GNSS Jamming Detection and Exclusion for Trustworthy Virtual Balise Capture in Satellite-Based Train Control

Jamming to satellite navigation signals has become a major threat to the safety critical train control systems using Global Navigation Satellite System (GNSS), where the Virtual Balise (VB) concept enables a specification-compatible solution to utilize GNSS and reduce the physical Balises. This paper presents a novel GNSS jamming detection and exclusion solution to achieve trustworthy capture of VBs. An advanced architecture of Virtual Balise Reader (VBR) is proposed by integrating an Interference Qualifier Module (IQM) into the conventional GNSS-enabled VB framework. To enhance the trustworthiness of the VB capture, the IQM detects and identifies the existence of interference by examining the residuals between the real and predicted GNSS pseudo-ranges, which are generated by the odometry data and the trackmap. A discrimination test approach is utilized to evaluate the availability of raw satellite measurements according to the statistical analysis. We embed the performance indicator for each pseudo-range into the VB capture logic to isolate the degraded measurements and, meantime, adopt an adaptive Capture Interval Limit (CIL) to avoid the unexpected missed capture. Data sets from a GNSS jamming injection-based test platform are used for comparative studies, demonstrating the necessity and superiority of the proposed solution in improving the interference protection capability and trustworthiness of VB capture under the GNSS jamming environment.