Identifying Low Cost GNSS Monitor Metrics for Robust RFI Detection

Global Navigation Satellite Systems (GNSS) are a vital tool to the world, but, they are susceptible to intentional and unintentional radio frequency interference (RFI). This paper focuses on developing robust metrics for a low-cost GNSS RFI monitor for interference detection and classification. The research evaluates the response of different metrics commonly found in GNSS receivers in laboratory experiments and under real open sky conditions. The metrics evaluated are the Automatic Gain Control (AGC), available satellites and carrier-to-noise ratio (C/N0). Open sky experiments allow for the metrics to be characterized under long duration datasets and diverse satellites geometries, revealing their limitations. To make such metrics robust, different filtering techniques are applied alongside the creating of new metrics. These techniques and the combination of metrics can allow for strong and weak RFI events to be detected in a reliable way.