Patent ID: 6211781
Filing Date: 2001-04-03
Classification: G01S,G06Q,G07B,G07C

Abstract:
A method for determining a location of a moveable article, comprising:transmitting an interrogation signal;receiving the interrogation signal in the article;transmitting a response signal from the article, the response signal providing a unique identification code;receiving the response signal using at least one of a plurality of receivers, each receiver having a unique receiver code;generating an information signal providing the identification code and the corresponding receiver code;repeating the steps of transmitting and receiving the interrogation signal, transmitting and receiving the response signal, and generating the information signal to generate a plurality of information signals;recording the plurality of information signals in real-time over a period of time;tracking the location of the article in real-time;comparing the tracked location of the article with a predetermined route; andgenerating an error signal when the tracked location deviates from the predetermined route.