Multi-Mode S ADS-B Position Checks for GNSS Spoofing Detection
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Solution Overview
Problem
GNSS systems are susceptible to interference, spoofing, and multi-path signal reception, leading to inaccurate position calculations that can compromise the safety and functionality of aircraft navigation systems.
Innovation Solution
A system that utilizes ADS-B reports from multiple aircraft and active RF measurements to detect GNSS malfunctions and calculate a pseudo-position, which can be used as an independent navigation source when the GNSS position is compromised.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GNSS position is used for navigation, then navigation functionality is provided, but position accuracy deteriorates due to interference and spoofing
Solution Approach 1:
The patent introduces an intermediary system consisting of ADS-B receivers and pseudo-position calculation algorithms that mediate between the compromised GNSS signals and the navigation system. By receiving ADS-B broadcasts from multiple aircraft and calculating pseudo-positions based on relative geometry, the system provides an independent position reference that does not rely on vulnerable GNSS signals, thus resolving the contradiction between maintaining navigation functionality and ensuring position accuracy under interference conditions
Solution Approach 2:
The system implements feedback by continuously monitoring GNSS position against independently calculated pseudo-positions and providing integrity alerts when discrepancies indicate spoofing or interference. This feedback mechanism allows the navigation system to detect and respond to degraded GNSS reliability, switching to or augmenting with the pseudo-position source when needed, thereby maintaining both navigation functionality and position accuracy
2Reliability
If independent position source is created using ADS-B reports, then position reliability improves, but system complexity increases
Solution Approach 1:
The patent leverages the universality of existing ADS-B infrastructure by using broadcast position reports from multiple aircraft that are already transmitting this information for other purposes. The same ADS-B receivers used for traffic awareness and collision avoidance are also utilized for pseudo-position calculation, allowing the system to gain independent position verification capability without adding dedicated hardware, thus improving position reliability while minimizing the increase in system complexity
Solution Approach 2:
The system performs self-service by using the collective ADS-B reports from surrounding aircraft to generate the pseudo-position information needed for its own navigation integrity. Rather than requiring external ground-based reference systems or additional dedicated positioning infrastructure, the aircraft self-generates its independent position reference from the broadcast data of other aircraft in the vicinity, reducing system complexity while maintaining reliability
Data Source
AI summary
Determine a GNSS based position malfunction and further estimate an own-ship position when determining that the GNSS position may be inaccurate. The system of this disclosure may use information either from any one or more of internal navigation systems and external information sources to determine whether a GNSS based position for the own-ship may be inaccurate and to provide a pseudo position for the own-ship as an independent position source. The system of this disclosure may determine the existence of the GNSS malfunction based on independent position information.