Cable modems are provided for measuring a noise signal power level on the upstream side of the cable network. The semiconductor device having the Schottky junction includes a semiconductor substrate of a first conductivity type. By telescoping the arms to adjust their length, and adjusting the angles of the arms, connection points on the arms may be positioned so that the universal flat panel display mounting system may work with flat panels in different VESA size categories or for flat panel displays that don’t conform to the VESA standard.