Satellite Navigation Augmentation Signal Reliability Filtering

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Solution Overview

Problem

Existing GPS positioning systems face accuracy degradation due to low carrier-to-noise power density ratio (C/No) and other errors, leading to potentially dangerous self-position determination for high-speed mobile objects like airplanes, as they fail to adequately assess the reliability of GPS satellite signals.

Innovation Solution

A satellite-based augmentation system that includes a threshold value calculation unit and a pseudorange determination unit to assess the C/No value and determine the reliability of GPS signals, ensuring accurate position calculation by filtering out low-reliability signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If smoothing processing is performed on pseudorange to remove noise, then positioning accuracy is improved, but residual noise remains due to simple processing methods

Engineering Contradiction:

Improvepseudorange accuracyVSAvoidnoise removal effectiveness

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by evaluating the C/No value of GPS satellite signals before performing pseudorange measurement and smoothing processing. By pre-assessing signal quality through C/No threshold comparison, the system identifies and excludes low-reliability signals before they can contaminate the positioning calculation, thereby preventing rather than just treating noise issues.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If GPS positioning is performed using all available satellite signals, then positioning speed is improved, but positioning accuracy decreases due to inclusion of low-reliability signals

Engineering Contradiction:

Improvepositioning speedVSAvoidpositioning accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies local quality by differentiating between high-reliability and low-reliability GPS satellite signals based on their individual C/No values. Instead of treating all signals uniformly, the system applies different selection criteria to different signals, allowing only those meeting the C/No threshold to be used in positioning calculations, thus optimizing both speed and accuracy.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If C/No threshold is set low to include more satellites, then positioning availability is improved, but positioning accuracy decreases due to noisy signals

Engineering Contradiction:

Improvesatellite selection flexibilityVSAvoidpseudorange accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the C/No threshold parameter based on actual signal conditions. The system compares measured C/No values against the threshold parameter, and this parameter can be adapted to different operational requirements, allowing optimization between availability and accuracy by changing the threshold value rather than using a fixed criterion.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP2618181B1Satellite navigation augmentation system and satellite navigation augmentation method

Publication Date: 2017.01.04 NEC CORP

AI summary

Provided is a satellite based augmentation system comprising: a threshold value calculation unit which calculates a monitoring threshold value for determining whether or not a value of carrier to noise power density ratio (C/No) at a time when a pseudorange is measured on the basis of a signal from a GPS satellite is proper; and a pseudorange determination unit which determines whether or not the pseudorange has proper accuracy by comparing the C/No value and the monitoring threshold value.