AUTOMATIC CHANGEOVER SYSTEM FOR COMMUNICATION NETWORKS WHICH CHANGES OVER FROM ONE COMMUNICATION NETWORK TO ANOTHER, AN AUTOMATIC CHANGEOVER STATION FOR THE SAME AND AN AUTOMATIC CHANGEOVER METHOD OF COMMUNICATION NETWORKS

An automatic changeover method of communication networks includes steps (a) to (d). In the step (a), a first station communicates with a second station through a first wireless communication network. In the step (b), the first station measures a first level fluctuation value more than once, wherein the first level fluctuation value indicates a fluctuation degree of electric field intensity of an electromagnetic wave received from the first wireless communication network. In the step (c), the first station calculates a first average level fluctuation value, wherein the first average level fluctuation value is an average of a plurality of the first level fluctuation values. In the step (d), the first station changes over from the first wireless communication network to a second wireless communication network based on the first average level fluctuation value. The first wireless communication network may be a network for a wireless LAN (Local Area Network), and the second wireless communication network may be a network for a PHS (personal Handyphone System).