Abstract: Measuring ethanol vapour concentration comprising; introducing an ethanol vapour sample into a fuel cell that is adapted to generate an output which is proportional to the ethanol vapour concentration of the ethanol sample; a voltage measurement circuit; a current measurement circuit; and means to switch the fuel cell output either to the voltage measurement circuit or to the current measurement circuit in dependence on one or more predetermined signal measurement parameters. The signal measurement parameter may be the temperature of the fuel cell.

Abstract: This invention relates to a vehicle security device. It relates, more particularly, to a security device or system which operatively serves as an alarm and/or immobilizer. The invention provides a vehicle security system including first and second parts, each including an electronic sub-circuit and a housing, and a communications link. In the operative configuration of the system on a vehicle, the first part is permanently mounted on the vehicle and the second part temporarily. The sub-circuits are interconnected via the link to define an integral control circuit, thus rendering the system operative. Should the vehicle be sold and the purchaser not require the system, the second part and the link may be removed and re-used by the seller. The value of only the first part is sacrificed by the seller. The system is aimed primarily at vehicle dealers.

Abstract: This invention relates to a vehicle security system. The invention provides a vehicle security system which can be armed and disarmed via a remote control device, e.g. an RF device. The system includes also sensing means which can sense a predetermined event indicative of the presence of a person at the vehicle, such as knocking on the vehicle. For disarming the system, it requires a disarm signal from a compatible remote control device as well as the predetermined event to occur within a predetermined short time period. Where a number of such systems are installed on a number of vehicles on the same lot, e.g. a dealership showroom, and are armed, one of them may be selectively disarmed via a remote control device common to all of the systems. Only the system which senses the predetermined event in addition to a disarm signal will be disarmed.