A method and system for automatically activating a train warning device that uses a positioning system such as a global positioning system receiver or an inertial navigation system to determine the train’s position. A gateway unit is provided that will interconnect a ATM based accesscore network to an IP based. In many current communications systems with frame headers and pilot symbols, the phases of frame headers and pilot syrnbols are not designed to be aligned with any constellation points of the modulated data from the frame body.