Method for determining slope in very noisy measurement signals

摘要

The detection of the change in a measurement signal for process control purposes is quite frequently impeded by superimposed interference, particularly noise peaks. Interposition of filters or increasing the sampling interval for gradient determination greatly delays the signal. In addition, noise peaks cause errors at the starting point and end point in the determination of a difference. The present invention has the aim of avoiding these disadvantages by only taking into consideration only a fraction of each change so that as a result, an exponential settling process is produced as response to a step change. A circuit arrangement suitable for this purpose primarily allows the evaluation with a time-independently exponentially decaying weighting when two process variables are logically combined so that the result becomes independent of the process speed. Attenuation factor and decay constant can be adjusted in this method.