US 8,542,146 B2 · Generalized partial fixing

Abstract

Described is a generalized approach for integer parameter estimation, especially in the context of Global Navigation Satellite Systems (GNSS). The problem solved is the case where a definitively correct integer solution cannot be identified for all ambiguity parameters in a reliable way. The proposed solution is to apply a linear transformation to the ambiguities (multiply with a matrix) such that the images of the first and the second candidate (or more) are identical. That way, from the first and second (and possibly more) candidates of the integer least-squares solution, a subset of ambiguity combinations is derived that can be fixed. Thus, it is no longer necessary to choose between the solutions as they coincide for the new ambiguities. The advantage of this approach is maximizing all information still available when finally deriving additional parameters such as position, clock error, atmospheric errors and/or time correlated noise. This technique is applicable to real-time and post-processing applications, as well as to pure GNSS applications, GNSS integrated with other sensors (e.g. INS) and other applications that have to resolve multiple integer ambiguities. This may also apply to optical distance-measurement. GNSS applications include kinematic and static positioning with single base stations as well as with multiple base stations or reference station networks. They also comprise the integer parameter estimation methods used within the reference station network computations.

Claims21

Dependent claims

A method of operating a system comprising at least one processor and memory with instructions for estimating integer ambiguities from carrier phase observations of GNSS signals received at multiple stations from at least four satellites, comprising:

a. determining from the carrier phase observations a ranked plurality of candidate sets of estimated integer ambiguities,
b. applying a criterion to select a first candidate set of the ranked plurality of candidate sets as a selected candidate set,
c. forming a matrix G such that the image formed when matrix G is linearly combined with the selected candidate set is equal to the image formed when matrix G is linearly combined with a second candidate set, and
d. applying the matrix G to the selected candidate set to determine a modified candidate set of estimated integer ambiguities.

1 more element

Apparatus for estimating integer ambiguities from carrier phase observations of GNSS signals received at multiple stations from at least four satellites, comprising a processor and a set of instructions enabling the processor to:

a. determine from the carrier phase observations a ranked plurality of candidate sets of estimated integer ambiguities,
b. apply a criterion to select a first candidate set of the ranked plurality of candidate sets as a selected candidate set,
c. form a matrix G such that the image formed when matrix G is linearly combined with the selected candidate set is equal to the image formed when matrix G is linearly combined with a second candidate set, and
d. apply the matrix G to the selected candidate set to determine a modified candidate set of estimated integer ambiguities.

1 more element

Dependencies are inferred from the claim text.

Generalized partial fixing

Life of this patent

Generalized partial fixing

Life of this patent

Abstract

Claims21