Improvement in linearity is achieved at low costs in a power amplifier module employing an envelope tracking system. The pre-coated aluminum sheet is used for the heat sink for onboard LED lighting, and is the pre-coated aluminum sheet including an aluminum sheet and a resin-based film. The master device sends the trigger signal via the TRACK channel before data transmission begins. The protective pad includes a folding stitch line to enable the crisp folding of the pad around entranceway corners. The proposed monitoring system and method provide accurate control of target dimensions, while optimizing the adjustment of other quality related parameters such as faces parallelism and cant centering, as well as to measure the level of some surface defects generated at cutting such as knife marks, stripping and roughness, in order to obtain a more complete performance diagnostic.