Track circuit communications
View Patent ↗An overlay track circuit is used to transmit information through a block of railroad tracks. In one embodiment, one of a plurality of codes assigned to a receiver/transmitter pair are used to represent each information segment (which may be one or more bits) of an information signal. In another embodiment, bits of the information signal are transmitted between periodic repetitions of a code associated with the transmitter/receiver pair. The modulation may be performed using a frequency shift key technique. Track circuits may be connected to relay information between adjacent blocks of track.
1. A method for communicating digital data through a block of railroad track using an overlay track circuit comprising the steps of:
inputting by a track circuit transmitter connected to one end of a block of railroad track a digital information signal;
selecting by the track circuit transmitter one of a plurality of multi-bit codes for each information segment of the digital information signal, each of the plurality of multi-bit codes for each information segment of the digital information signal being different from multi-bit codes used by adjacent track circuits, wherein the digital information signal has at least two unique portions and wherein at least two unique multi-bit codes are selected by the track circuit transmitter;
modulating by the track circuit transmitter each of the multi-bit codes onto a carrier signal and transmitting the carrier signal through the block of railroad track to a receiver connected to a second end of the block of track;
demodulating by the receiver each of the multi-bit codes;
decoding by the receiver the multi-bit codes to recover the digital information signal; and
outputting by the receiver the digital information signal.
2. The method of claim 1 , wherein the codes are modulated onto the carrier signal using a frequency shift key technique.
3. The method of claim 1 , wherein the information segment of the digital information signal is a single bit.
4. The method of claim 1 , wherein the receiver outputs the digital information signal to a second track circuit transmitter for an adjacent block.
5. The method of claim 1 , wherein the receiver outputs the digital information signal to a wayside device.
6. The method of claim 5 , wherein the wayside device is a railroad track switch.
7. A system for communicating digital data through the rails of a railroad track comprising:
a track circuit transmitter connectable to one end of a block of railroad track, the track circuit transmitter configured to input a digital information signal, select one of a plurality of multi-bit codes for each information segment of the digital information signal, modulate each of the multi-bit codes onto a carrier signal, and transmit the carrier signal through the railroad track; and
a track circuit receiver connectable to a second end of a block of railroad track, the track circuit receiver being configured to receive the carrier signal via the railroad track, demodulate each of the multi-bit codes, decode the multi-bit codes to recover the digital information signal, and output the digital information signal;
wherein each of the plurality of multi-bit codes for each information segment of the digital information signal is different from multi-bit codes used by adjacent track circuits.
8. The system of claim 7 , wherein the codes are modulated onto the carrier signal using a frequency shift key technique.
9. The system of claim 7 , wherein the information segment of the digital information signal is a single bit.
10. The system of claim 7 , wherein the receiver outputs the digital information signal to an output port connectable to a second track circuit transmitter connectable to an adjacent block of railroad track.
11. The system of claim 7 , wherein the receiver outputs the digital information signal to a wayside device.
12. The system of claim 11 , wherein the wayside device is a railroad track switch.