GNSS Spoofing Detection via SBAS Orbital Distance Comparison
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Solution Overview
Problem
GNSS receivers are susceptible to satellite signal spoofing, which can lead to incorrect position outputs, posing hazards to avionics safety, especially during aircraft flight and landing approaches.
Innovation Solution
A method and system for detecting satellite signal spoofing by monitoring satellite signals from GNSS and SBAS satellites, computing satellite orbital positions, determining distance values, and comparing them to detect anomalies that indicate spoofing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GNSS receiver uses standard 24 channel design, then receiver complexity is limited, but susceptibility to spoofing threats increases
Solution Approach 1:
The patent introduces an intermediary verification mechanism that compares independently calculated satellite positions (from ephemeris data) with reported satellite positions (from navigation messages). This intermediary comparison layer detects spoofing without fundamentally redesigning the GNSS receiver architecture, adding spoofing resistance while maintaining reasonable complexity.
Solution Approach 2:
The system performs preliminary verification of satellite signal authenticity by calculating expected satellite positions before using the navigation data. By pre-computing satellite ephemeris and comparing it with received signals, the system detects spoofing attempts in advance, preventing erroneous position outputs before they affect aircraft systems.
2Measurement precision
If GNSS receiver processes multiple satellite signals, then positioning accuracy improves, but detection of spoofing anomalies becomes more difficult
Solution Approach 1:
The patent implements a feedback mechanism where the receiver continuously monitors the consistency between independently calculated satellite positions and reported positions. When discrepancies exceed a threshold, the system generates spoofing alerts. This feedback loop enables detection of spoofing anomalies while maintaining accurate positioning from multiple legitimate satellites.
Solution Approach 2:
The verification process applies local quality checking to individual satellite signals by comparing each satellite's reported position with its independently calculated position. This localized verification approach maintains overall positioning accuracy from multiple satellites while detecting spoofing anomalies in specific signals without requiring complete system redesign.
3Reliability
If GNSS receiver relies on satellite signals for position output, then navigation performance is maintained, but vulnerability to spoofing threats increases
Solution Approach 1:
The system applies preliminary anti-action by pre-calculating expected satellite positions using ephemeris data before processing navigation messages. This pre-computed reference framework actively counteracts spoofing threats by providing a baseline for detecting fraudulent signals, thereby protecting navigation safety without compromising the ability to use satellite signals for positioning.
Solution Approach 2:
By performing preliminary verification of signal authenticity through independent position calculations, the system prepares a trusted reference framework before relying on satellite signals for navigation. This preliminary action ensures navigation safety by detecting spoofing attempts before they can compromise the position output used by aircraft systems.
Data Source
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AI summary
A method for detecting spoofing comprises monitoring signals from GNSS and SBAS satellites with a GNSS receiver; obtaining current time and orbital parameters from the receiver, based on real-time signals from the satellites; computing orbital positions based on the current time and orbital parameters; retrieving past orbital parameters; calculating predicted orbital positions based on the orbital parameters with respect to current time and the past orbital parameters; computing current orbital positions based on current satellite signals; determining a first distance value between two or more of the satellites based on the predicted orbital positions; determining a second distance value between two or more of the satellites based on the current orbital positions; comparing the first and second distance values to obtain a discriminator value; determining whether the discriminator value is greater than a threshold level, and outputting a spoofing alert when the discriminator value is greater than the threshold level.