Gnss signal processing methods and apparatus with tracking interruption

Abstract

Methods and apparatus are provided for estimating parameters, i.e. ambiguities, derived from GNSS signals. Observations of each of received frequencies of a GNSS signal from a plurality of GNSS satellites are obtained for a plurality of instances in time (3120). The time sequence of observations is fed to a filter to estimate a state vector comprising float ambiguities, wherein each float ambiguity constitutes a non integer estimate of an integer number of wavelengths for a received frequency of a GNSS signal between a receiver of the GNSS signal and the GNSS satellite from which it is received and wherein the float ambiguities of the state vector are updated over time on the basis of the observations (3140). The occurrence of an interruption in tracking of at least one signal of a satellite is determined (3121). The float ambiguity of the state vector for the at least one signal for which an interruption in tracking occurred is maintained at the value before the interruption in tracking occurred (3122). Integer values are assigned to at least a subgroup of the estimated float values to define a plurality of integer ambiguity candidate sets (3160). A quality measure is determined for each of the candidate sets. A weighted average of the candidate sets is formed (3200). 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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