Delta Range Monitoring for GNSS Multiple-Satellite Spoof Detection
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Solution Overview
Problem
Existing GNSS detection methods struggle to effectively detect and mitigate multiple simultaneous erroneous GNSS measurements, particularly in scenarios where lower-grade inertial systems lose coasting capability, leading to potential alignment with spoofed signals.
Innovation Solution
Implementing a delta range monitor in conjunction with a Kalman filter-based system to enhance spoofing detection, disabling GNSS aiding when spoofing is detected, and using the delta range monitor to maintain detection even after the Kalman filter loses capability, with conditions for deactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If solution separation technique is used to detect single satellite errors, then detection capability for single satellite failure is improved, but the system cannot differentiate between multiple satellite failures or single satellite errors that are not large enough to be identified
Solution Approach 1:
The patent segments the detection process into two distinct modules: a delta range monitor for continuous monitoring of range rate measurements, and a solution separation technique for detecting inconsistencies. This segmentation allows each module to specialize in different aspects of spoofing detection, enabling the system to detect both single and multiple satellite failures simultaneously.
Solution Approach 2:
The patent introduces delta range monitoring as an additional dimension of detection beyond traditional solution separation. By monitoring the time derivative of range measurements (range rate), the system gains an extra observational dimension that helps differentiate between multiple satellite failures and single satellite errors with small magnitudes.
2Measurement precision
If GNSS front-end signal monitoring is used to detect spoofed signals, then detection of individual erroneous measurements is improved, but hardware and processing needs increase and the method is not available in downstream systems
Solution Approach 1:
The patent extracts the essential spoofing detection function from the complex GNSS front-end signal monitoring and implements it at the measurement level using delta range monitoring. This extraction allows the system to achieve spoofing detection capability without requiring access to raw GNSS signals or complex front-end processing, making it suitable for downstream commercial INS/GNSS systems.
Solution Approach 2:
Instead of directly monitoring GNSS front-end signals, the patent creates a simplified copy of the detection function using readily available pseudorange and carrier phase rate measurements from commercial GNSS receivers. This copying approach maintains the essential detection capability while avoiding the hardware complexity of front-end monitoring.
3Ease of operation
If commercial INS/GNSS solutions are used, then system availability is improved, but GNSS front-end signal monitoring is not available for spoofing detection
Solution Approach 1:
The patent enables the commercial INS/GNSS system to perform spoofing detection using its own existing measurement outputs (pseudorange and carrier phase rate). The system serves itself by utilizing measurements already produced by the commercial receiver, eliminating the need for external front-end monitoring equipment while maintaining detection capability.
4Ease of manufacture
If lower performing inertial sensors are used, then system cost is reduced, but the duration of spoofing detection effectiveness is reduced when GNSS information is unavailable
Solution Approach 1:
The patent ensures continuous spoofing detection capability by maintaining the delta range monitor independently of the inertial system's coasting capability. The delta range monitor continuously processes GNSS measurements as long as they are available, providing uninterrupted detection effectiveness regardless of the inertial sensor performance or GNSS availability status.
Data Source
AI summary
A system comprises a GNSS receiver in a vehicle that receives satellite signals from GNSS satellites and produces multiple satellite measurements. An INS in the vehicle communicates with the GNSS receiver and includes inertial sensors that produce inertial measurements for the vehicle. A processor, in communication with the GNSS receiver and the INS, hosts a navigation filter and a spoof detector module in communication with the navigation filter. The spoof detector module includes at least a first spoof detection monitor comprising a delta range monitor. The processor is operative to process the satellite measurements and inertial measurements in the navigation filter to produce a navigation solution. The delta range monitor processes the satellite measurements to detect whether there is a spoof event of the satellite signals received by the GNSS receiver. When a spoof event is detected, GNSS aiding of the INS is disabled and the spoof event is announced.