Spurious Signal Detection in GNSS Receivers via Known-Bit Correlation
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Solution Overview
Problem
GNSS receivers face performance degradation due to spurious signals that are misidentified as valid space vehicle transmissions, leading to detector errors such as false alarms and misdetections.
Innovation Solution
A method and system for detecting spurious signals in GNSS receivers by determining known-bit data sequences of valid space vehicle signals, generating correlation statistics based on these sequences, and verifying whether the signals are spurious by comparing the correlation statistics to a threshold value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If conventional detection techniques are used to identify spurious signals, then detection capability is improved, but detector errors (false alarms and misdetections) increase
Solution Approach 1:
The patent introduces an intermediary verification process that uses known-bit patterns as a mediator between the initial signal detection and the final validation. The detector first identifies potential spurious signals using conventional techniques, then uses the known-bit pattern verification as an intermediate step to confirm whether the detected signal is actually spurious or a valid SV signal, thereby reducing false alarms and misdetections
Solution Approach 2:
The system implements feedback by using the correlation statistic results from known-bit pattern matching to adjust and refine the spurious signal detection process. The verification outcome feeds back into the detection system to improve future detections, reducing detector errors through iterative refinement based on the reliability sequences and correlation statistics
2Reliability
If known-bit pattern verification is implemented, then false alarm rate is reduced, but device complexity increases
Solution Approach 1:
The detector circuit is segmented into distinct functional blocks: a known-bit pattern generator that creates verification sequences, a correlation statistic calculator that compares received signals against known patterns, and a decision logic unit that uses reliability sequences to make final determinations. This segmentation allows the complex verification process to be implemented through modular, manageable components
Solution Approach 2:
The known-bit pattern verification mechanism serves multiple functions simultaneously: it verifies signal authenticity, calculates correlation statistics for detection, generates reliability sequences for decision-making, and provides feedback for continuous improvement. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby managing overall device complexity
Data Source
AI summary
A system and a method are disclosed for detecting a spurious signal in a Global Navigation Satellite System (GNSS) receiver. A detector of the GNSS receiver determines a first sequence of known bits or known-bit transitions of a space vehicle (SV) signal of a target SV. A second sequence is determined based on a coherent sum of the SV signal being tracked by the GNSS receiver. A first reliability sequence may be associated with the first sequence, and a second reliability sequence that may be associated with the second sequence. A correlation statistic of the first sequence is determined based on the second sequence. Whether the first SV signal is a spurious signal is determined based on a comparison of the correlation statistic to a threshold value.