Coded Track Circuits and Their Application on Railway Signalling

The coded system was initially evolved to devise a suitable apparatus for railway signalling, the receiving equipment in the engine has to pick up the inductive energy from the track. A.C. voltages were initially superimposed on d.c. track circuits and later on the development of a.c. coded track circuits was made.The present paper deals with various types of coding transmitters and their corresponding receivers with accessories; schematic explanation is being afforded by the line diagrams.The chief advantage of coded track circuit over the conventional d.c. track circuits presently employed in Indian Railways is that the application of coded track circuits does away with the requirement of the line wires for the control of the multiple aspects and the lengths of the track circuits are increased without affecting the efficiency of performance.