Terrestrial Beacon Time Broadcasting With Integrity Monitoring
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Solution Overview
Problem
Existing methods fail to provide a precise and integrity-guaranteed time service using terrestrial beacons, especially in the presence of accidental failures or malicious acts, and lack integrity control adapted to time transfer systems.
Innovation Solution
A method for broadcasting time and measuring integrity using a network of synchronized terrestrial beacons, involving pseudo-distance measurements, a maximum likelihood criterion, and a resolution algorithm to detect clock or position biases, with a protection zone defined for time offset integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If terrestrial beacons are used for time broadcasting, then time synchronization can be achieved without GNSS or wired channels, but the system becomes vulnerable to accidental failures and malicious acts affecting beacon integrity
Solution Approach 1:
The patent implements integrity monitoring that continuously checks beacon signals and provides feedback to detect failures or malicious acts. The system monitors the consistency of time information from multiple beacons and alerts when discrepancies indicate potential integrity issues, enabling continuous verification of time service reliability.
Solution Approach 2:
The patent introduces an intermediary integrity monitoring layer between the beacons and the time synchronization process. This intermediary component analyzes beacon signals for consistency and validity before accepting them for time synchronization, preventing compromised beacon data from affecting the overall time service integrity.
2Measurement precision
If multiple beacons are monitored for integrity, then detection accuracy improves, but the computational complexity and processing time increase
Solution Approach 1:
The patent segments the integrity monitoring process into distinct modular components: signal reception, consistency checking, failure detection, and alert generation. Each module handles a specific aspect of integrity monitoring, making the overall complex system manageable and maintainable while improving detection accuracy through specialized processing at each stage.
Solution Approach 2:
The patent implements monitoring of multiple beacons beyond the minimum required for time synchronization. By excessively monitoring more beacons than strictly necessary, the system achieves higher integrity detection accuracy through increased redundancy and cross-verification opportunities, while the modular structure keeps processing complexity manageable.
3Reliability
If real-time integrity monitoring is implemented, then immediate detection of failures is achieved, but the processing load and system resource consumption increase
Solution Approach 1:
The patent implements periodic integrity monitoring at strategically chosen intervals rather than continuous monitoring. The system checks beacon integrity at regular intervals sufficient to detect failures and malicious acts while allowing processing resources to rest between checks, significantly reducing energy consumption while maintaining reliable failure detection capability.
Solution Approach 2:
The integrity monitoring system uses the existing beacon signals and receiver processing capabilities to perform self-verification without requiring additional dedicated hardware or excessive external resources. The system leverages its own operational data for integrity checks, minimizing additional energy consumption while maintaining robust failure detection.
Data Source
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AI summary
The invention relates to a method for time broadcasting and integrity measurement for a radio frequency receiver linked to at least four synchronized terrestrial time transfer beacons, comprising the steps of: - determining (301) a pseudo-distance for each beacon, - solving (302) an algorithm optimizing a maximum likelihood criterion that resolves the positions of the beacons, the receiver, and the receiver's time offset, - calculating (303) a test variable T and an associated alert threshold (304), and raising an alert when the threshold is exceeded, and otherwise - determining (305) a non-centrality parameter λ of the test variable T, and a minimum detectable clock bias (306) and position bias (307) for each beacon, - determining (308) a time protection zone and comparing it with an alert zone. Radiocommunication equipment implementing the method and associated computer program.