A management system using Global Positioning System receivers for tracking remote units from a central office and quickly and conveniently determining if those remote units have varied from a set of predetermined parameters of operation. The characteristics and the number of plates available are such as to meet the variation requirements made by the various users. The sharing of preamble signaling, elimination of multiple inter-frame gaps or spaces, and the use of a legacy signal field permits a representative embodiment of the present invention to more effectively use a shared communication medium, while in addition providing backward compatible support for legacy network stations.