The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 20, 1976
Filed:
Mar. 27, 1975
John H Auer, Fairport, NY (US);
Willis R Smith, Johannesburg, ZA;
General Signal Corporation, Rochester, NY (US);
Abstract
There is disclosed a double rail track circuit for use within a railroad block or each cut section of a block. Adjacent cut sections, or blocks, are separated by insulated rail joints. A transmission line having terminals accessible at each joint is provided. The transmission line has impressed thereon a modulated carrier signal to provide a reference signal at the modulation frequency. The reference signal derived from the carrier is coupled to one end of each block, or cut section, in such a manner that the signals of adjacent blocks, or cut sections, are out of phase with respect to each other. A synchronous detector is coupled between the transmission line and the rails at the other end of the block, or cut section, to compare the phase of the signal at the other end, with the anticipated signal phase. Band-pass filters may be used between the rails and the synchronous detector and between the transmission line and the synchronous detector and which do not pass common frequencies. The system is less subject to interference from inductive coupling from power lines and/or from propulsion currents in the rails than systems employing a reference signal applied directly to a transmission line and coupled to the rails.