Method and apparatus for measurements of a characteristic of an object using a sensed signal and an auxiliary variable signal applied to the object

摘要

An apparatus for measuring a measurable characteristic of an object includes a sensor element which emits an analog sensor output signal, the sensor output signal corresponding to the measurable characteristic of the object, an analog/digital converter for converting analog signals from the sensor element into digital output signals, a processor receiving the digital output signals and supplying a control signal to the controllable auxiliary variable generator. The controllable auxiliary variable generator is controlled by the control signal emitted by the processor, and the auxiliary variable signal is interrupted for a selected time span after each measuring interval. The processor filters out components of the measurable signal emitted by the sensor element which are caused by the auxiliary variable signal, by analyzing the signal produced by the controllable auxiliary variable signal generator together with the output signals from the analog/digital converter to form a resultant function, so that the processor can determine an accurate value of the measurable characteristic of the object.