Patent ID: 6219385
Filing Date: 2001-04-17
Classification: H04L

Abstract:
For use in the environment of a plurality of digital AM and FM (AM/FM) radio stations, a digital positioning system using said digital AM and FM radio stations comprising:a reference station which regularly and passively receives signals from all local digital AM/FM stations and measures variations in key parameters of frequency and wavelength thereof and provides AM/FM correctional data signals corresponding to each digital AM/FM station frequency and wavelength variation to a a common facility,said reference station center being adapted to provide said AM/FM correctional data signals to each of said digital AM/FM radio stations for insertion into ancillary digital data broadcast from each digital AM/FM radio station,a plurality of mobile receivers in said environment of digital AM/FM radio stations, each said mobile receiver receiving and processing three or more AM and/or FM signals and estimating and updating its position at periodic intervals and communicating the results thereof to said common facility via cellular or other PCS or digital network in accordance with the emergency protocol service of the receiver.