Method for using external constraints to improve the speed and reliability of phase ambiguity resolution in real-time kinematic initialization

摘要

A method for obtaining integer ambiguity solutions based on externally provided constraints, e.g., altitude. Such constraints are useful in reducing the computational burden created by the search problem, and using constraints is particularly more effective when a more limited number of satellite vehicles are visible than is ordinarily the case. The constraints are exercised in a search algorithm. As the branches of the integer ambiguity search tree are traversed, an additional test is used to determine if the current search candidate is compatible with such external constraint. Because a three-dimensional position is associated with each search candidate, the branch clipping is straightforward. The ambiguity candidates are each only acceptable if their locations in space are within a confidence region bound set determined from the external constraint. Any sensor that can provide any combination of x, y, or z position information that is better than that obtainable from GPS code phase is a candidate source of such external constraints.