US Patent 7577502 Proximity detection and communication mechanism and method

A vital proximity detection mechanism and method for reliably determining and communicating the position of a railroad switch point relative to a normal fixed track and a reverse fixed track, wherein the mechanism includes substantial component redundancy and fault-checking features and otherwise meets promulgated safety standards for vital componentry. The mechanism includes an RF transmitter and remote status indicator unit to allow for remote adjustments of proximity sensors while monitoring the effects of such adjustments.