Adaptive Synthetic Positioning Using Dead Zone Database
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Solution Overview
Problem
GNSS receivers face challenges in providing accurate positioning when entering or exiting a blocked area, such as a tunnel, where satellite signals are unavailable, leading to a need for methods and systems that minimize resource drain and complex calculations.
Innovation Solution
A portable device with a GNSS receiver uses a dead zone database to retrieve polynomial coefficients, calculating synthetic position solutions during the blocked area and improving position accuracy upon exiting, by modeling the travel path through the use of cubic polynomial equations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If polynomial coefficients are retrieved from dead zone database and synthetic position solutions are calculated, then position accuracy in and near dead zones is improved, but device computational resources and energy consumption increase
Solution Approach 1:
The system pre-calculates and stores polynomial coefficients in a dead zone database during periods when GNSS signals are available. When entering a dead zone, the receiver retrieves these pre-computed coefficients and applies them to generate synthetic position solutions, avoiding the need to perform complex calculations in real-time during signal denial periods.
Solution Approach 2:
The system creates a mathematical model (polynomial representation) of the receiver's trajectory through the dead zone based on positions recorded before entering the dead zone. This copied trajectory model is then used to generate accurate position estimates during the dead zone without requiring actual GNSS measurements or heavy computational resources.
2Measurement precision
If complex calculations are performed to model travel path through blocked area, then position solutions upon exiting dead zone are improved, but device processing complexity increases
Solution Approach 1:
The system transforms the complex problem of modeling three-dimensional trajectory through a dead zone into a simpler polynomial fitting problem. By changing the mathematical representation from raw coordinate data to polynomial coefficients, the system reduces processing complexity while maintaining position accuracy when exiting the dead zone.
Solution Approach 2:
The system creates a simplified mathematical copy of the receiver's path through the dead zone using polynomial equations. This copied path model requires minimal processing to evaluate and can be quickly applied when the receiver exits the dead zone, avoiding the need for complex real-time calculations.
3Measurement precision
If dead zone database is used to store polynomial coefficients, then positioning in blocked areas is improved, but memory resources are consumed
Solution Approach 1:
The system extracts only the essential information needed for dead zone positioning—polynomial coefficients that define the trajectory model—from the full set of GNSS measurement data. By storing only these compressed coefficient representations rather than raw position data, the system minimizes memory consumption while retaining the ability to generate accurate synthetic positions.
Data Source
AI summary
Methods, systems, and portable devices capable of adaptive synthetic positioning while in a dead zone are described. In one method, when a portable device having a Global Navigational Satellite System (GNSS) receiver and a dead zone database enters a dead zone, it determines whether the dead zone database has a record for the dead zone. If it does, it retrieves parameters corresponding to the dead zone from the database and calculates synthetic position solutions using the retrieved parameters while in the dead zone. The portable device may also use the synthetic position solutions to help calculate position solutions when exiting the dead zone. If a dead zone database record does not exist, the portable device determines parameters for calculating synthetic position solutions in the dead zone and a new dead zone database record indicating a set of parameters based on the determined set of parameters is created.