Satellite Radio-Navigation Signal Interference Detection

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Solution Overview

Problem

Current satellite radio-navigation signal receivers face delays in detecting narrow-band interference, leading to measurement errors and positioning errors due to the time required to detect aberrant signals.

Innovation Solution

A method that evaluates deformations of the correlation function of the radio-navigation signal by calculating the slope using multiple measurements of the correlation function at different time positions and comparing it to a detection threshold configured based on signal-to-noise ratio, allowing for faster interference detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If traditional aberrant measurement detection methods are used, then detection reliability is maintained, but detection time increases causing delays in identifying interference

Engineering Contradiction:
Improvedetection timeVSAvoiddetection reliability
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The patent applies preliminary action by computing the correlation function and its slope in advance, before interference detection is needed. The slope of the correlation function is calculated as a pre-processing step, allowing rapid comparison against thresholds when interference detection is required, thus reducing detection time while maintaining reliability

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent substitutes traditional mechanical measurement-based detection with a mathematical approach using correlation function analysis. By replacing direct measurement comparison with correlation-based slope analysis, the system achieves faster detection without sacrificing reliability, as the correlation function inherently filters noise and highlights true interference patterns

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If narrow-band interfering signals are present, then signal-to-noise ratio deteriorates, but traditional detection methods fail to detect them quickly enough

Engineering Contradiction:
Improveinterference detection precisionVSAvoiddetection delay
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent changes the detection parameter from direct measurement values to the slope of the correlation function. This parameter transformation makes the detection process sensitive to narrow-band interference patterns while remaining computationally efficient, achieving both high precision and fast detection by analyzing how the correlation function changes rather than absolute values

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The correlation function serves as an intermediary between the raw signal and the detection decision. By introducing this intermediate mathematical representation, the system can detect narrow-band interference with high precision and speed, as the correlation function concentrates interference effects into detectable slope variations while filtering out other signal components

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2869085B1Method for detecting interference in a satellite radio-navigation signal by detecting a deformation of the correlation function
Publication Date: 2017.07.12 THALES SA
  • EP2869085B1 patent drawingFigure 1
  • EP2869085B1 patent drawingFigure 2a~3
  • EP2869085B1 patent drawing

AI summary

A method for detecting interference in a satellite radio navigation signal characterized in that it comprises the following steps: • Calculating (301) information representative of the slope of the correlation function of said signal with a local spreading code, said correlation function having substantially the theoretical shape of an isosceles triangle, said slope being estimated on any one of the sides of equal length of said isosceles triangle, • Comparing (302) said information to a detection threshold configured at least according to a target signal-to-noise ratio