A hydraulic system for controlling a belt-driven conical-pulley transmission. The gateway device includes a communications client program to enable client-server communications between the gateway device and a remote communications server via the wide area network using a presence and networking message protocol. The first point being the root of one gear tooth meshing with the tip of the opposite gear tooth creating an initial first contact point and a subsequent second point along the profile when the teeth are disengaging at the first point and engaging at the second point, forming a sealed area, allowing the fluid to hydrostatically escape between the points. The holographic data storage device is capable of effectively reducing a dc term having a bad influence on the characteristics of recording data, minimizing the size of a data unit, that is, a spot, and thus enhancing the density of recording data.