract: A position indicator for monitoring movement of one part of an assembly relative to another--e.g., for monitoring the relative positions of the movable and fixed jaws of a gyratory crusher. The position indicator has a body which is fixed to a probe suitable support and a variable capacitor which responds to movement of the member to be monitored to adopt a capacitance value which is characteristic of each position of that member relative to the support. The capacitor is connected into an electrical circuit operative to generate a signal which varies according to the capacitance value and therefore provides an indication of the position of the member being monitored. The probe body includes at least two telescopic tubes arranged so that the body extends and contracts in accordance with movement of the member being monitored and conductive parts of the variable capacitor are connected to the tubes, so that their relative positions change with extension and contraction of the probe body.