A Non-Traditional Approach to Analysis of Signal Structure Anomalies Observed in PRN 21

摘要

The FAA's WAAS ground stations, distributed across the United States, continually monitor the GPS signals from all SVs for carrier phase anomalies. During 2008, WAAS detected a significantly higher incidence of carrier phase tracking anomalies from SVN45 (PRN21), and to a lesser extent from SVN34 (PRN04), than from the remainder of the constellation. Because the WAAS detected these anomalies simultaneously at multiple geographically diverse ground stations, the anomalies are believed to originate in the satellite. These carrier phase anomalies are a concern because WAAS flags the SV on which they are detected as unusable for several minutes after the event. Understanding these anomalies should provide insight into issues with the GPS satellite signal path, as well as tracking loop behavior in GPS receivers.