I never said GPS gave or was used to determine weight length etc, I said there are other ways of transmitting location, speed ,and direction, those factors are included in the whole process of determining ( on the back end by the central processors) how far each train has to be away from one another to stop before an interlocking or signal. My notes on OUR system don't use wireless signals to talk to the train, (why would they it would mean a whole lot of extra processing to occur in the loco) as they talk to a central controller that then gives the proper info to the loco or propulsion part of the consist. There is a lot more going on in the back ground then just radio signals going back and forth. You have type of track, what speed can it handle, how tight are bends in track, and how far between interlockings/signals, the train operator may or may not have to input number of cars, gross weight and other parameters, or it may already be inputted before departure for the central controller to determine route and speed.
As far as signals being wireless, they don't have to be to work within PTC. All I said was they could also be wireless to cut maintenence AND be tied into PTC. Suppose a loco from another RR goes into this territory and they don't use your example of signals to train. Hows that going to work?
From the sounds of information being expressed here this is my main concern about PTC, there is NO standard, and with each RR doing something different it could cause problems.