Gary B Clark

US Patent:

40748790, Feb 21, 1978

Filed:

Nov 29, 1976

Appl. No.:

5/745703

Inventors:

Gary E. Clark - Henrietta NY
Klaus H. Frielinghaus - Rochester NY
Barry L. Smith - Rochester NY

Assignee:

General Signal Corporation - Rochester NY

International Classification:

B61L 2106

US Classification:

246 37

Abstract:

A track circuit signalling system for an electrified rapid transit system using significantly fewer components is provided. Instead of a transmitter and receiver at each track circuit boundary, alternate boundaries have transmitters only; and the intermediate boundaries have two receivers. The coupling units for the two receivers are more economical than the prior art coupling unit for coupling the transmitter-receiver combination. The transmitters on each side of a receiver pair transmit signals on different carrier frequencies. Each transmitter transmits in both directions from its location. Of the two receivers at a given boundary, one is tuned to respond to signals from the transmitter on one side, while the other receiver of the pair is tuned to respond to signals from the transmitter on the other side. For special applications using overlapping track circuits, selected transmitters may be omitted and a single receiver used on each side of the omitted transmitter.