An electronic control unit of an internal combustion engine computes a remaining combusted gas amount Megr1, which exists in a cylinder immediately before an intake valve is opened, based on an intake pipe pressure Pm, an engine speed NE, and an intake valve opening timing Topen. The method and apparatus accomplish this by separating the functions of data acquisition from those of processing and imaging, and by connecting the data acquisition, processing and imaging components through a communications network, thus permitting the data acquisition, processing and imaging functions to be carried out at disparate locations within said network. At least a portion of each of the plurality of grooves has a shape and orientation determined as a function of the trajectory of the polishing medium during use of the pad. Hereby, an optimisation between high capacity and reliable and correct channel estimation on the basis of the pilot parts can be achieved. The method queries for additional information representing the calling station, and the method presents the telephone number and the additional information to a user at the called station.