Track communication system for continuous rail

Claim 1

A code communication system for continuous rail track layouts including a plurality of center fed track circuits wherein the improvement comprises: I. train occupancy communication means including: a. a plurality of track transmitters each selectively tuned to one of two transmission frequencies alternately coupled to the rails at spaced intervals, for generating signals in the track rails, and said intervals reprEsenting the center of a first set of track circuits; b. a plurality of occupancy receivers each selectively responsive to the transmitter frequencies coupled to the rails at the ends of each of said first track circuits for receiving signals from its associated transmitter; and c. means coupled to the occupancy receivers for generating an occupancy signal when communication is cut off from one transmitter and its associated occupancy receiver by a vehicle shunt, and II. control communication means including: a. a plurality of control transmitters each selectively tuned to one of two transmission frequencies, different from the track transmission frequencies, alternately coupled to the rails at each adjoining adjacent ends of the first track circuits defining a second set of track circuits superimposed on the first set of track circuits in the same stretch of railway track for generating control signals in said rails; b. a plurality of control receivers each selectively responsive to the transmitter frequencies, coupled to the rails at the center of each of the second track circuits for receiving control signals from its associated transmitter, and c. means including the first and second sets of track circuits superimposed one on the other for the same stretch of railway track for activating an occupancy transmitter at a center feed point in each of the first track circuits in response to a control receiver at that point and for activating a control transmitter at the end of each of the first track circuits in response to an occupancy receiver at that point, d. whereby a distinctive control signal can be communicated through the track layout in either direction by cooperation of the first and second track circuits and the control signal can be modified in character by the presence of a train to provide a double direction railway signaling system without requiring the use of wayside line wires for signal control purposes.