Patent Document ID: 4791572
Application ID: 06801612
Patent Status: 1

Claim One:
1. A method for displaying positional data on a map of a geographical area including the steps of: producing a digitized street or terrain map consisting of digitized data and inputting said digitized data into a computer provided with a display screen, said computer provided at a central station; determining the actual geographical coordinates of a plurality of reference monuments; producing a table of geographical reference coordinates based upon the geographical coordinates of said reference monuments and inputting this map into said computer, said table of geographical reference coordinates referenced to said digitized street or terrain map; producing a table of positional data based upon first actual time delay signals generated by a navigational tracking system and received by said plurality of reference monuments, said first actual time delay signals received by said reference monuments being transmitted to said central station computer at said central station, said central station computer producing a derived set of coordinates of each of said reference monuments based upon said first actual time delay signals; comparing the actual geographical coordinates of said reference monuments with the derived set of coordinates and determining a first correction factor based upon the difference of said actual and said derived set of coordinates; updating said table of positional data utilizing said first correction factor derived in said comparing step; determining a relative position of a plurality of vehicles in said geographical area by comparing the derived position coordinates of each of said vehicles generated by the receipt of second actual time delay signals from the navigational tracking system by each of said vehicles and the transmission of said second actual time delay signals from each of said vehicles to said central station computer with the actual position coordinates of each of said vehicles, and determining a second correction factor based upon the difference of said actual and said derived set of coordinates; producing a transparent map layer utilizing said second correction factor derived in said immediately preceding step; receiving, at said central station, vehicular positional information generated by the navigational tracking system for at least one vehicle to be tracked; and displaying said vehicular positional information on said digitized street or terrain map.