Patent ID: 7639181

Claim:
In a navigational system utilizing a plurality of satellites that transmit radio-frequency signals containing time and orbit information of said satellites, wherein said radio-frequency signals are severely attenuated when received at a receiver, a method of obtaining a position solution of the receiver from a received attenuated radio-frequency signal comprising: strengthening said received attenuated radio-frequency signal, wherein strengthening said received attenuated radio-frequency signal comprises coherently integrating, over an extended interval of time, correlations between said received attenuated radio-frequency signal and locally generated signal replicas to produce extended-interval correlations, the extended-interval correlations produced based on dynamically estimated data bit edges and data bit signs; maintaining lock onto said received attenuated radio-frequency signal, wherein maintaining lock comprises performing error discrimination based on said extended-interval correlations; and obtaining a position solution of the receiver based on time, frequency, and data bits extracted from said received attenuated radio-frequency signal.