Gnss signal processing methods and apparatus with scaling of quality measure

Abstract

Methods and apparatus are provided for estimating parameters, i.e. ambiguities, derived from GNSS signals. Observations of GNSS signals are obtained from each of a plurality of GNSS satellites (1120). The observations are fed to a filter (1140) having a state vector at least comprising a float ambiguity for each received frequency of the GNSS signals. The filter estimates a float value for each float ambiguity of the state vector. Integer values are assigned to at least a subgroup of the estimated float values to define a plurality of integer ambiguity candidate sets (1160). A quality measure is determined for each of the candidate sets. The best quality measure of the candidate sets is determined. An expectation value (1170) of the candidate set having the best quality measure is determined. An error measure as a ratio of the best quality measure to the expectation value is determined. The quality measures of the candidate sets (1180) is adapted as a function of the error measure. A weighted average of a subgroup of the candidate sets on the basis of the adapted quality measures is formed, wherein at least one of selecting the subgroup of the candidate sets and the weighting of each candidate set in the weighted average is based on the adapted quality measure (1200). Ambiguities of the weighted average can be used in subsequent operations to aid in determining a position of the receiver or can be used to prepare data, e.g., in a network processor that can be used to augment position information of a rover.

Description

[0001] related application [0002] This application claims the benefit of US Provisional Patent Application 61 / 189,382, filed August 19, 2008, the contents of which are hereby incorporated by reference. technical field [0003] The present invention relates to position estimation methods and devices, and in particular to such methods and devices based on navigation satellite system signals. Fields of application of these methods and devices include, but are not limited to, navigation, map making, land surveying, civil engineering, disaster prevention and mitigation, and scientific research. Background technique [0004] 1 Introduction [0005] Global Navigation Satellite Systems (GNSS) include the Global Positioning System (GPS) (USA), GLONASS (Russia), Galileo (Europe) and COMPASS (China) (systems in use or in development). GNSS typically uses multiple satellites orbiting the Earth. The plurality of satellites form a constellation of satellites. GNSS receivers detect c...

AI Technical Summary

Problems solved by technology

[0053] However, the practical disadvantage of the floating-point solution is that although it converges, doing so is time-consuming

However, while pinning the ambiguities speeds up the convergence process, this is done at the risk of incorrectly pinning the ambiguities, which can lead to convergence towards the wrong solution

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