Compact Extended Ephemeris Package for GNSS
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Solution Overview
Problem
Current methods for transmitting and processing extended satellite ephemeris data for navigation systems face challenges in reducing data size while maintaining accuracy and minimizing computational load, leading to impractical bandwidth and resource usage on client devices.
Innovation Solution
The method employs curve fitting and interpolation techniques to compress long-term satellite orbit trajectories into a compact ephemeris package using orthogonal basis functions, differential compression, and adjusting numerical precision to minimize data transmission and storage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional broadcast ephemeris is used for GNSS positioning, then position accuracy can be maintained, but data transmission time becomes unacceptably long due to low data rates
Solution Approach 1:
The patent pre-computes extended ephemeris data for future time periods and stores it in an extended ephemeris database before it is needed. This allows the GNSS receiver to immediately retrieve pre-computed satellite position information without waiting for slow broadcast decoding, thus reducing Time To First Fix while maintaining position accuracy through the use of pre-calculated orbital parameters and perturbation coefficients
2Productivity
If extended ephemeris data is transmitted to reduce transmission time, then data transmission efficiency improves, but data size and storage requirements increase significantly
Solution Approach 1:
The patent extracts and transmits only the essential extended ephemeris parameters (Keplerian elements, perturbation coefficients, and validity period information) while leaving the computationally intensive force model and detailed orbital propagation calculations to be performed locally by the GNSS receiver. This selective extraction reduces transmitted data size while still enabling the receiver to generate accurate extended ephemeris predictions
Solution Approach 2:
The patent introduces an extended ephemeris database as an intermediary component that stores pre-computed orbital parameters and perturbation coefficients. This database acts as a local repository that the GNSS receiver can query to obtain extended ephemeris data without requiring continuous transmission of large datasets, thus reducing both transmission bandwidth requirements and immediate storage demands
3Measurement precision
If comprehensive perturbation parameters are used to maintain orbit accuracy, then orbital model precision improves, but computational load on client devices increases
Solution Approach 1:
The patent segments the ephemeris data into two parts: essential parameters (Keplerian elements and perturbation coefficients) that are transmitted and stored in the extended ephemeris database, and the force model with detailed perturbation calculations that remain on the server side. The GNSS receiver only performs lightweight calculations using the transmitted parameters, significantly reducing computational load while maintaining orbital accuracy through the preserved perturbation coefficients
Data Source
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AI summary
A method and apparatus are presented for providing a compact extended ephemeris package for GNSS processing. An extended ephemeris service provides orbit trajectories and clock corrections which are predicted into the future for navigation satellites. The extended ephemeris package format used allows the ephemeris information to be sent quickly and efficiently, even when using a low bandwidth communication network. Client GNSS receiver devices obtain the extended ephemeris package and extract the satellite ephemeris information for later use. This allows a client device to operate for many days or weeks without needing to decode or receive new satellite ephemeris information.