GNSS signal processing methods and apparatus with ambiguity selection

Abstract

Methods and apparatus are provided for estimating parameters, i.e. ambiguities, derived from GNSS signals. Observations of a GNSS signal from each of a plurality of GNSS satellites are obtained (4120). The observations are fed to a filter having a state vector at least comprising a float ambiguity for each received frequency of the GNSS signals, each float ambiguity constituting a real number estimate associated with an integer number of wavelengths of the GNSS signal between a receiver of the GNSS signal and the GNSS satellite from which it is received, and the filter being for estimating a float value for each float ambiguity of the state vector (4140). A subset of float ambiguities of the state vector is selected (4150). Integer values are assigned to the estimated float values of the float ambiguities of the subset to define a plurality of integer ambiguity candidate sets (4160). A quality measure is determined for each of the candidate sets. A weighted average of the candidate sets is formed (4200). 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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