Periodic Frequency Variation for Spoofing-Resistant Time Transfer
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Solution Overview
Problem
Current radio navigation satellite systems (RNSS) face security concerns due to unencrypted signals, which can be spoofed, leading to unauthorized manipulation of receivers, especially in military applications, where traditional encryption methods are resource-intensive to protect.
Innovation Solution
Periodically varying the center frequency of signals broadcast by RNSS satellites with a predetermined MHz and corresponding time period, allowing receivers to form a trustworthy timing solution by mapping combinations of center frequencies to specific times, providing an independent verification of signal authenticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If unencrypted signals are used for RNSS broadcasting, then ease of operation and signal accessibility are improved, but security and resistance to spoofing deteriorate
Solution Approach 1:
The patent applies periodic action by varying the center frequency of RNSS signals in a periodic manner. The frequency shifts between two values (f1 and f2) over time periods T1 and T2 respectively, creating a time-varying frequency pattern that is easy to implement but provides security against spoofing. This periodic frequency variation allows legitimate receivers to verify signal authenticity while maintaining unencrypted signal accessibility.
2Reliability
If encrypted signals are used for protected position service, then security is improved, but device complexity and processing requirements worsen
Solution Approach 1:
The patent applies parameter changes by modifying the frequency parameter of the RNSS signal instead of using encryption. The center frequency is shifted between two values (f1 and f2) in a periodic manner, creating a physical layer security mechanism. This approach provides security through parameter variation rather than cryptographic encryption, reducing device complexity and processing requirements while maintaining security against spoofing.
3Reliability
If frequency variation is implemented for signal authentication, then spoofing resistance is improved, but signal processing complexity worsens
Solution Approach 1:
The patent implements periodic frequency variation where the center frequency alternates between f1 and f2 over time periods T1 and T2. This periodic pattern creates a predictable yet secure signal structure that provides spoofing resistance. Receivers can track the frequency variations using standard phase-locked loop (PLL) techniques, keeping the processing complexity manageable while achieving reliable spoofing detection through timing and frequency correlation.
Data Source
AI summary
A system and method for periodically varying a center frequency for assured time transfer in order to securely transfer a signal from a source to a receiver, without adding additional encryption to signal.