Regional Correction Information for Satellite Positioning Accuracy
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Solution Overview
Problem
Existing positioning systems using navigation satellite system (NSS) signal codes suffer from limited accuracy due to atmospheric distortions, and carrier phase measurements, while more precise, are ambiguous and require resolution to achieve centimeter-level or millimeter-level precision.
Innovation Solution
The method involves obtaining satellite orbit and clock error information, estimating ambiguities in carrier phase signals at reference stations, predicting satellite orbits and clock errors, and calculating residual errors to redefine satellite clock errors, which are then broadcast for use in positioning solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If code-based positioning using GPS C/A code is used, then the positioning system is simple and publicly accessible, but the positioning accuracy is limited to approximately 15 meters
Solution Approach 1:
The patent introduces a correction information system as an intermediary between the GPS satellites and receivers. This system collects data from reference stations, processes it to generate correction information, and transmits this information to users. The correction information acts as a mediator that bridges the gap between the simple code-based system and the need for higher accuracy, enabling improved positioning without requiring complex hardware changes at the receiver end.
2Measurement precision
If carrier phase measurements are used for positioning, then positioning precision can reach centimeter-level or millimeter-level, but the carrier phases are ambiguous by an unknown number of cycles requiring resolution
Solution Approach 1:
The patent extracts the ambiguity resolution problem from the individual receiver processing and relocates it to the correction information generation system. By collecting carrier phase measurements from multiple reference stations and processing them centrally, the system resolves ambiguities at the source before distributing correction information to users. This extraction of the complex processing task from end-user devices significantly reduces the complexity burden on individual receivers.
Solution Approach 2:
The system performs preliminary ambiguity resolution by processing carrier phase measurements from reference stations before generating correction information. By resolving the integer ambiguity problem in advance during the correction information generation phase, the system eliminates this computational hurdle before the correction data is transmitted to users, allowing them to achieve high-precision positioning without implementing complex ambiguity resolution algorithms themselves.
3Area of stationary object
If wide area satellite orbit and clock error information is used, then the coverage area is large, but the information may not account for regional variations in atmospheric conditions
Solution Approach 1:
The patent implements local quality by establishing reference stations at specific geographic locations that collect local atmospheric data. These reference stations measure carrier phase and code measurements at their particular locations, capturing regional atmospheric characteristics. The correction information generated from these local measurements inherently reflects the local quality of atmospheric conditions, allowing the system to provide regionally-optimized corrections while maintaining wide area coverage through the network of distributed reference stations.
Data Source
AI summary
The invention relates to methods for providing information for use by a navigation satellite system (NSS) receiver and/or processing entity receiving data therefrom, for positioning purposes. In one embodiment, satellite orbit information and satellite clock error information applicable over a wide area and to epoch t1 is obtained (s10) for each of a plurality of NSS satellites. Ambiguities in the carrier phase of NSS signals received at epoch t1 at narrow area reference stations are estimated (s20). For each satellite, the satellite orbit and satellite clock error at epoch t2 are predicted (s30). A residual error for modelling errors having a common or substantially common line-of-sight dependency is estimated (s40a). The residual error is added (s50a) to the predicted satellite clock error to form a redefined satellite clock error. The invention also relates to variants of the above-mentioned method, and to systems, computer programs, and computer program products.