Filtering of impulse noise from laser sensor signals in the process of non-contact thickness measurement in a stainless steel sheet production line

The filtering of noise in data coming from measuring systems in the production environment is an area worthy of special attention. In this article we will introduce the detection and elimination of impulse noise in a series of time measurements adapting techniques of median based filters. First of all, we will describe the impulse noise phenomenon, more important when a sensor pair is considered, and analysed the problems associated with the application of these techniques in a series of time measurements. Subsequently we will develop and apply a progressive iterative method for the detection and elimination of impulse noise, that obtains more than acceptable results, overcoming problems normally associated with these types of filters.