Satellite Navigation Spoofing Detection via Phase Difference Analysis
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Solution Overview
Problem
Current satellite navigation systems are vulnerable to spoofing attacks, where fake navigation signals can be superimposed on real signals, making it difficult to distinguish between them, and existing countermeasures are either ineffective or technically complex.
Innovation Solution
A device and method using at least two antennas to determine phase differences in received signals, allowing for the detection of fake signals without requiring directional antennas or complex alignment, by recognizing almost identical phase differences as indicative of signals originating from a single source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If directional antennas or multiple antennas of known geometry are used to detect signal direction, then spoofing signals can be detected, but the receiver requires complex alignment and the system becomes more complex
Solution Approach 1:
The invention changes the parameter being measured from signal direction (requiring antenna alignment) to phase difference (which is inherently available in signal processing). By measuring phase differences between signals received at different antennas and comparing them across multiple satellite pairs, the system can detect spoofing without requiring complex antenna alignment procedures.
Solution Approach 2:
The invention introduces phase difference as an intermediary parameter that mediates between the physical antenna setup and the detection goal. Instead of directly measuring signal direction (which requires aligned antennas), the system measures phase differences (which are easily obtained) and uses these as an intermediary to infer spoofing conditions through comparison across multiple satellite pairs.
2Reliability
If RAIM techniques are used to detect forged signals, then some forged signals can be detected, but complete constellation spoofing cannot be detected
Solution Approach 1:
The invention segments the detection approach by analyzing multiple independent satellite pairs separately. Each pair provides an independent phase difference comparison, allowing the system to detect spoofing even when some satellites are compromised. This segmentation enables detection of complete constellation spoofing by showing inconsistent phase relationships across different satellite pairs.
Solution Approach 2:
The invention uses excessive action by measuring phase differences for multiple satellite pairs beyond the minimum required for basic navigation. This excess measurement provides redundant information that enables detection of sophisticated spoofing attacks affecting entire constellations, going beyond what standard RAIM can detect.
3Reliability
If signal strength observation is used to identify deceivers, then spoofing signals can be detected, but the method is not reliable due to signal strength fluctuation
Solution Approach 1:
The invention substitutes the mechanical/physical measurement of signal strength (which is prone to environmental fluctuations) with a phase-based measurement approach. Phase differences can be measured with high precision through signal processing and are not affected by the same environmental factors that cause signal strength variations, providing a more reliable spoofing detection metric.
4Reliability
If authentication of navigation message is used, then message integrity can be verified, but manipulated signals with real messages cannot be detected
Solution Approach 1:
The invention performs preliminary action by measuring and recording phase differences for multiple satellite pairs before attempting to detect spoofing. These preliminary phase difference measurements serve as a reference that can be compared against expected geometric relationships, enabling detection of manipulated signals even when they contain authentic-looking navigation messages.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables reliable detection of spoofing transmitters emitting incorrect navigation signals, preventing their impact on position determination, especially in safety-critical applications like air navigation, using commercially available antennas and receivers.
Implementation Method 1
determining phase differences of the received signals for each antenna
Data Source
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Figure 2
AI summary
The device has two omnidirectional antennas (12, 14) comprising receivers for receiving navigation signals (240, 260, 280, 300), and a phase difference measuring unit (16) to determine phase differences of the received navigation signals for each antenna based on carrier phase measurements. A detection unit (18) detects falsified navigation signals (320, 340) among the received navigation signals using the determined phase differences. A reference wave unit (20) generates a reference wave with a same frequency as a carrier wave of the received navigation signals. Independent claims are also included for the following: (1) a system that uses signals of a satellite navigation system (2) a method for detecting falsified signals in a satellite navigation system.