A process for operating an exhaust gas treatment device in a gasoline engine which is operated mainly with a stoichiometric airfuel ratio and is operated with a rich-mix airfuel ratio when accelerating or under full load. Short optical pulses are first modulated with data, then dispersed in time so that they spread out over multiple bit periods, then the desired code is applied to the dispersed pulses. Portability is enhanced by an optional free-standing roller base. Consequently, the present invention has the effect of accomplishing the reduction in size of the battery system, reducing influences caused by external conditions, decreasing noise, and effectively controlling the optimum operating temperature of the battery pack. The method optionally includes rendering processed image data for the output scanline to a rendering device.