System and method for using parabolic models to improve position estimates from a global positioning system

A method for using parabolic models to improve an accuracy of a position estimate based on actual pseudoranges derived from satellites of a global positioning system, the method comprising the steps of:

• determining a plurality of actual pseudoranges corresponding to each of a plurality of satellites in view of a reference antenna;
• constructing, for each satellite, a parabolic model from said corresponding plurality of actual pseudoranges;
• extrapolating an estimated pseudorange for each satellite at a future time from said corresponding parabolic model;
• computing a parabolic bias for each satellite based on a corresponding actual pseudorange determined at said future time and a corresponding estimated pseudorange;
• and
• using said parabolic bias from each satellite to improve the accuracy of the position estimate.

A system for improving the accuracy of a position estimate based on pseudoranges derived from a global positioning system, the system comprising:

• first means for determining a plurality of reference pseudoranges corresponding to each satellite in view of a reference antenna at consecutive times over a time period, said plurality of reference pseudoranges each representing a distance between said reference antenna and a corresponding satellite over said time period;
• second means, responsive to said first means, for constructing a parabolic model for each satellite based on said corresponding plurality of reference pseudoranges;
• and
• third means, responsive to said first means and said second means, for computing a first spatial bias for each satellite, said spatial bias being a difference between an extrapolated pseudorange determined from said parabolic model and a future pseudorange derived after said the time period;
• fourth means, responsive to said first means, for computing an estimated position of said reference antenna using said plurality of reference pseudoranges;
• fifth means, responsive to said second means, for comparing said estimated position with a known position of said reference antenna to derive a second spatial bias;
• and
• sixth means for determining a position estimate of a user, for receiving said first and second spatial biases, and for using said first and second spatial biases to improve said terrestrial position estimates.