This invention provides a system and a method to automatically switch cellular data communications from 3G to 4G mode wherever reliable 4G cellular connectivity is available, and to collect and report reliable 4G cellular coverage geo-fence polygon information. The interrupt controller comprises an interrupt source interface operable to receive interrupt requests generated by a first plurality of interrupt sources, and a daisy chain interface operable to receive a daisy chain interrupt request output by a further interrupt controller based on a second plurality of interrupt requests generated by a second plurality of interrupt sources. A perforated wearing protection element is mounted on the chisel head. Excellent adhesion is provided between the extruded compliant layer and the image receiving layer by means of the aqueous-coated subbing layer.