GPS Positioning Altitude Dispersion Multipath Error Correction
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Solution Overview
Problem
In GPS positioning systems, multipath environments with high building density lead to inaccurate position calculations due to varying satellite signal reception, as existing methods fail to differentiate between satellite sets effectively, resulting in inconsistent positioning accuracy.
Innovation Solution
A method that selects satellite sets, calculates candidate positions, determines the reception environment based on the dispersion of altitudes, and evaluates positions using an environment-specific evaluation method to select the most accurate position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a unified evaluation method is used for all satellite sets, then the evaluation process is simple, but positioning accuracy deteriorates in multipath environments
Solution Approach 1:
The patent applies local quality by determining the reception environment type (multipath or open-sky) for each satellite set individually based on altitude dispersion, and then applying different evaluation methods accordingly. This allows the evaluation process to adapt to local characteristics of each satellite set rather than using a uniform approach, thereby maintaining high positioning accuracy in multipath environments while keeping the overall process manageable.
Solution Approach 2:
The patent changes the evaluation parameter based on the reception environment type. For multipath environments, the evaluation uses altitude dispersion as a key parameter to identify and exclude inaccurate satellite sets. For open-sky environments, a different evaluation approach is used. This parameter change allows the system to optimize positioning accuracy for different environmental conditions without requiring a completely complex unified system.
2Device complexity
If satellite sets are evaluated using open-sky evaluation methods in multipath environments, then the evaluation method remains simple, but positioning accuracy deteriorates
Solution Approach 1:
The patent applies dynamics by making the evaluation method adaptive rather than static. The system dynamically determines which evaluation method to use based on the reception environment type identified through altitude dispersion analysis. This dynamic switching between evaluation methods allows the system to maintain simplicity in each individual method while achieving high accuracy across different environments through intelligent selection.
3Measurement precision
If altitude dispersion is used to determine reception environment, then positioning accuracy improves in multipath environments, but calculation complexity increases
Solution Approach 1:
The patent applies preliminary action by calculating altitude dispersion for each satellite set as a preparatory step before the main positioning evaluation. This preliminary calculation of altitude dispersion allows the system to classify reception environments and select appropriate evaluation methods in advance, reducing the overall calculation complexity during the main positioning process while maintaining high accuracy in multipath environments.
Data Source
AI summary
A reception environment is determined to be a multipath environment when the difference (positioning altitude difference) between the maximum value (maximum altitude) and the minimum value (minimum altitude) of the altitudes of candidate present positions P of respective satellite sets exceeds a given threshold value (e.g., 200 m), and is determined to be an open-sky environment when the positioning altitude difference is equal to or less than the given threshold value. When the reception environment is the open-sky environment, an evaluation point E of each satellite set is calculated using a known evaluation method based on the number of satellites, a PDOP value, and the like. When the reception environment is the multipath environment, the evaluation point E of each satellite set is calculated in the same manner as in the open-sky environment, and a change amount ΔE corresponding to the difference (altitude difference) between the altitude corresponding to the preceding located position acquired from an altitude table and the altitude of the candidate present position of the target satellite set is subtracted from the evaluation point E.