Satellite Orbit Parameter Extension Under Ephemeris Saturation

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Solution Overview

Problem

Satellite signal-based positioning systems face accuracy degradation due to the limited validity period of satellite ephemeris data, which can be exacerbated by parameter values becoming saturated, leading to inaccurate satellite position and velocity calculations.

Innovation Solution

A method and apparatus for extending the validity period of satellite orbit parameters by checking for parameter saturation and adjusting the extension process accordingly, using a force model to predict satellite positions and velocities, and reducing the validity time if parameters are saturated.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If the validity period of ephemeris data is extended beyond its intended lifespan, then the availability of positioning is improved, but the positioning accuracy deteriorates due to parameter saturation

Engineering Contradiction:

Improvevalidity period of ephemeris dataVSAvoidpositioning accuracy

Core Design Contradiction:

Duration of action of moving objectVSMeasurement precision

Solution Approach 1:

The system performs preliminary detection of parameter saturation before extending the validity period. By checking whether parameters are saturated prior to extension, the system prevents accuracy degradation while still enabling validity period extension when conditions permit, thus resolving the contradiction between extended availability and maintained precision

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the extension of validity period based on the saturation status of parameters. Rather than applying a fixed extension rule, the system adapts the extension decision to current parameter conditions, allowing validity extension when parameters are not saturated while preventing extension when saturation would compromise accuracy

Inventive Principle:

Principle #15Dynamics

2Loss of time

If parameter values are used beyond their validity period through extension, then the time-to-first-fix is reduced, but the reliability of position calculation deteriorates

Engineering Contradiction:

Improvetime-to-first-fixVSAvoidreliability of position calculation

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The system performs preliminary saturation detection on parameters before allowing validity period extension. This advance check ensures that extension only occurs when parameters remain reliable, thus reducing time-to-first-fix without compromising the reliability of position calculations

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from parameter saturation status to control the extension process. By continuously monitoring whether parameters are saturated and using this information to enable or disable extension, the system maintains reliability while achieving faster time-to-first-fix when conditions allow

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP3559701B1Supporting an extension of a validity period of parameter values defining an orbit

Publication Date: 2025.12.17 HERE GLOBAL BV

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AI summary

An apparatus receives values of parameters defining an orbit of a satellite of a satellite navigation system for a validity period. The apparatus furthermore determines whether a received value of at least one parameter of a predetermined set of the parameters is saturated. The apparatus then takes into account whether a received value of at least one parameter of the predetermined set of parameters is determined to be saturated in a process of extending the validity period of the received values of parameters.