...
The figure bellow, show the various systems that are in use.
...
In this case, a Cisco 819 router is deployed in each of the trains on the transit system.
The router, using over 3G, allow to report to ruban in realtime the current train position. Also, on the router a script is running to allow to inform RuBAN what is the GTFS trip the train is on.
With this information, the ETA module calculate for all the stops on the given trip, what is the estimated arrival time for this train.
The ETA module also, over-time, learns what the ETAs is and so refined its predictions.
In order to made the ETA information available to the public, and so displayed in signs located on each station, the ETA module convert it to a format that a DVS system understands.
Its then the DVS system that sends this information to the signs on the stations.
...