GNSS Receiver Synchronization for Spoofing Direction Localization
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Solution Overview
Problem
Mass-market GNSS receivers are incoherent due to differing clocks and local oscillators, preventing accurate detection and localization of spoofing attacks.
Innovation Solution
A system comprising two or more receivers, antennas, and a spoofing detection computing device that calibrates receivers with a simulated reference signal to compensate for phase offsets, computes DOA, and uses satellite ephemeris data to detect and localize spoofing signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mass-market GNSS receivers are used to reduce cost, then device cost decreases, but phase coherence between receivers deteriorates due to different clocks and local oscillators
Solution Approach 1:
The system performs preliminary calibration by transmitting a reference signal from a known location before DOA estimation. This preliminary action compensates for phase offsets between incoherent receivers, enabling subsequent accurate spoofing detection without requiring expensive coherent hardware
Solution Approach 2:
A reference signal transmitted from a known location serves as an intermediary to establish phase relationships between incoherent receivers. This intermediary signal allows the system to calculate and compensate for phase offsets, bridging the coherence gap between cheap mass-market receivers
2Reliability
If coherent GNSS receivers with shared clocks are used to maintain phase alignment, then phase coherence improves, but device complexity and cost increase
Solution Approach 1:
Instead of requiring expensive coherent hardware with shared clocks, the system creates a virtual coherent reference by transmitting a known reference signal from a controlled source. This copying approach allows mass-market receivers to behave as if they were coherent, achieving the same effect without the complex hardware infrastructure
Solution Approach 2:
The patent replaces the mechanical/hardware solution of shared clocks and synchronized oscillators with a software/signal-processing solution. By using reference signal-based calibration and phase offset compensation algorithms, the system achieves coherence without the complex physical synchronization infrastructure
3Device complexity
If phase differencing is performed without calibration to simplify processing, then processing complexity decreases, but measurement precision deteriorates due to uncorrected phase offsets
Solution Approach 1:
The system performs preliminary calibration using a reference signal from a known location before conducting DOA estimation. This advance compensation for phase offsets ensures that subsequent measurements are accurate, allowing the use of simple phase differencing algorithms without sacrificing precision
Data Source
AI summary
A system, non-transitory computer-readable medium, and method include one or more clusters where each of the clusters includes two or more receivers coupled to one of two or more antennas and a computing device coupled to the two or more receivers. The computing device comprises a memory coupled to a processor which is configured to execute programmed instructions stored in the memory to: calibrate the receivers with respect to a simulated signal to compensate for any initial phase offset; compute with the calibrated receivers an estimated direction of arrival of each received geo-reference signal from the receivers each coupled to the one of the antennas; determine when any of the received geo-reference signals is a spoofing signal based on the computed estimated direction of arrival and satellite ephemeris data; execute a localization algorithm on the spoofing signal to calculate a spoofing source location; and output the spoofing location.