Two-stage interacting multiple models filter for use in a global positioning system

An apparatus for determining a dynamical quantity of a host receiver of signals conveying information useful in estimating the dynamical quantity, the apparatus comprising:

• a) means for providing a single-point solution, by solving for the dynamical quantity of the receiver using a single-point solution having as an input the information useful in estimating the dynamical quantity being determined;
• b) means for providing a plurality of filter solutions each assuming a different motion model for the receiver;
• and
• c) means for combining the plurality of filter solutions to provide a first value of the dynamical quantity based on weights that take into account the likelihood of the suitability of each motion model, with the likelihood determined on the basis of agreement of the first value of the dynamical quantity compared with a second value of the dynamical quantity as indicated by a single-point solution.

A system for determining a dynamical quantity of a component receiver of signals conveying information useful in estimating the dynamical quantity, the system comprising:

• a receiver, including:
• a) means for providing a single-point solution, by solving for the dynamical quantity of the receiver using a single-point solution having as an input the information useful in estimating the dynamical quantity being determined;
• b) means for providing a plurality of filter solutions each assuming a different motion model for the receiver;
• and
• c) means for combining the plurality of filter solutions to provide a first value of the dynamical quantity based on weights that take into account the likelihood of the suitability of each motion model, with the likelihood determined on the basis of agreement of the first value of the dynamical quantity compared with a second value of the dynamical quantity as indicated by a single-point solution.