Defining the system links between the vehicle on-board computer system and the ground-based computer system

Today trainline information and maintenance information from built-in test equipment is being stored digitally on board the train. Down-loading this information from the on-board system into a lap top computer carried to the train has been the most often chosen method for retrieving and transferring such data to other locations. More timely methods are available that allow direct transfer of information from the vehicle on-board computer system to the ground-based computer system. This paper describes various options open to the designer and explains how one authority chose their particular on-board computer to ground-based computer system link. The discussion is highlighted by reference to the experience gained defining hardware and software and solving interfacing problems for a new ground-based maintenance system being designed for a system