Process for identifying a specific light signal used in a linear optical sensor of goniometer from among other potentially disturbing light signals

A process for identifying a light signal used in a linear optical sensor of a goniometer, of a type used for measuring angles characteristic of wheels of a motor vehicle, in which the light signal is produced by a light beam having a predetermined direction with respect to which an angle to be measured is measured, the angle being formed between the direction of the light beam and a reference axis of the goniometer which reference axis is perpendicular to the linear optical sensor, the linear optical sensor being constituted by a plurality of contiguous and aligned photo-sensitive elements, by means of which elements an image of the light signal can be read, which image is constituted by an ordered totality of intensities of incident radiations recorded on the photo-sensitive elements, a measurement of the angle being a direct function of a distance of the image from an origin for measurement of distances in longitudinal direction defined by an intersection of the reference axis with a longitudinal axis of the sensor, comprising the steps of:

• reading of at least two images at known and different times;
• comparing of the at least two images;
• data processing of data which emerges from the comparing of the at least two images by means of a process aimed at defining environmental disturbance, and making the environmental disturbance distinguishable from the light signal and vice versa;
• wherein an emission of the light signal originating from the light beam is intermittent and has a constant or approximately constant frequency;
• at least two images being read at a time interval determined according to a period of emission of the light signal, and
• wherein at least one of the readings of the images is done in controlled or known conditions of environmental disturbance by using a calibration operation so as to define a template which is stored and used for comparison with other:
• images obtained during use of the process.