DETECTION ARRANGEMENTS

摘要

A detection system in which a single sensor (14) is employed to detect two, or more, levels, or ranges, of a parameter. The output signal from the sensor (14) is fed to a detection circuit (12) for amplification and thence to a control circuit (24). The control circuit (24) is switchable, either manually, or preferably programmably, for example by a timer, between two or more modes of operation for processing the output signal from the sensor (14) in a different manner, for example using different algorithms, according to the condition that is to be detected. The switching of the control circuit (24) between its modes results in a signal being sent to the detection circuit (12) to change its sensitivity to the signal received from the sensor (14), thereby to maintain accuracy of measurement of the parameter in both or all modes of operation.